Moparts

Super duper MPG 273/318 experiment ! NUMBERS!!!!!!!

Posted By: HotRodDave

Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 11/11/07 12:46 AM

I have a 273 sitting out back seasoning and thought it would be fun to build it to get the best possible gas miledge and slide it in the 68 cuda for a while. Heres what I was thinking,

.060 over bore
cheap light weight I beam rods.
Cast crank, turned down to balance it.
Custom light weight pistons Zero decked
Coated on top and skirts
Stock Magnum heads
318 2bbl cam or shorter duration if some one knows one, mabey even custom.
Windage tray.
800 cfm Thermo-quad
Offy dual port intake
Screens over intake ports
195 t-stat
2.76 gears
A-500 trans

I think the heads will fit with no bore notches if I turn the valves to 1.88 diameter(the seat on these heads are way in from the edge of the valve) The one side will be shrouded but that should help swirl everything up.

The cam needs to be the shortest duration I can find to build tons of vaccume. And also the mag rockers 1.6 ratio will help the lift a hair to help it make a little bit of power any how.

I have TTI headers for the car any how so that should help.

Any one has any suggestions feel free to throw in your

It currently has a 318 low comp open chamber headed 2bbl and gets 22mpg high way and 18 intown. The goal would be ultimate miledge and any HP it can make without sacrificeing MPG would just be a nice bonus.

One more thing, I may bump the comp up a bunch and run it on e-85. Havent decided on that one yet, the other choice would be pump 93 octane.
Posted By: CudaMike

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 02:46 AM

Dave, I'm thinking the Magnum heads may be a little big for a 273, since it is about 85% the size of a 318 (the smaller of the two Magnum headed engines). I'm thinking 302's with a good valve job and a little touchup blending. But, you would be giving up the 1.6 rockers. A custom cam could make up for that.
With the O.D. trans the 2.76's may be a little too tall, but maybe not.
Just thinking out loud
Posted By: mopowergtx

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 02:47 AM

The E-85 would be going the wrong way to try and get better fuel mileage right? From what I read thats the way I understand it. Higher octane but lower mileage. Would a later model roller cam 318 be a better start evan though its got the extra cubic inch to feed? Thinking this because I wonder does the roller cam's reduced friction offer anything in the way of mileage benifit? I take it cast cranks are lighter than the stock forged 273 unit? Run the 273 full floater rods they should be lighter than the later model versions I believe. If you need a good stock set you can have the stock rods from my 67 318. What about 2.4 rear gears like in the late model 8 1/4. Man with an overdrive you could get that thing to idle at highway speeds. I know the KB Hyper pistons are almost 100 grams lighter than a stock piston so you'll shake some weight there too. Can you get a stock air cleaner for a 4 barrel Cordoba maybe and use the fresh air pipe and route it somehow on the Cuda to grap cool outside air for it? If you ran an old Edlebrock performer intake don't they have the correct choke well for a Thermoquad? Does reducing oil windage offer any mileage? Just some more thoughts. Sounds like a cool experiment.
Posted By: mopowergtx

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 02:51 AM

Oh would running a twin electric fan setup with no engine fan make a difference?
Posted By: 68Cbarge

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 02:52 AM

Quote:

Dave, I'm thinking the Magnum heads may be a little big for a 273, since it is about 85% the size of a 318 (the smaller of the two Magnum headed engines). I'm thinking 302's with a good valve job and a little touchup blending. But, you would be giving up the 1.6 rockers. A custom cam could make up for that.
With the O.D. trans the 2.76's may be a little too tall, but maybe not.
Just thinking out loud



Yep.2.76's will be too tall with the O/D.
3.23's will be better.
Ditto on the 302 heads.
How about using a stock 360 2bbl grind cam? Just a thought.
Posted By: JDMopar

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 02:56 AM

If you run an A500 OD with 2.76 gears,you're gonna have to drive about 95-100 mph to keep the motor in the sweet spot! 3.23 gears are about the bottom of the barrel to run with an OD tranny. I plan on trying an A999 lockup tranny with 2.45 rear gears in my wifes 69 Dart conv. The A999 will have the low first gear.I'd be interested to read what some of the good engine builders here have to say about what to do to a 273 to make it get good gas mileage.
Posted By: DaytonaTurbo

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 02:59 AM

Play with this

http://vexer.com/68rt/speed.html

You'll see an o/d with 2.x gears is just too low. You don't want to be under 2000rpm at 60 IMO. Too low of an rpm, even on a tiny cammed engine can drop it below it's power band too far and cost you fuel mileage. IIRC, for cruise rpm, ideally you want to be 100-200 rpm below your torq peak for best mileage.

What about a wideband o2 so you can actually tune the thing to get a nice lean a/f ratio? And a exhaust gas temp gauge to tune your ignition timing to optimal? Yeah where do you stop, lol.

I wonder if a roller teen would be better for mileage. A roller is easier to spin over so I could see it helping. However I did change to a roller in my 87 daytona and noticed no difference in mileage at all, although the roller was more aggressive of a grind than the stock cam.
Posted By: mopowergtx

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 03:28 AM

Quote:

You'll see an o/d with 2.x gears is just too low. You don't want to be under 2000rpm at 60 IMO.



Not knocking your opion of what you want for rpm versus mph but my stock 360 '01 1500 Ram 4x4 3.55 rear gear and stock 16" rims and tires with overdrive runs under 2000 rpm at 60 mph.
I get 15.5 mpg combo city/highway with it. Its been awhile since I drove my stock 77 Cordoba 400 thermoquad with 2.4 rear gears and it doesnt do much better than 2k at 60 as I remember. My thinking is if your cam(small) and engine combo makes good power starting at 1000rpm well what would hurt cruising at 1700-1800k in OD? Figuring the cam he'd probably run would be peaked at around 4000 to 4500 rpm. It doesnt take much power to maintain highway speeds. Correct me if I'm wrong I believe Chrysler evan offered a 2.2 gear set in 7 1/4 or 8 1/4. I think it was in the Diplomat body.
I think its all relitive to your setup.
Posted By: da50r

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 06:22 AM

You know what is funny... my wife and I took out 67 Dart 273, 2 bbl on a trip. We got 26 MPG real highway miles per the GPS which I think is accurate. Is that not amazing? I love that car.
Posted By: DaytonaTurbo

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 07:50 AM

Yes, however your ram has a lockup converter, as did the later 318 powered cars. Take a stock 60's 3sp trans, stick a 2.2 rear gear into it and at cruise speed on the highway your rpms will be so low that the converter is slipping.
Posted By: feets

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 02:32 PM

After calculating the proper gearing, the next step will be driving habits.
After that, aerodynamic aids along with tire pressures and alignment will be key.
It's all in rolling resistance.
Posted By: RodStRace

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 04:18 PM

I agree with the stuff posted. keyboard build the engine to make torque at 1800-3000, then set up the drivetrain to roll in that range.
I don't know if the magnum heads will work on those small bores.
a roller cam would allow you to keep the dynamic compression up, along with velocity. You will have to juggle that with mech. compression to keep it from pinging. I'd question the 60 over for that reason.
Low weights, good tolerances, high velocity, and max squeeze are the basic steps. I wonder if going with a smaller exhaust would help tune this combo (build torque down low)?
Posted By: TC@HP2

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 04:42 PM

To get the engine working efficiently and loaded up on torque, you need as much cylinder pressure as possible. This means small duration cam to keep the sweet spot low and as much compression as your local gas supply will allow.

Yes, going to E-85 will cost you in mileage as it takes 30% more alcohol to make the same power as gasoline, so your burning more of it. But, total cost involved may also be a factor. In my flex fuel vehicle, 04 Suburban, it is a wash cost wise when gas is $2.95 and E-85 is $2.35. If the price spread gets greater than that, then E-85 becomes more economical from a financial stand point. Below that price point gas is better.

I also agree that you don't want to spin the engine to low. To cruise down the highway only takes 50-60 horsepower. So you want to have the maximum amount of torque at the smallest possible throttle opening regardless of rpm, within reason. This will be much more efficient than spinning the engine slower just to keep the rpm down.

Everything that applies to performance engine building applies to mileage engine building. It is just that the return is greatly diminished. Sure, roller cams may provide less friction across the rpm range and at peak power are worth an extra 12 lb ft and 10 hp. That same set up in a mileage build may still have reduced friction and increased power, but only have an extra 2 lb ft and 2 hp. Also, total cost involved is a determinate of what you want to do. You could easily spend $20k building a trick motor that will only get 3-5 more mpg that a good solid blueprinted and balanced build up that costs $7-8 grand.

For the car, you want to lighten it as much as possible. An A body is already kind of small, so you punching a much smaller hole in the air than a E body. Not much you can do for aero as a dart is a brick no matter how you look at it. Skinny high pressure tires, synthetic grease and fluids to reduce resistance, a whole bunch of little tricks can gain you a lot.
Posted By: Supercuda

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 05:33 PM

The least aerodynamic part of a car is the stuff under it.

A belly pan woud be a fairly cheap and effective addition. Just remember to allow for air to flow out of the engine compartment, the radiator will thank you.

Back when I had my Diplomat 318 powered I could turn mid 20's on the highway. That was with 2.24 gears and an aerodynamic package at least as brick like as yours. City mileage was horrible though, even with the low first gear trans adn a lock up converter.

I later put in a 360, an A833 and a set of 2.94 gears and would turn low 20's with that combo. City mileage wasn't too bad then.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 08:42 PM

The reason I would mabey use the E-85 is I can bump compression up a bunch and with increased compression comes increased efficency and it should offset a bunch of the differance. Flex fuel vehicles will always suck a bunch more ethenol than gas.

I have driven the 80s cars with 2.20 gears and they were fast enough for this experiment and my engine should be more efficent at low rpms with a good tight quench and small bore. I have an 8.75 rear with 2.76 gears and going 80 mph it could already stand another gear shift. I can find no higher gear for the 8.75. Lots of newer cars are under 2000 at 60 even 70. The A-500 has the low gears in it and I want one in there any how.

I was thinking of the offy dual port intake because the small primary runners should really keep velocity up at the low rpm cruise range. I don't have one of these yet though. I do have a street dominator, and LD4B and a factory single plane 2bbl.

The 302 head would be a good idea, any one want to throw a set my way? I'll trade for a set of cracked mags!

I was thinking the mags also because I had them. I have seen 1.88s on a .030 bore 273 and they were almost touching the bore, that is why I was thinking .060 over.

I have a cast crank and they are lighter, thats why I thought I'd use it.

The only rods I have are factory magnums, hence the thought of useing chinese I beams.

I don't have a spare 318 block sitting around but people should be able to use one for a clone with similar results.

I think the tq peak of 273 and 318 2bbls were both around 2000. I would be attempting to bring it down a hair from there.

I think HP will be livable I am not woried about that, the HP will take care of itself. I don't expect it to be a fast ride with this motor.

A belly pan is a good idea, I think I can figure that out.

I recently put an electric fan on the car but have not checked miledge since. It really suprised me how little I have to run it to keep the current motor cool.

Keep the sugestions comeing you guys are throwing out some good ideas.
Posted By: mopowergtx

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 10:51 PM


Quote:

Yes, however your ram has a lockup converter, as did the later 318 powered cars. Take a stock 60's 3sp trans, stick a 2.2 rear gear into it and at cruise speed on the highway your rpms will be so low that the converter is slipping.



He said he was going to use a
Quote:

A-500 trans


Thats a lock up torque converter trans same as my Ram. Dave I messed around with my Ram today watching the tach and my speed in OD with a load of firewood in the back. 10-15% uphill grade at 1800 rpm in OD at around 57 mph and it was fine. Wasn't losing any speed. Was pulling fine. I like the consesus here that you need to put it between 1800-2000 at your normal cruising speed. Dave if you could get your hands on a 7 1/4 or 8 1/4 that would bolt in it that would be instant mpg bonus versus the heavier 8 3/4. Lightweight aluminium wheels sounds like a good idea too. What year did the Dippys and 5th Aves get roller cam motors? Theres a 86 I believe here next to my house I been thinking about getting for the K-member on the cheap. I need to come down to Tenn anyhow and see Defeo, guy owes me twenty bucks!
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 11:52 PM

I would have a final drive ratio of 1.904 and it is not much more than a 2.20 for steady speed cruising and I would have a better take off gear. With a 27 inch tire it would do 2000 right at 80 mph. I am planning to move out west with even higher speed limits so I think this should work out fine.

Just for fun I figured a 2.20 and OD would make a 1.52 final drive ratio and put 2000 right at 100 mph

I agree the roller cam would probably get a couple more hp because of friction loss but a flat tappet can get more lift at those real short duration numbers. I think with the magnums 1.6 or mabey even some 1.7 rockers and a custom short duration cam I could still open the valves a good amount to get some more tq.
Posted By: rbstroker

Re: Super duper gas miledge 273 experiment !!! - 11/11/07 11:58 PM

da50r, what trans, gear, and tire size are you running. I am putting a '65 273 Dart together hoping for some good mileage and a prostreet look. My Coronet stroker is fun until it comes time to fill it up which is pretty often.
Posted By: RichV

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 01:58 AM

Fuel Inject it. That way you can use lean cruise.


Another idea, turn it into a Aktinson cycle engine (not the diet craze). You do this my using a high mechanical compression ratio around 12 to 1 then have the intake valve held open until after BDC so some of the intake gases are bled off. This will result in higher mechanical efficiency, but low power. Aktinson cycle engine are very popular in hybrid applications.
Posted By: Prince_Valiant

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 02:33 AM

For an auto, I'd probably run 3.21's in a 8 1/4 or 3.23's in a 7 1/4 rear.

Look to getting the lightest parts possible.

I ran a 360, fresh but mild build, with 2.94 gears and the OD 4speed manual...did GREAT with mileage (best trip, 55mph was 26mpg...tended to average high teens and low 20's). The large torquey engine did fine with the super tall gearing, wide ratio's. This was in an A-bod, with an 8 1/4 rear. Stock compression, MP .450 cam, performer intake, holley 600, hedman headers, MP ignition in a 76 valiant 4 door.
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 02:32 PM

if you're looking more for economy than power, I'd look for a 7.25 or 8.25 axle. less mass, which is a good thing. also, I'd probably look at 2.94-3.23 gears with the OD. I'd also look at an A833OD instead of the A500 (less mass, and planetary geartrains are not as efficient as regular bevel geartrains)

another option for highway efficiency would be a slant 6 A833 (3.09 first gear, 1:1 4th) with like a 5th ave/diplomat 2.2-2.45 rear gear. technically, the least amount of geartrain loss in a manual tranny is in direct drive), and the 3.09 first will make take off tolerable.

personally, I'd go a 318 roller as a base, either using the 302's that came on it, or the mag heads. I'd use a hughes HER9204AL (192/204@.050, 114LSA, .459/.471" lift with 1.5's and .490/.502" lift with 1.6's--that's some pretty fast ramps)for the cam, and KB167's (or equivalent KB forged) for pistons. frankly, I don't think rod weight would come into play that much, I'd probably use the magnum stockers. that should be right about 10:1, I'd go super tight on quench, probably ~.035"....I bet it would still run on pump premium, you might have to play with where you install the cam, or timing. thermal barrier coat the tops of the pistons and the combustion chambers, and pump gas should be fine.

couple that with a standard eddie performer intake (as they seem to make the most torque down low of the small block 4bb intakes, at the expense of upper RPM power), headers and a small t-quad. or if you use the mag heads, I'd use a stock mag intake, smooth out the throttle body, and run the whole thing with a megasquirt, or GM TPI computer....you can get way more creative on fueling and timing curves with EFI to max out economy.
Posted By: Rug_Trucker

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 02:47 PM

Dave, I have a stocker 360 cam, and I have a Melling Blue Racer Wolverine RV cam. It is a .414 single pattern cam. Take you pick. I put 9K on it then switched engines and bought a Comp .425 lift RV cam.

I also have a SP2P Eddie intake. It is the TQ mount one.

You can have either cam for free.

The Eddie might be better than the Offy (Offy on my van engine) I might want some money for that or maybe trade for something.

I am thinking the SD is over kill and will kill the torque.
Posted By: Qbird

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 04:04 PM

Quote:


Quote:

Yes, however your ram has a lockup converter, as did the later 318 powered cars. Take a stock 60's 3sp trans, stick a 2.2 rear gear into it and at cruise speed on the highway your rpms will be so low that the converter is slipping.



He said he was going to use a
Quote:

A-500 trans


Thats a lock up torque converter trans same as my Ram. Dave I messed around with my Ram today watching the tach and my speed in OD with a load of firewood in the back. 10-15% uphill grade at 1800 rpm in OD at around 57 mph and it was fine. Wasn't losing any speed. Was pulling fine. I like the consesus here that you need to put it between 1800-2000 at your normal cruising speed. Dave if you could get your hands on a 7 1/4 or 8 1/4 that would bolt in it that would be instant mpg bonus versus the heavier 8 3/4. Lightweight aluminium wheels sounds like a good idea too. What year did the Dippys and 5th Aves get roller cam motors? Theres a 86 I believe here next to my house I been thinking about getting for the K-member on the cheap. I need to come down to Tenn anyhow and see Defeo, guy owes me twenty bucks! [/quot


20 Bucks!!!...how do I owe you 20 bucks?....
Posted By: Rug_Trucker

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 04:16 PM

Did you lose a bet Tony? He may spend more in gas to collect the money!
Posted By: mopowergtx

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 04:44 PM

Gas is expensive. Thats right it was $50.
Posted By: Rug_Trucker

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 05:02 PM

Quote:

Gas is expensive. Thats right it was $50.




And don't forget the price od a can of Whhoopazz!

Instead of Defeo rocks? "Warning this guy owes me twenty bucks!"
Posted By: BigBlockMopar

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 05:17 PM

Quote:

.060 over bore





Why the .060 overbore?
Posted By: Qbird

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 05:59 PM

Quote:

Gas is expensive. Thats right it was $50.




What was the bet???...did I sleep through this or something?
Posted By: FuryUs

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 06:44 PM

Quote:

Why the .060 overbore?



I believe that was to unshroud the bigger Magnum valves.
Posted By: Noblewk

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 07:11 PM

Quote:

Quote:

Why the .060 overbore?



I believe that was to unshroud the bigger Magnum valves.




For a torque motor, the smaller valved 273 heads would be a better combo since the port velocity would be up. While I'll agree the Magnum Heads flow better, but for mileage you don't want to be spinning the motor in the higher RPM's.

Keep internals light, RPM's Down, and about 8 / 8.5 to 1 so you can get away with running the cheap gas (Your looking for economy). Shorty headers would be ok but not nessessary.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/12/07 07:29 PM

Quote:

Quote:

Quote:

Why the .060 overbore?



I believe that was to unshroud the bigger Magnum valves.




For a torque motor, the smaller valved 273 heads would be a better combo since the port velocity would be up. While I'll agree the Magnum Heads flow better, but for mileage you don't want to be spinning the motor in the higher RPM's.

Keep internals light, RPM's Down, and about 8 / 8.5 to 1 so you can get away with running the cheap gas (Your looking for economy). Shorty headers would be ok but not nessessary.




I figured the high swirl ports of the mag would be just as efficent as the small factory 273 ports with puny swirl and flow. Let me know if you guy think I am wrong. I think the 302 heads might be the best way to go but I don't have any sittin around.

As for the compression ratio, since higher mechanical compression generaly makes around %4 more efficency it would make up for the %3 differance in price and make a little more power to boot, that is why I say 93 octane. Spend a little more on a tank but drive a little farther on it. That would mean less stops for fuel and stop and go also hurts miledge.
Posted By: TC@HP2

Re: Super duper gas miledge 273 experiment !!! - 11/13/07 02:54 PM

I wouldn't get too hung up on spinning the engine slower just to keep fuel consumption down. You will need to match the final drive ratio to the engine combination. You will get better mileage running your engine at a reasonably built torque peak than you will be simply turning it slower. If your out of the power band, then you will have to apply more throttle, more throttle angle results in more fuel consumption, regardless of rpm involved.

The 440 in my truck will produce better mileage figures at 3200 cruising rpm , just under its torque peak, than it will at a steady state cruising rpm of 2500. But, my engine combo is built to be optimized at 75 mph, which coincides with that 3200 rpm number. That is achieved using a very small cam. To get anything smaller than most basic off the shelf variaties will require some custom grind of some sort.

I'd also figure some way to use the magnums. They are a newer head which will get better results for flow, swirl, tumble and the resulting burn than the 40 year old 273 heads. A lot more thought and effort went into those magnums than the earlier LA heads.
Posted By: Orange_Crush

Re: Super duper gas miledge 273 experiment !!! - 11/13/07 03:35 PM

I would recommend a good multi-port EFI setup. That way you would not sacrifice driveability AND it would maximize your efficiency (read power output and mileage). Perhaps you can adapt a pre-'96 Ford 4.6L setup to your needs.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/13/07 04:23 PM

The peak tq of a 273 2bbl was factory rated at 260lbft at get this... 1600 rpm. I am looking to keep the rpms low for this reason. I am also trying to figure ways to make even more tq at a lower than stock rpm. Even with this high gear combo I will still be OVER the peak tq at cruise speed of 70mph so don't get your pannys in a wad and say I need more lower gear ratio. Just trying to come up with creative ways to make this happen.
Posted By: Mr.Yuck

Re: Super duper gas miledge 273 experiment !!! - 11/13/07 04:55 PM

The 340 in my 72 Swinger gets about 17mpg hwy @ 70mph and the car runs 13.80's. Don't see why you couldn't see those numbers.

Attached picture 3949783-9cda_1.jpg
Posted By: 360view

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 12:09 PM

Some thoughts:

Read up on
"Atkinson Cycle"
"Miller Cycle"
"Delayed intake valve closing"

http://en.wikipedia.org/wiki/Atkinson_Cycle

and consider even higher static compression ratio that is compensated for by reduced 'dynamic' compression ratio.

The greater amount of expansion on the power stroke will help fuel economy. Compression ratio is also expansion ratio. Expanding 12 to 1 on the power stroke helps, even if you don't have the octane rating to do that on the compression stroke without detonation. Prius, Honda Insight, and Ford Escape engines all use these ideas to run 87 octane gasoline on 12 static compression ratio.

Calculate your average 'piston speed' with the short stroke 273 ci and then set up the highway cruise gearing to get piston speed around 1000 feet per minute and vacuum inside the intake manifold about 6-8 inches of vacuum. This is the 'island' of maximum fuel economy that stands above the 'ocean' of otherwise inferior fuel economy for most gasoline engines, when measured by pounds of fuel consumed to make a given horsepower for an hour. The 800 to 1200 foot per minute piston speed range is where friction & torque are optimum for fuel economy...above this speed range torque peaks, then volumetric efficiency peaks, then horsepower peaks but neither are best for fuel consumption.

see this complicated link for island and ocean fuel economy graphs of a TDI diesel converted to sparkplugs and running on methanol and ethanol:

http://www.epa.gov/otaq/presentations/sae-2002-01-2743.pdf

The EPA guys above use
'mean effective pressure' and rpm,
but you can use the stroke of the TDI crankshaft to convert their graph to piston speed along the bottom.

There is also a 'generalized' gasoline engine fuel economy graph in this 'classic' book by the father and son Taylors:

http://tinyurl.com/3dgkod

there is also a graph showing optimum quench area by piston diameter

Keep in mind that MPG is not dominated by engine efficiency. Most engines are nearly the same efficiency at their best spot..varying mostly on compression ratio.

To get better MPG
make tire rolling resistance lower
make aerodynamic drag lower
make mass lower
...then re-gear drivetrain to optimum horsepower for all those improvements:

A long read on MPG improvement by tire rolling resis, aero and engine eff...almost a small book:

http://tinyurl.com/kgqlz

Good luck and please keep posting on your project.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 02:30 PM

Thanks 360View! Some good reading there. The descriptions there seem to me like they want a cam ground with wide lobe seperation and then retarding it to keep the exhaust opening/closeing the same, is that how it sounds to you? The late intake closeing will definately bleed some preasure back in the intake. I would guess this forward-backward motion of the mixture around the valve would help atomize the fuel more also and provide some increase in efficency.
Posted By: RichV

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 03:42 PM

Quote:

Thanks 360View! Some good reading there. The descriptions there seem to me like they want a cam ground with wide lobe seperation and then retarding it to keep the exhaust opening/closeing the same, is that how it sounds to you? The late intake closeing will definately bleed some preasure back in the intake. I would guess this forward-backward motion of the mixture around the valve would help atomize the fuel more also and provide some increase in efficency.




I doubt this backflow will help fuel atomization. I bet it makes it really difficult to tune a carb properly. Have you ever seen how a 2 stroke with a partually plugged exhaust will spit fuel out of the carb throat even at idle? This happens even when the exhaust is free flowing enough for the engine to run at 50% power. I think fuel injection is the only way to go if you want to use the Atkinson cycle. Don't discount lean cruise either, it can't really be used by the OE due to the increase in NO emissions when running lean. It will significantly increase fuel mileage. The GM tbi software tweaked for lean cruise is readily available for free. GM tbi should be sufficient for your engine and is the cheapest way to put fuel injection on a engine. However the learning curve is much longer than with aftermarket systems.

Don't discount deep gear ratios, the Corvette gets really good fuel economy on the freeway if you can keep your foot out of it. The 2008 6 speed gets 26 mpg EPA highway fuel economy. A significant factor is really low rpm in high gear. I have a a body 8 1/4 with 2.45 gears from 1975. I have heard that some Diplomats and Fifth Avenues had 2.25 gears.
Posted By: Mr.Yuck

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 03:57 PM

I think you guys are going way overboard. a mild 318 (318 9:1, magnum heads, LD4B intake, small sumitt cam, 1.5 or 1.6 roller rockers, headers, Electronic ingnition, 600 carter), w/ a 4 speed O/D trans in a A-body w/ 3.23's should net easy 22 mpg...if you keep your foot out of it.
Posted By: NTOLERANCE

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 04:24 PM

Good luck, I love mileage experiment cars/engines. Outside the box thinking at its best. Gas will be $4.00 a gallon soon.

BUT.....

Back in the day, when there were sponsored MPG contests, mopar always sent the slant 6. At least all the ones I read about were slants.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 05:13 PM

Quote:

I think you guys are going way overboard. a mild 318 (318 9:1, magnum heads, LD4B intake, small sumitt cam, 1.5 or 1.6 roller rockers, headers, Electronic ingnition, 600 carter), w/ a 4 speed O/D trans in a A-body w/ 3.23's should net easy 22 mpg...if you keep your foot out of it.




I already get 22 mpg from a stone stock 318 2bbl with points and open chamber heads and all. If thats all I end up with I will have achived nothing.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 05:21 PM

Quote:

Quote:

Thanks 360View! Some good reading there. The descriptions there seem to me like they want a cam ground with wide lobe seperation and then retarding it to keep the exhaust opening/closeing the same, is that how it sounds to you? The late intake closeing will definately bleed some preasure back in the intake. I would guess this forward-backward motion of the mixture around the valve would help atomize the fuel more also and provide some increase in efficency.




I doubt this backflow will help fuel atomization. I bet it makes it really difficult to tune a carb properly. Have you ever seen how a 2 stroke with a partually plugged exhaust will spit fuel out of the carb throat even at idle? This happens even when the exhaust is free flowing enough for the engine to run at 50% power. I think fuel injection is the only way to go if you want to use the Atkinson cycle. Don't discount lean cruise either, it can't really be used by the OE due to the increase in NO emissions when running lean. It will significantly increase fuel mileage. The GM tbi software tweaked for lean cruise is readily available for free. GM tbi should be sufficient for your engine and is the cheapest way to put fuel injection on a engine. However the learning curve is much longer than with aftermarket systems.

Don't discount deep gear ratios, the Corvette gets really good fuel economy on the freeway if you can keep your foot out of it. The 2008 6 speed gets 26 mpg EPA highway fuel economy. A significant factor is really low rpm in high gear. I have a a body 8 1/4 with 2.45 gears from 1975. I have heard that some Diplomats and Fifth Avenues had 2.25 gears.




People tune carbs all the time with late intake valve closeing all the time, thats how most high performance motors are running any how, and they have a bunch of dilution to deal with from overlap and they have early ex opening to reduce expansion time so I don't think carb tuneing wil be that big of a deal unless I go extremely wild with this thing.

I am keeping the 8.75 for one day putting a big hp motor in it and my 2.76 is the highest gear I can find for it. I will also be keeping the TTI headers. If someone wants to donate a 4spd set up for this car I would prefer that but right now I don't have one so I can't. I am going to develop this motor in my car and when I find something suitable for the wife it will ultimately go in that, hopefully a 4dr dart or a nice station wagon.
Posted By: Anonymous

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 06:33 PM

a .060" overbore would definatly help unshroud both valves. going down to a 1.88 on the intake would help a bit, but the 1.62 exhaust is still really shrouded. I am in the process of a similar build. one major help is to lighten up the internals as much as possible. chyrsler re-used the same forged crank as the poly 318, so in order to get the smaller 273 pistons to ballance they used a wrist pin which weighs 320 grams!! Keith black has the correct length wrist pins which only weigh 107 grams. then you just have the crank ballanced, preferably by taking weight out. I have a cast crank too that i am using, but i havn't gotten around to weighing the difference.
With the notching of the block and using the stock magnum valves, the max lift you could safely run is .525", which is the max for these heads anyway. But for mileage, a big cam is not wanted obviously, but a good comp extreame cam, like the 262, would be a good 'performance' choice, and still relatively efficient.
JJ
Posted By: 360view

Re: Super duper gas miledge 273 experiment !!! - 11/14/07 10:54 PM

Yes, i do think wide lobe and then trying to keep exhaust valve opening nearer to bottom dead center.

Reversion is a problem with Atkinson style engines.

The 'Miller Cycle' is a variation of the Atkinson cycle where supercharging or turbo-charging at light boost pressures is used to reduce the reversion by keeping the intake manifold plenum at positive pressure.

The son of Mr Miller worked for Ford and was put in charge of Mazda in Japan...first American CEO

He had Mazda build a V6 with twin belt driven superchargers of the Millenia 4 door sedan:

http://www.theautochannel.com/articles/press/date/19980107/press009033.html

http://en.wikipedia.org/wiki/Mazda_Millenia

Without some boost
an Atkinson cycle engine probably could benefit from some intake manifold runner outlet size...to cylinder head intake port inlet
"Port Mismatch"
where the "stair-step" created blocks backward pulses running up toward the intake plenum. Manifold runner should be smaller than cyl head intake port opening.

Other thoughts:
...maybe some sodium filled exhaust valves like the 6.1 Hemi has to help out with tolerating high compression ratio?

Seems like the old 427 Ford exhaust valves with sodium fill are near to the correct size and length. Perhaps some Moparts tech heads know of some other sodium filled valves that are close to the right size?

Honda has a list of tricks to improve fuel economy, and the one about gently shot peening the pistons outer diameter skirts to improve oil retention is interesting:

http://www.hondanews.com/categories/837/releases/247

Mahle recently showed off an engine with some piston friction reducing coatings that I assume they can put on pistons you order from them:

http://techon.nikkeibp.co.jp/english/NEWS_EN/20071030/141572/
Posted By: Dads426

Re: Super duper gas miledge 273 experiment !!! - 11/15/07 03:08 AM

Back in the old days I was a fan of Bruce Crower's columns in Hot Rod. He discussed many topics. I found this one interesting where he built a 15.8-1 compression 350 engine and bled off cylinder pressure to a reasonable figure (see the Atkinson link above). I never saw anything else on this engine. He may have tried to market a kit for chebbies, but I'm not sure. He's working on a 6 cycle engine now Crower 6 cycle Not the easiest thing to do on a 273, but it would be a good project.

Back in the 80's I put a towing cam from Comp in my 327 Camaro/Powerglide with a Holley economaster 2 bbl and it did pretty well. Over 20 mpg on the road and the cam was torquey around town. I think the duration specs were less than stock; it ran out of steam at 4000 rpm. I would have liked to try it with a 4-speed.

Attached File
3953712-Crower002.pdf  (300 downloads)
Posted By: Rug_Trucker

Re: Super duper gas miledge 273 experiment !!! - 11/15/07 06:25 PM

Don't forget the Australian designed "negative supercharging."
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/15/07 08:33 PM

just thinking, if fuel economy is your goal, you might be better served to go with a magnum 3.9L V6, some KB167's, and a custom ground cam
Posted By: Gas_Bandit

Re: Super duper gas miledge 273 experiment !!! - 11/15/07 08:39 PM

Quote:

Over 20 mpg on the road and the cam was torquey around town. I think the duration specs were less than stock; it ran out of steam at 4000 rpm. I would have liked to try it with a 4-speed.





I am getting 20 mpg with a cammed up 327 that is a real screamer to 6200+. MAF efi. Power doesn't always have to be a sacrifice. I think by dumb luck my cruise rpm and power band ended up in a happy place.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/15/07 08:54 PM

Patrick that might be a good idea

Do they use the motor mount ears like a old LA or do they use the 3 bolts into the side like a magnum?

I think I would be limited to a custom roller cam unless the early ones had a flat tappet and either magnum style or 302 style heads and 2 bbl intakes are the only manifolds I know of. I would basically need a whole motor to start with though. And rods would have to be custom or live with the stockers. Oh and I would have to get custom headers witch really defeats the purpose of this build or make the magnum manifolds work.

The benifits however would be less surface area for friction and a few less cubes to feed. I think the rear cyls are cut off so the A-500 would fit easier being moved forward.

Any one have any more thoughts about this???
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/15/07 10:14 PM

don't know about the mounts....you'd have to look at an "la" 3.9 and a magnum one...maybe the LA has the ears, since they were put in full size trucks and vans starting in '88 (last year of the slanty is '87), and I'd find it odd that they wouldn't use common mounts for the V6 and V8....

rods? why custom? they're the same as 318 rods?

cam- hughes sells 3.9 cams, or get the stock roller reground......intake, you'd be limited to a stock LA 3.9 2bbl, one of the unobtanium MP 4bbl, or go EFI with a stocker.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/16/07 05:16 AM

The rods are different width because of the split crank throws required by the even firing order V6 it makes them thinner.

Mabey a small TBI (4.3 or 305 Chevy system or holley)could be easily tuned to run it. I think that tbi may be the best way because the fuel would have more chance to evaporate in the manifold before going in the chamber. It would also run better cold, not like I have a problem getting a carb to run cold but I may have to consider this even if I stick with the 273.
Posted By: BBR

Re: Super duper gas miledge 273 experiment !!! - 11/16/07 02:44 PM

Magnums valves will definitely bang the bore. Been there checked that.

Here's another vote for the 302 casting. Having run them on a 273, I was very pleased with their performance.

Besides, it *might* be tough to find a 0.060" over 273 piston without going custom.

I think this is a cool project and am looking forward to updates. I used to get 19-20 mpg out of my '68 Coronet, BBD 2bbl, points ignition/318/904/2.76 on the highway if I took it easy.
Posted By: 360view

Re: Super duper gas miledge 273 experiment !!! - 11/17/07 12:51 PM

The 3.9V6 idea is certainly interesting.

My bet is that the 273 V8 running slightly slower rpm would match the 3.9V8 in 'brake specific fuel consumption' because of the stroke difference and piston speed friction....but compression ratio differences will dominate.

Does a slant 6 variation have a better rod/stroke ratio that gives a slightly better force application angle at 10 degrees past top dead center? My guess is that slant 6 is slightly superior to the 3.9V6 here...but it is a small effect.

What are the pros and cons of
V6 vs I6 vs V8
in terms of detonation resistance
which is dominated by cylinder head design?

Back cylinders 7 & 8 of both LA and Magnum V8 seem to have cooling problems due to improper flow division...does the V6 have less problems and more consistent cylinder to cylinder temperatures?

Traditionally the middle cylinders of V8s that put the exhaust ports together in the center of the cylinder head have a hotspot...does the V6 have an advantage here?

For ultra high compression ratio at cruise rpm
there probably needs to be some coolant system tweaks like are explained in the last chapter of
'How to Build Big Inch Mopar Small Blocks'
.....any suggestions and ideas ?

If the line has been crossed
and other engines besides the 273 V8 are options,
why not a Motori diesel from a Jeep Liberty?

Motori also makes a V6 diesel version of the I4 used in the Liberty.....I think it can be legally brought into the USA as a tractor engine....

Motori is/was 51% owned by Roger Penske
and 49% owned by DC subsidiary Detroit Diesel...and I am not sure if Daimler retained Detroit Diesel or spun it off to Cerberus...anyone know for sure?

Keep in mind
that it is not really MPG we are after
it is Cost Per Mile
which is Fuel Cost divided by MPG.

Right now natural gas is $8 per million BTU cost.
That is about equivalent to 80 cents per gallon of gasoline, since the typical gallon of 87 octane varies in the 107,000 to 120,000 BTU per gallon range....so a million BTU's is about ten gallons worth.

Chrysler built a considerable number of Compressed Natural Gas (CNG) Magnum 5.2 V8s and sold them to US Federal Agencies during the mid 1990s. Many of these CNG 5.2 V8s are now in junk yards.....but these are justly famous for blowing plenum gaskets if there is a backfire on the intake side of the engine. Perhaps a MPI intake manifold would cure this?

I suspect that for the next ten years or so natural gas will be the least expensive fuel that can be used in vehicles relatively easily. Honda sells a CNG Accord you can test drive along with a home compressor kit to fill the tanks at your own home.

Coal is only about $2 per million BTU.
That is equivalent to 20 cents per gallon gasoline.

My grandfather built and ran a 'water gas shift reactor' kit using Council of Fuel Research plans (CFR was the for runner to the US Energy Department) during World War II. This device mounted on the rear bumper and turned coal/charcoal/coke into carbon monoxide gas (highly poisonous if not confined and even small amounts impair driving behavior) mixed with hydrogen gas (the H2 gas has most of the BTU) which was then fed to the engine for sparkplug ignition. A computer controlled version of this with an oxygen sensor to control air to fuel ratio would work even better than the 60 year ago technology. Somewhere, probably at the South African company SASOL there is an engineer who could design this modern version to work effectively.
Posted By: Clair_Davis

Re: Super duper gas miledge 273 experiment !!! - 11/17/07 03:10 PM

The I4 Motori diesel from the Liberty will/should bolt up to a small block trans. Ditto on a 3.7L V6 from the Liberty (and probably others). Matching the converter to the crank would be another issue, but shouldn't be much different than a new Hemi. Of course that's not the same as sneaking mileage out of a 273. W/O going to injection, it's going to be tough to maximize steady-state cruising mileage unless you REALLY sort out the steps on the rods in a TQ to give a 16-17:1 AFR at light throttle cruise. I suppose it CAN be done, but I never have heard that it HAS been done. OEM's never went there because converters don't work efficiently at those AFR's and emissions go up.

Clair
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/19/07 12:58 PM

Quote:

The 3.9V6 idea is certainly interesting.

My bet is that the 273 V8 running slightly slower rpm would match the 3.9V8 in 'brake specific fuel consumption' because of the stroke difference and piston speed friction....but compression ratio differences will dominate.





what stroke difference? the 273 is a 3.625" bore by 3.31 stroke, the 3.9 is a 3.91" bore, 3.31 stroke?

Oh, and hotroddave, it looks like the 3.9 never had ears for engine mounts, just the 3 bolt holes, even the LA version according to this site http://www.mopar1.us/sort.html
but then that might be a blessing, as you could build brackets to mimic the ears out of some 3/8 or 1/2" steel and put the motor just about anywhere you want....

I still personally think the very minimal gains of the smaller displacement of a 273 will not be worth it given the cost of parts (trying to find 0 deck 273 pistons), vs building up a roller 'teen.....UNLESS you can maybe use stock low comp pistons and a longer aftermarket shivvy rod (6.25"?) to get your 0 deck....
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/19/07 02:36 PM

Last night someone suggested useing a 360 crank turned down. I haven't had time to crunch the numbers but I might be able to use stock 273 2bbl pistons.

However one thing I do want to do is make something every one can copy if it works out, thats why the small block, mabey a 318 would be better for this purpose cuz every one has one. I don't want to run a slant becuse there is no closed chamber heads and I would have to swap a bunch of stuff to run it in my car, like exhauset and motor mounts.
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/19/07 04:43 PM

if you want easy to replicate and economical (from a fuel consumption and cost standpoint), then I'd definitely start with a roller teen, KB167 pistons, probably stock rods (I really don't think lighter rods would help mileage that much), mag or 302 heads, performer intake w/small t-quad, & headers. for a cam I'd look at the comp 254HR or XR258HR....
Posted By: dulcich

Re: Super duper gas miledge 273 experiment !!! - 11/19/07 05:39 PM

I remember reading about the Crower engine back in the '80's Hot Rod Magazine. It made very poor power and when the put it in a car, can't recall if it was a steet rod or and El Camino, it got nothing special as far as mileage.
Posted By: Prince_Valiant

Re: Super duper gas miledge 273 experiment !!! - 11/19/07 06:28 PM

Here's how I'd build a super-duper mileage old mopar w/v8 (let's face it...a slant would be a better endeavor for mileage...but should you want a slant, apply much of what is here to it):

Start with the lightest available platform with easy access to parts...for a v8, the 64 A-body comes to mind.

Weight is CRUCIAL, especially with city mileage, and important out on the hwy...grades, minor acceleration, rolling ressistance are all heavily influenced by the weight of the plat-form you are using.

Another reason size is important, is that it is the second most important aspect when determining WIND RESISTANCE (speed is most important).

But going this way, you are minimizing the two most important things with regards to fuel mileage.

Face it, cruising at a steady speed, you need to apply as much hp as there is ressistance (more and you accelerate, less and you lose speed). When HP=rolling resistance+Wind resistance, you have steady state cruise. Increase speed, Wind resistance goes up exponentially, HP demands go up too. Increase weight, and you effect rolling resistance, AND you increase the amount of work needed to accelerate to speed, and to ascend hills either slight or great.

And HP will take a relative amount of gas and air...since really, that is the "work" that HP is calculating.

Given it's a v8, I'd go with the 318. In the ideal world, a 273 WILL have greater operational efficiency at a given speed/rpm/HP demand, but I think that this is more than off-set by parts availability and price.

Given this, and in keeping weight in mind: I'd build a roller 318 with eddy AL heads.
Give me 10.5:1 compression
Eddy AL heads (reduce pumping losses, relatively small ports will maintain intake velocity, wt loss)
Performer or LD4B intake (wt is the key here)
Eddy 500 carb ( tuned to idle as lean as possible, cruise on a slight hill with as little lean surge as possible...I'd aim for roughly 15-15.5:1 AFR).
HYD roller cam specing ~192-196 @ .050, roller 1.6:1 ratio rockers. Ideally lift in the .480 range.
1 5/8th headers
2.5 inch dual exhaust with an X-pipe.
Electronic ignition running 14 degrees initial, probably 34 total, in by 2200rpm...and as much vacuum advance without pinging.

For the tranny, I'd source an AL OD 833 (light weight and more efficient). For the rear end, I'd source a 7 1/4 rear with 2.94 gears for a 2.2 final drive ratio (lighter rear/gears/axles reduce losses/rolling resistance on several fronts...the closer to 1:1 a gear is, the more efficient it is with regard to frictional losses.)

I'd probably get an underdrive pulley set, have manual steering and no AC. I'd use a clutch fan too. A slant six radiator would have to do the job. Run a 205 degree thermostat. Heck, I'd even run a small battery to reduce weight.

Make sure the wheel/axle bearings are in good working order and adjusted correctly. I'd probably WANT 4 wheel drum brakes to reduce any drag on the wheels too.

For tires, I'd run what the insight runs...bridgestone potenza re92 (iirc)...very low rolling resistance. Inflate to 50psi (it's safe, however not recommended).

See where else you could lose weight. Run thin 5-30W synthetic oil too.

The gears/OD combo I selected because of the reasons I had posted elsewhere:
Quote:

by Prince Valiant

While it's true, you shouldn't go with the lowest gear available/possible, you shouldn't try to target the torque peak either.

You are correct that the torque peak represents the point of greatest volumetric efficiency...this is, however, on a dyno. Cruising presents a different dynamic. You want to generate greater volumetric efficiency, and that is through gearing.

Here's an example of what I'm talking about:

Let's say I've got a car, and I'm driving roughly 60mph. I've got a tire with an outside diameter of 25.6 inches (245/60R14). My car has a 440, that at 100% VE makes 500ft-lbs of torque (these are just given, any number or representation will illustrate what I'm trying to demonstrate)

Now, for arguments sake, let's say it takes approximately 30HP to cruise at 60MPH, once you account for wind ressistance, rolling ressistance (we are, of course, negating other parasitic loses that are either equal b/w the two examples, or at this point unimportant for this demonstration).

Now, say I've got 3.55 gears, and a 1:1 final drive ratio. According to the math, I should be roughly traveling at 2800rpm at 60mph.

Let's do the math on my VE then: IF it takes 30HP to maintain 60mph, and 60 mph translates to 2800rpm then:

(30hp/2800rpm)x5252=56.2ft-lbs of torque that my engine is generating to maintain this cruise speed.

If at 100%VE my engine makes 500ft-lbs of torque, then at this speed, I can calculate that my engine is operating at 56.2/500=11.2% VE.

Now, say I swapped in 3.23 gears AND put a OD in the thing with a 0.69 ratio like the a-518. This brings my final drive ratio to 2.28:1

Same speed as above, it'll take the same HP to go down the road....30HP. But, now my engine lugs along at a relatively low 1800 rpm's.

Now again, the math:

(30hp/1800rpm)x5252=87.5 ft-lbs of torque.

To generate that same HP at a lower rpm, I've now got to generate MORE torque. And, since I generate more torque...I'm operating at a higher VE! In this case, I'm now going along at a 87.5/500= 17.5% VE vs the 11.2% earlier.

This higher VE also comes with higher cranking compression, so you are getting the most out of the fuel you put in there too (since it requires more air and fuel/PER ENGINE REVOLUTION to generate higher torque...but this is offset by the significantly less engine revolutions per mile)

This is why cruising is different. Sure...if your engines peak torque is 4500+rpm, you won't do yourself many favors by going with uber low ratios...but, targeting torque peak isn't the way to go either.

On top of the greater VE, you also have to account for the fact that lower rpm's per mile means less frictional losses (approximately 36% less in the example above) as the pistons don't travel as far, the bearings don't cover as much ground, and the engine accessories (water pump, power steering, altenator, AC if applicable) are turning fewer revolutions/mile. AND you get less frictional/reciporacating losses because not only is the engine turning less, but many of the pieces of the tranny is turning less, if a low rear gear is used, the driveshaft is turning less too. All these things require work, and you make less of it per mile with higher gears.



The above, are the same reasons why bigger engines don't do as well (less operational VE...but the difference b/w a 273 and 318 are small, and more than offset by the ease of piston/head/roller cam availability of the 318 over the 273).

The car I specify above would easily, tuned well, imo get over 30mpg.
Posted By: autoxcuda

Re: Super duper gas miledge 273 experiment !!! - 11/19/07 07:19 PM

Quote:

Here's how I'd build a super-duper mileage old mopar w/v8 (let's face it...a slant would be a better endeavor for mileage...but should you want a slant, apply much of what is here to it):

Start with the lightest available platform with easy access to parts...for a v8, the 64 A-body comes to mind.

Weight is CRUCIAL, especially with city mileage, and important out on the hwy...grades, minor acceleration, rolling ressistance are all heavily influenced by the weight of the plat-form you are using.

Another reason size is important, is that it is the second most important aspect when determining WIND RESISTANCE (speed is most important).

But going this way, you are minimizing the two most important things with regards to fuel mileage.

Face it, cruising at a steady speed, you need to apply as much hp as there is ressistance (more and you accelerate, less and you lose speed). When HP=rolling resistance+Wind resistance, you have steady state cruise. Increase speed, Wind resistance goes up exponentially, HP demands go up too. Increase weight, and you effect rolling resistance, AND you increase the amount of work needed to accelerate to speed, and to ascend hills either slight or great.

And HP will take a relative amount of gas and air...since really, that is the "work" that HP is calculating.

Given it's a v8, I'd go with the 318. In the ideal world, a 273 WILL have greater operational efficiency at a given speed/rpm/HP demand, but I think that this is more than off-set by parts availability and price.

Given this, and in keeping weight in mind: I'd build a roller 318 with eddy AL heads.
Give me 10.5:1 compression
Eddy AL heads (reduce pumping losses, relatively small ports will maintain intake velocity, wt loss)
Performer or LD4B intake (wt is the key here)
Eddy 500 carb ( tuned to idle as lean as possible, cruise on a slight hill with as little lean surge as possible...I'd aim for roughly 15-15.5:1 AFR).
HYD roller cam specing ~192-196 @ .050, roller 1.6:1 ratio rockers. Ideally lift in the .480 range.
1 5/8th headers
2.5 inch dual exhaust with an X-pipe.
Electronic ignition running 14 degrees initial, probably 34 total, in by 2200rpm...and as much vacuum advance without pinging.

For the tranny, I'd source an AL OD 833 (light weight and more efficient). For the rear end, I'd source a 7 1/4 rear with 2.94 gears for a 2.2 final drive ratio (lighter rear/gears/axles reduce losses/rolling resistance on several fronts...the closer to 1:1 a gear is, the more efficient it is with regard to frictional losses.)

I'd probably get an underdrive pulley set, have manual steering and no AC. I'd use a clutch fan too. A slant six radiator would have to do the job. Run a 205 degree thermostat. Heck, I'd even run a small battery to reduce weight.

Make sure the wheel/axle bearings are in good working order and adjusted correctly. I'd probably WANT 4 wheel drum brakes to reduce any drag on the wheels too.

For tires, I'd run what the insight runs...bridgestone potenza re92 (iirc)...very low rolling resistance. Inflate to 50psi (it's safe, however not recommended).

See where else you could lose weight. Run thin 5-30W synthetic oil too.

...




I like that with the 64.

I think the cost of the eddy heads defeats the project. And I thought they had big valves.

From the chassis department I'd add:

light aluminum rims 14" (15" weigh more)
Gibbs synthetic diff fluid 10/30 weight equivalant
Same thin gear lube in trans
Some home made cold air induction tube
Lower the car some to reduce drag and keep air from getting under it
Spitfire headers to reduce weight
Aluminum master cly.
If you need a radiator allready get an aluminum one
Bucket seats off a later model car. They should weigh a lot less than a 64 bench seat. Don't get fancy ones that are heavy

Do later 7 1/4 rears have straight roller bearing instead of tapered ones? Or do they all have roller bearings? Roller green type bearing should have less resistance.
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/19/07 07:44 PM

the 7.25" in my '76 duster uses a sealed roller bearing w/o adjustment, so it has to be a straight roller or ball bearing...I can't remember which at the moment.
Posted By: RichV

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 04:32 PM

Quote:


For the tranny, I'd source an AL OD 833 (light weight and more efficient). For the rear end, I'd source a 7 1/4 rear with 2.94 gears for a 2.2 final drive ratio (lighter rear/gears/axles reduce losses/rolling resistance on several fronts...the closer to 1:1 a gear is, the more efficient it is with regard to frictional losses.)





A four speed with a direct drive high gear is more efficient than a overdrive trans. You can get a 2.2 something ring and pinion out of a M body. You can swap a 3.09 low gear, direct drive high gear set into a aluminum case if you want the weight savings.
Posted By: myduster360

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 05:17 PM

Quote:

Fuel Inject it. That way you can use lean cruise.






A fresh rebuilt 318 Magnum MPI + A500 would seem like the most economical choice overall. Especially if you are including all the added costs of new parts.
The 318 Magnum already has:
Small high velocity/low friction hyd roller cam
fast burn, efficient combustion chamber
light pistons
Long ram intake
low drag 1.5mm piston rings
Very good Low RPM torque

Lean cruise it at around 16-17:1 A/F. I think 25-28mpg highway could be expected. You might get even better if can play with the PCM ignition timing via a SCT flash or the like.
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 05:28 PM

You guys with your Magnums and 302's. Nothing wrong with the stock 273 head. You can get some good flow numbers out of those heads not to mention port velocity. He can also play around with head gasket thickness to fine tune the CR.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 05:53 PM

Manual trans is out of the question unless someone wants to donate a complete set up. I think with this low powerd motor the early dakota 5spd should fit and work best. The a-500 has a higher OD ratio and the trucks with them don't seem to get much if any worse miledge than the 5spds, but I would prefer the 5 spd personaly they are more fun to drive.

The original 273 heads are not hardened seats. The 302 has more swirl and velocity in it also. I am torn between the 302 and MAG right now.

I am in the process of moveing right now so I have not started yet, just gives me more time to plan. Keep the ideas flowing.
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 08:38 PM

I have flow number that show the 273 heads will outflow the 302. As far as hardened seats, unless you are towing and running that 273 hard and lean you don't need hardened seats. Pulled the heads off my 273 with 75,000 miles and no valve recession. 67 Dart, 273/Carter 625, electronic ignition, duel exhaust with Flowmasters, Comp 268 cam with 904 and 3:23's drove from NW to LA and back with an average of 22 MPG at average 64 MPH.
Posted By: dmerc

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 09:10 PM

My 273 headed 318 was getting 22MPG with 2.94 gears in my Duster. The early closed chamber 273 heads are a good choice for a gas mizer set up.
Posted By: Anonymous

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 09:14 PM

rig it up to go nuclear!!would last a lifetime.......
Posted By: feets

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 09:53 PM

I'll skip quoting all the "Prince Valiant" stuff but I do have to take exception with it.
He did lots of work with numbers to show his theories. The real world blows a great big hole in it because torque production is not linear. Efficiencies of individual parts vary greatly with engine speed. The whole package will swing widely as the engine accelerates through the rpm range.

As for super stupid-low gearsets, you're killing your mileage.
How many of you have a 2.2 or 2.4 geared M-body that gets better than 15 mpg in the city? It doesn't happen because the car has to work so hard to overcome the lack of torque multiplication during acceleration.
Seteady state cruising is great but you've got to get up to speed first.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 10:13 PM

I had a 318 87 150 longbed pickup with 2.94 gears and I got 16 in town. It had taller tires so it was more like a car would with 2.20 or 2.45 gears and more weight. And for the highway it would get 19-20 and it only had a 3spd 904 and worse aerodynamics. With a more optimized engine and drivetrain I really don't think 20 in town and even 30+ on the highway is too much to ask for(with sane driving habits and a few other car tricks).
Posted By: SlotCarWon

Re: Super duper gas miledge 273 experiment !!! - 11/26/07 11:28 PM

This discussion has been interesting but increasing fuel economy is very difficult.
There are only two things to do to reduce fuel consumption:
1) reduce the work you are asking the engine to do
2) make the eninge more efficient

So all of the ideas to reduce the work of the engine; lighter wheels, reduced aero drag, manual trans or lock-up TQ are good ideas and will result in improved fuel consumption no matter what is done to the engine.

The real problem is that actual fuel economy may not be effected even if the engine is more "efficient". This is because most of the time the engine is operated in a part throttle mode. It is very difficult to improve part throttle fuel economy because as the engine is made more "efficient" the throttle position changes (closes) which causes the engine to overcome more pumping work (the work the engine needs to overcome to suck air past a partially closed throttle plate). It's one of those things that you take 3 steps forward with say compression ratio and 2.5 steps beck due to an increase in the pumping work, so the 10% efficieny improvement becomes 2% or less and this is just not seen when driving the car.

Idle fuel consumption is pretty much based on engine speed with fuel/air ratio also a part, so the lower the idle RPM and the leaner the lower the fuel consumption will be.

Engine-wise I suggest keeping it simple; use a high compression ratio for thermal efficiency and a low overlap cam for good idle at a low RPM with a lean idle carb setting, with this you might be able to see an improvement with fuel economy.
Any other thing you can do to reduce the engines work should also show an improvement in fuel economy.
Posted By: Prince_Valiant

Re: Super duper gas miledge 273 experiment !!! - 11/27/07 12:29 AM

Quote:

I'll skip quoting all the "Prince Valiant" stuff but I do have to take exception with it.


Oh no...please quote your "exceptions".

I think one of the things people lose with "my" so called "theories" (which aren't really mine and are fairly well used in cars today...just look at how far down they get final drive ratios in this day and age) is people keep coming back with "throttle posistion" as if they believe that generating increased torque at a given speed will require a throttle that's opened further...thus putting more fuel down in the engine.

Couldn't be further off from what would actually happen.

Again, let's give a general example:

My car requires 30HP to travel down the road @ 60mph.

Doesn't matter if that's 30HP @ 3000 rpm or 30HP @ 2000rpm. It's just 30HP.

Now, HP is simply work. In this case, we can quite literally view it as the amount of air/fuel moving into and out of the cylinder at a given rate. So whether my engine is spinning 3000rpm at 30HP or 2000rpm, at the end of a minute, assuming NO friction within the engine, I will move ~ same amount of air and fuel within a given time period.

Given this (oh, and feets, please feel free to quote away should you disagree...otherwise, don't single me out again!), one can reasonably assume that the throttle posistion will be the same in either example.

Of course, it's NOT exactly the same...and this is NOT all that important. Why? because if my engine is spinning 3000rpm in a given minute, I'll generate more vacuum. More vacuum means that my carb is either going to flow MORE at a given throttle posistion, or to flow the amount to supply a given air/fuel demand, it'll take less throttle to flow the same amount (we know this is true...this is why vacuum info is given with flow data. A head will flow greater at 28mm/HG than at 20mm/HG, will it not? Don't you think it's the same with a carb?).

And still, do you think it's easy to turn an engine over? Try doing it by hand just once! That's a lot of work you've got to do just to overcome friction. Now, turn it over 1000 times in a given mile. Not easy is it? Of course, you remove all that work by gearing it lower and instead of turning 3000 revolutions per mile, you gear down and turn 2000revolutions per mile. And that's a significant amount of fuel you save by not doing this work.

Even by reading your "objections", I am not so sure you even read my post.
Posted By: myduster360

Re: Super duper gas miledge 273 experiment !!! - 11/27/07 06:10 AM

Question Prince,

If the engine is using EXACTLY the same mass flow rate of fuel,(more fuel per cycle at lower rpms), how does RPM really make any difference???

In your over generalized 440 example at either 2800rpm or 1800rpm it still consumes about 14 lb/hr of gas. Correct?? You stated: "Doesn't matter if that's 30HP @ 3000 rpm or 30HP @ 2000rpm. It's just 30HP.....I will move ~ same amount of air and fuel within a given time period." So to make 30hp, you need 14lb/hr of fuel, wether you have a 440, 318, 2.2l, or 600cc. If gas weighs 6 lb/gal, your gas tank is STILL draining by at least 2.3 gal/hr regardless of the engine or its rpm.

Answer: By your arguments engine RPM(or even engine displacment) doesn't affect the rate of fuel consumption. You've talked yourself in circles because neither is actually true.

imo, you either really don't know what you're talking about or you're over generalizing and simplifing to the point of confusing yourself and others. I honestly think its the latter. Mainly because i agree with your general conclusions, but your reasoning and rational for them barely hold water. i suggest more work with the caculator before typing.

I've said it before and now agree with feets, torque vs VE isn't a straight line. Your VE example/argument is worthless.

BTW mechanical eff(friction)is a much greater % of total engine eff as rpm drop. So the thermal eff and ve both usually have to rise to maintain the same output, which is usually very unlikely given your argument for static throttle position. At a constant load friction doesn't rise nearly as quickly with rpms as VE and TE

One more thing, regardless if you're right or not, no one will respect your opinion of you're being a jerk.
Posted By: feets

Re: Super duper gas miledge 273 experiment !!! - 11/27/07 04:17 PM

PV... What's the deal? Wy get all fussy about what I wrote when you didn't even address it in your post?

I said that VE is not linear. That remains true.
I didn't knock your work. Instead, I pointed out a simple flaw.
You've got lots of info but when one little thing goes awry, it throws out everything related to it. Think of it as working a 6 page math problem then dividing by zero. OOPSIE! There goes all that work.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/27/07 06:30 PM

Please guys don't get my thread locked! Focus on the subject, you guys are all thought provokeing and I apreciate every ones thoughts and input.
Posted By: MarkZ

Re: Super duper gas miledge 273 experiment !!! - 11/27/07 06:57 PM

Quote:

Given this, and in keeping weight in mind: I'd build a roller 318 with eddy AL heads.
Give me 10.5:1 compression
Eddy AL heads (reduce pumping losses, relatively small ports will maintain intake velocity, wt loss)
Performer or LD4B intake (wt is the key here)





I don't get this combo right here. Eddy heads have the larger 340/360 ports, and 2.02 intake valves. Even with the 318 port size of the LD4B up top, the larger volume further down the line will still kill port velocity. This would seem very counter productive to me in trying to make mileage.

302 heads get my vote if you're going to use a 318. If the 273, then use the heads off of that motor. You have to keep velocity up not only in the intake, but all the way into the cylinder.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 11/27/07 07:55 PM

The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...
Posted By: GO_Fish

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 02:24 AM

you could probably find someone on here to swap you a set of Mags for 302's. They'd probably jump on it!
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 05:58 AM

Quote:

The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...




I called my buddy that owns the flow bench. He recalls the velocity was greater on the 273 head vs the swirl port. He's going to pull it up on the computer and I'll post the numbers. Also remember that with the magnums you'll need the corresponding valve train and intake in order for the heads to work. There will be a lot of port mismatch with a Magnum/273.
Posted By: Clair_Davis

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 12:56 PM

At what point does good swirl/tumble/mix become more important than just velocity? If we're talking a couple % faster in a 44-year old head vs. a 24-year old head, I choose the newer one every time.

Clair
Posted By: Rug_Trucker

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 01:12 PM

We'll need to keep this thread rolling as Dave is moving to Montana today. Unless plans have changed.

I think he's going to raise himself up a crop of dental floss..........

Safe trip Dave and family!
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 04:35 PM

another thing to consider, I've read the closer the valve is to the cylinder side, the more swirl is induced from that shrouding. on a 273, anything larger than the stock 1.78/1.5 valves require bore notching to avoid a collision between the valve and cylinder bore, so the shrouding effects will probably be about the same regardless of head/valve size. on a 318's 3.91" bore, the magnum's 1.92/1.625" valves may give them an additional boost in induced swirl over a 273 head or '302 head with the small 1.78/1.5 valves...

I'm still not convinced the 273 will give any significant mileage improvement over a similarly built 318. for cost and ease of parts aquisition, I still think a 318 (roller cam block) is the way to go, especially if trying to optimize power and economy.
Posted By: BBR

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 05:09 PM

What 273 heads does he have? Open chamber 67-69's or the earlier closed chamber models with the funky bolts?

If it's the open chamber, I certainly go with the 302's just for the sake of squeezing a better CR out of the thing with minimal hassle.

I would think as far as rear end ratio goes, you would want to choose it (and your tire size) so that your target cruise rpm equals your peak torque rpm, eh?
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 05:54 PM

Quote:

Quote:

The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...




I called my buddy that owns the flow bench. He recalls the velocity was greater on the 273 head vs the swirl port. He's going to pull it up on the computer and I'll post the numbers. Also remember that with the magnums you'll need the corresponding valve train and intake in order for the heads to work. There will be a lot of port mismatch with a Magnum/273.




Here are the numbers off my head. i tried to scan the test data but it wouldn't show in color and was impossible to read. I'll try and explain what is depicted on the sheet.

Used a 302 Swirl port vs the stock 273.
both had the same modifacations except we stayed with the stock intake size on the 302 and only modified with a stainless valve.
The 273 used a cut 1.88 stainless valve down to 1.84. We found this size ideal for the 273 to prevent shrouding.

First test

273 with a 1.84 intake, 1.56 exhaust with alittle bowl work Same on the 302 except larger intake and exhaust valve.
113% max velocity on both heads

2nd test

273 head with same mod with the addition of more port work, 70 degree bowl cut and 3 angle valve job. 302 the same, both had Ferra valves

Gained 116% on the 273 and 115% on the 302

1st test

The flow numbers showed a big differance with the 273 showing max flow of 166.9 cfm at .400 of lift with the flow curve remaining steading and not falling off until .475 of lift.

The 302 however showed a max of 161.8 and started to fall off at around .500 lift

2nd test

273 showed 169 cfm at .450 lift where the 302 showed 163 cfm at .450 then dropping off.

273 and 302 had the same modifacations.
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 08:51 PM

Quote:

Quote:

Quote:

The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...




I called my buddy that owns the flow bench. He recalls the velocity was greater on the 273 head vs the swirl port. He's going to pull it up on the computer and I'll post the numbers. Also remember that with the magnums you'll need the corresponding valve train and intake in order for the heads to work. There will be a lot of port mismatch with a Magnum/273.




Here are the numbers off my head. i tried to scan the test data but it wouldn't show in color and was impossible to read. I'll try and explain what is depicted on the sheet.

Used a 302 Swirl port vs the stock 273.
both had the same modifacations except we stayed with the stock intake size on the 302 and only modified with a stainless valve.
The 273 used a cut 1.88 stainless valve down to 1.84. We found this size ideal for the 273 to prevent shrouding.

First test

273 with a 1.84 intake, 1.56 exhaust with alittle bowl work Same on the 302 except larger intake and exhaust valve.
113% max velocity on both heads

2nd test

273 head with same mod with the addition of more port work, 70 degree bowl cut and 3 angle valve job. 302 the same, both had Ferra valves

Gained 116% on the 273 and 115% on the 302

1st test

The flow numbers showed a big differance with the 273 showing max flow of 166.9 cfm at .400 of lift with the flow curve remaining steading and not falling off until .475 of lift.

The 302 however showed a max of 161.8 and started to fall off at around .500 lift

2nd test

273 showed 169 cfm at .450 lift where the 302 showed 163 cfm at .450 then dropping off.

273 and 302 had the same modifacations.




what bore was that tested on, a 273 bore, or a 318 bore, or a 4" (360) bore?
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/28/07 08:56 PM

Not sure on your question. are you referring to the plastic plate the head is bolted to? if so it wouldn't make a differance since it's a measurement of the head in and out.
Posted By: patrick

Re: Super duper gas miledge 273 experiment !!! - 11/29/07 01:17 PM

when heads are flowed on a flow bench, they're allways bolted down to a bore plate simulating the cylinder sidewall, and yes, it will make a difference in flow, as the valve gets closer to the cylinder wall, it will be shrouded more, and recorded flow will drop. IIRC Ryan J did a flow test of a set of heads on like a 4.25" bore plate and the same heads on a 4" bore plate, and he saw over a 10% decrease in flow between the tests, IIRC.
Posted By: myduster360

Re: Super duper gas miledge 273 experiment !!! - 11/29/07 01:36 PM

Quote:

At what point does good swirl/tumble/mix become more important than just velocity? If we're talking a couple % faster in a 44-year old head vs. a 24-year old head, I choose the newer one every time.

Clair






Absolute Velocity(cfm) is a very small factor when attempting to judge combustion efficiency.

I did some cylinder head development with Cummins in college and they actually measure "SWIRL TORQUE" in the cylinder to judge comb eff. This quantifies exactly how fast the air is swirling around once in the cylinder. An increase "swirl torque" had a significant impact on comb eff, but was somewhat independent of absolute port velocity ei: more HP, more mass air flow and less HC emissions from the same CFM.

In the last 20years steady state CFM has become an increasingly less significant design aspect of new OEM cylinder heads.

Bottom line: When in doubt always go with the newer designed head.
Posted By: Prince_Valiant

Re: Super duper gas miledge 273 experiment !!! - 11/29/07 07:54 PM

Quote:

when heads are flowed on a flow bench, they're allways bolted down to a bore plate simulating the cylinder sidewall, and yes, it will make a difference in flow, as the valve gets closer to the cylinder wall, it will be shrouded more, and recorded flow will drop. IIRC Ryan J did a flow test of a set of heads on like a 4.25" bore plate and the same heads on a 4" bore plate, and he saw over a 10% decrease in flow between the tests, IIRC.


I think he was just pointing out that with the same valve size b/w the 273 heads and 318 #302 heads, even if the flow is affected (which it is), it would affect both heads the same, so the comparison is valid.

However, I agree, anytime flow is tested, I like to know the bore size
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/29/07 09:17 PM

I'll have to ask. He stopped by yesterday with the printout. Since I was there when he did the test I do know he used the same bore plate. Just for information the heads I put on the 273 had a bit more work than the heads he used for the comparrison test. My heads had a 70 degree bowl cut with a lot of blending and removing any sharp edges, removed sharp edges on int. and exh ports. Did a short turn radius cut around valve guides and a 30,45,60,70 degree cut on the intake valve (1.84) and a 15,45,60,79 on the exh. Used Ferra valves. Got 116% max velocity and they flowed 169.1 cfm at .500 of lift.
Posted By: dmerc

Re: Super duper gas miledge 273 experiment !!! - 11/29/07 09:28 PM

This is an interesting thread. I have 273 heads on a 318 Duster. Has identical mods as yours and I ran a 15.9 (at 5000ft) with it. My next project is a 318 Volare that I'm going to put 273 heads on. I'm going to use the 2 barrel single plane intake that goes with the 273 heads and see what kind of mileage I can sqeeze out of it. I just like those 273 heads! They are lighter too and they don't seem to crack or warp like the 302's
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/30/07 12:22 AM

Quote:

This is an interesting thread. I have 273 heads on a 318 Duster. Has identical mods as yours and I ran a 15.9 (at 5000ft) with it. My next project is a 318 Volare that I'm going to put 273 heads on. I'm going to use the 2 barrel single plane intake that goes with the 273 heads and see what kind of mileage I can sqeeze out of it. I just like those 273 heads! They are lighter too and they don't seem to crack or warp like the 302's




I have a good friend and engine builder that is a class racer. He raced a 273 car years back and now races a 340 Duster. One can actually make the 273 scream. there's a Stock Eliminator racer by the name of Wong that races 273 cars and gets them into low numbers.
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 11/30/07 02:21 AM

Quote:

Quote:

Quote:

Quote:

The 273 heads will have less velocity because they have a slightly larger port volume. Not that they would be a bad choice for that reason, they would make less pumping losses. That is also a reason for me to consider the magnums, I have a set of them and the 273 heads but no 302s...




I called my buddy that owns the flow bench. He recalls the velocity was greater on the 273 head vs the swirl port. He's going to pull it up on the computer and I'll post the numbers. Also remember that with the magnums you'll need the corresponding valve train and intake in order for the heads to work. There will be a lot of port mismatch with a Magnum/273.




Here are the numbers off my head. i tried to scan the test data but it wouldn't show in color and was impossible to read. I'll try and explain what is depicted on the sheet.

Used a 302 Swirl port vs the stock 273.
both had the same modifacations except we stayed with the stock intake size on the 302 and only modified with a stainless valve.
The 273 used a cut 1.88 stainless valve down to 1.84. We found this size ideal for the 273 to prevent shrouding.

First test

273 with a 1.84 intake, 1.56 exhaust with alittle bowl work Same on the 302 except larger intake and exhaust valve.
113% max velocity on both heads

2nd test

273 head with same mod with the addition of more port work, 70 degree bowl cut and 3 angle valve job. 302 the same, both had Ferra valves

Gained 116% on the 273 and 115% on the 302

1st test

The flow numbers showed a big differance with the 273 showing max flow of 166.9 cfm at .400 of lift with the flow curve remaining steading and not falling off until .475 of lift.

The 302 however showed a max of 161.8 and started to fall off at around .500 lift

2nd test

273 showed 169 cfm at .450 lift where the 302 showed 163 cfm at .450 then dropping off.

273 and 302 had the same modifacations.




what bore was that tested on, a 273 bore, or a 318 bore, or a 4" (360) bore?




Got an answer for you. They were tested on a 4" bore plate
Posted By: Clair_Davis

Re: Super duper gas miledge 273 experiment !!! - 11/30/07 04:04 AM

Quote:

I think he's going to raise himself up a crop of dental floss..........




I hope he saves the wax...

BTW, I hate to ask a pretty basic question this late in the thread, but what exactly is this "115% max velocity" stuff referring to? I guess I haven't seen this terminology before...

Clair
Posted By: 360view

Re: Super duper gas miledge 273 experiment !!! - 12/05/07 12:47 PM

for a
"SuperDuper MPG experiment"

wouldn't the octane tolerance of a cylinder head and piston crown combination be more important than any swirl numbers?

I know swirl can improve fast burn,
and fast burn can improve octane tolerance,
but the stuff I have seen
says that 'old fashioned' quench area works better
but that modern cylinder heads have had to cut
back on quench area due to pollution concerns related to NOx

Porsche engineer May's HE "Fireball" high quench area head for Jaguar's V12:
http://www.jagweb.com/jagworld/v12-engine/page3.html

Larry Widmer's 'Soft Head' article (aka TOO or "The Old One")

http://www.theoldone.com/articles/The_Soft_Head_1999/

the Aussie view of pinging & detonation:

http://autospeed.com/cms/A_0601/article.html
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! UPDATE - 01/02/08 03:10 AM

Well I picked up a 318 block today and was going to have it zero decked and use some 68 style stock pistons and 340 rods. I carried it all to the machine shop to mill a bunch off the deck and the guy gave me a really good super dooper screaming deal on a set of KB 167 pistons .030 over so I will be useing this short block with the SCAT I beams from my busted stroker. The pistons are 100g lighter a piece and the rods were 115g lighter each, also I should lose even more weight from balancing it and make a very light rotateing assy. It should be easy enough for every one to copy also.

For the top end I am going to put on some 302 heads, I have not decided if I am going to put in some 1.88 valves I have around here but there won't be much porting going on. Mabey put on a groove in the chambers for good measure

For a cam I have a 273 2bbl solid cam lifters and rockers I will use.

I have an LD4B or Holley street dominator to pick from. I am still hopeing to find a offy dual port

I will run a small Thermo-quad and my car already has TTI headers so soon I should have this thing goin. I will probably drive it like this for a little bit before I put in an OD trans. It has 2.76 gears right now.

Any one want to venture what improvement just the motor will give me from my stock 68 318 2bbl?
Posted By: Gas_Bandit

Re: Super duper gas miledge 273 experiment !!! UPDATE - 01/02/08 03:25 AM

I don't think a lighter rotating assembly is going to save you any noticeable mpg. Acceleration will be better, but cruising, you are already spinning the rotating assembly. It sounds like you are building more or less how the 318s came from the factory in the 80s, w/ a tiny solid cam.
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! UPDATE - 01/02/08 05:22 AM

Quote:

I don't think a lighter rotating assembly is going to save you any noticeable mpg. Acceleration will be better, but cruising, you are already spinning the rotating assembly. It sounds like you are building more or less how the 318s came from the factory in the 80s, w/ a tiny solid cam.




The problem those cars had with intown miledge was gettin everything moveing, they got good miledge on the highway. The light weight stuff should help a bunch in town. I will be removeing at least 1600 grams from the rotateing assy plus removeing weight from the crank to balance it roughly 1200 more grams for a total of 2800 grams Now consider that weight in first gear has to accelerate 7.5 times as fast as the car it will be like removeing 21,000 grams from the vehicle, or almost 50 lbs everytime the engine speeds up or down. I also remember reading the weight actually goes up exponetialy not lineraly so it would rev even easier. And also my car is already 500lbs lighter than those dippys and 5th aves.

Compresion will be at least 1.5 higher ratio and should be good by itself for %4 more power from the same fuel or %4 more miledge. Also the tighter quench will cause a lot more turbulence resulting in a faster and more complete burn so I can run less advance to get les negative work on the piston before TDC. Even if the headers don't hit there tuned RPM the engine will do less work forcing the gasses through them than the 3 cats and very restrictive single exhaust the mid 80s cars had. I will have no EGR valve to slow the part throttle burn rate either.

The cam is a couple degrees smaller so a tad less overlap and solids have slightly less friction than a hydro mabey a tad more than a roller but I can tune the valve lash for a little more efficency.

If I can find a dual port intake it should also help build mixture velocity at low speeds around town.

I can run it a little leaner (14.7 is the goal)without worying about burning up the cats or NOx emmisions.

I am expecting to beat my current best MPG by at least 5 mpg while I am really hopeing for 10mpg better. My current best ever was 23mpg mostly highway driving. Strictly in town I would usually get 17mpg.

I think it should be a drastic improvement from the 80s
Posted By: dmerc

Re: Super duper gas miledge 273 experiment !!! UPDATE - 01/02/08 11:43 AM

I was getting 22mpg with my closed chamber 273 heads on a 318 and running a RV cam. It will be real interesting to see what you end up with. My engine was non quench with a 500 cfm carter carb and 2.92 gears, also lock up trany. I run at 5000 ft. Assuming the correct jetting I wonder what the effect of altitude is on gas mileage? Looking forward to your results
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPDATE - 01/25/08 05:36 AM

Fired it up today!!!

Here is what I have

68 318 block .030 over
KB 167 pistons .005 down
.039 felpros
Scat I beam rods
Balanced rotateing assy (very light)
273 2bbl solid cam, lifters and rockers
full grooved mains
302 casting heads with all sharp spots smoothed down
LD4b intake
850 thermo-quad
904 LU with low 1st and 2nd
2.76 gears
No PS No AC
Electric fan
TTI step headers
10 degrees at idle and 30 total and no vacume advance yet, I don't want it detonateing when I can't here it because of the exhaust.

and that is where it ends, no exhaust after the hearers. It revs real quick but it is sounding lean over 3500 rpm with a bunch of bucking and coughing. It hesitates if you hit it too hard also. I will try doing some carb tuneing tommorow. I may try to get an exhaust on it first though.

What size pipes should I run on this thing, any thoughts???

Any other sugestions???
Posted By: Rug_Trucker

Re: Super duper gas miledge 273/318 experiment !!! UPDATE - 01/25/08 06:09 AM

You had an adapter plate on it today when I looked at it?

If MPG is the goal H pipe as close to the collectors as possible. 2 1/4" - maybe 2 1/2?"

What is the specs for the valve lash? Set it cold tomorrow to the hot spec. If you get out there when it warms to 20*

Where did you set the cam?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPDATE - 01/25/08 02:45 PM

I do have an adapter on it, never got around to machining the manifold for the TQ.

I set all the valves to .010 when I built it just to get it going, I know that isn't quite right but wanted to get it going and didn't have time to look up the specs. I will find the specs today and re-do them.

The cam is in it's factory position. I could not find real good specs for it so I put it in how the factory would.
Posted By: Super6

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/25/08 04:37 PM

I'd be hesitant to put a header with a 3" collector on something that small. It will kill torque. For what you are attempting I'd either build a custom set of 1 1/2" primaries with 2 1/4" collectors or I'd go back to manifolds. That is way too much header for that engine. This is fuel economy err on the small side rather than the big side.
Posted By: AdamR

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/25/08 04:40 PM

How about a set of Spit Fire Tri-Y headers. I think they are 1-1/2" primary and a 2.25 or 2.5" collector,
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 12:24 AM

Low rpm tq is great, it is when it starts turning over 3000 that it just falls flat on its face

I put 2.25 duals with an H pipe on it today, no muffs yet.

The exhaust smells like exhaust from a new car

I pulled a couple plugs and they look better than when I put them in.
Posted By: AdamR

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 12:48 AM

May be pick up a LM1 to tune the carb with ?

I missed a few posts when I read it before. I dont see a problem with the TTI's. Maybe they are a little big but I wouldnt go and replace it.

I still think the LM1 is the way to go with tuning but I would also get a hold of Demon Sizzler and ask him for some TQ advice.

For mufflers I would add some straight throughs.
Posted By: Clair_Davis

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 02:31 AM

On my totally-stock 74 318, I installed TTI's step headers AND their 3" H-pipe duals. These goodies replaced my previous 2" duals w/o x-over, and 318 logs. Carb at the time was a cruddy TQ from an emissions 440 that ran pig-rich, and I can tell you there was NO loss in bottom end with the new way-oversized (by conventional wisdom) pipes. I think the benefits of the headers vs. mani's will far outweigh any potential loss due to oversized pipes. If I was building the 273, I'd either run a big fat single exhaust with a Flowmaster Y-pipe, OR duals using some long cone reducers from the headers down to like a 2.25" tubes and an X-pipe.

If you know how many HP you're working with, you can hit the Dynomax catalogs and find mufflers that provide unrestricted flow up to that number for singles or duals. Very helpful info.

Clair
Posted By: 71Chip

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 03:56 AM

Hey hotroddave how low do you figure the torque peak on that motor is?

I have found with my 5.0 mustang that if I can only go 65 mph, it actually gets worse mileage in 5th gear than in 4th. This is with a .69 overdrive I think and a 3.08 rear-end. You said you were considering installing an overdrive. The 518 is a similar ratio and you have 2.73s. If I am going 80mph the mileage picks back up in 5th gear, but I have found when I spin under 2k rpm at cruise, or especially under 1800 rpm, the mileage drops off.

Be interesting to see what you come up with.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 04:23 PM

The way I figure, the tq peak on the 273 motor the cam came from was 1600rpm. I have a few more cubes. I think relistically it should peak about the same but make a few more pounds when just running on the primaries. I do have headers and a 4bbl so it might make turn a little higher but not much and only when the secondaries are open (very rarely during cruising). Right now going 75 I am turning over 2500 so I don't think an OD will hurt me, it should drop me right around 1750. The headers are staying because this car is eventually destined for a 500hp 416 stroker after a few months of this experiment
Posted By: epaul

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 05:46 PM

Very good thread. You lean burn guys , would an MSD ignition setup help on getting a clean burn?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 06:04 PM

I think it would help, if I had a few bucks I would try one but I am jobless nad broke right now.

A couple other things I am going to try when I make a little more money is screens over the intake ports, an MSD, and an Offy dual port manifold.

I am really suprised how clean it smells, almost no odor at all! I am not takeing any chance and running it in a closed garage or anything.
Posted By: AdamR

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 06:16 PM

Quote:



A couple other things I am going to try when I make a little more money is screens over the intake ports, an MSD, and an Offy dual port manifold.





dont do it. If the screens come loose your in big trouble.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 08:49 PM

I have done it before with aluminum window screens and it did not cause a problem even when one of them did go through the engine I never knew it till I was swapping manifolds . If I do it on this motor I will use the gaskets that have the screens built in.
Posted By: aspenrt360

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/26/08 10:19 PM

i think the intake you are looking for is in the trade and swap section
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/27/08 12:38 AM

Well aparently somehow while the distributer was out of the car from the last engine to this engine the points gap was messed up. tightened the gap a ton to a .017 gap and now it pulls hard to 5000 with only the primaries hooked up
Posted By: HotRodDave

Re: Super duper gas miledge 273 experiment !!! - 01/27/08 01:07 AM

The intake in the trade section is a port-o-sonic, I am looking for a dual-port.

Thanks though.
Posted By: aspenrt360

Re: Super duper gas miledge 273 experiment !!! - 01/27/08 02:51 AM

sorry about that
Posted By: rbstroker

Re: Super duper gas miledge 273 experiment !!! - 01/27/08 02:00 PM

Speaking of intakes, I know that in order to use a later model intake on a '64-'65 273, the bolt holes need to be modified. Can anybody guide me through the process, step by step?
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/27/08 07:05 PM

My curiousity is piqued...how long till you have some mileage #'s...cause I get to add almost 30% to them! (The US gallon is 3.78L...the CDN/Imp gallon is 4.54L)

OH! And gas here is about $4.45/US gallon, and our dollars are near equal...
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/27/08 07:20 PM

Might be a while, the headers just burnt through the speedo cable and no money to replace it, if it ain't one thing it's another.

I think I will go out and reset the valve lash .010 intake and .020 exhaust, that is the factory 273 lash specs and I set them all at .010 when I put the motor together.

I am not super concerned about the miledge till I get everything sorted and the motor is broke in real good. In all my tinkering and peeling out and such it has not moved from the full mark yet
Posted By: shupe

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/27/08 11:16 PM

Interesting thread. I have a question about the optimal cruise rpm. What is the reasoning behind the peak torque rpm being the optimal cruise rpm?
Peak torque rpm is determined at full throttle. Cruise is done at fairly light throttle. Why would peak torque rpm be the optimal cruise MPG rpm - theory-wise?
-Shupe
Posted By: DaytonaTurbo

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/27/08 11:20 PM

You're running points on a car you're trying to get mileage from?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/30/08 04:35 AM

Been haveing some drivability problems, the nylon cam block on the points was disentigrateing and finally came off in the middle of a busy intersection in a torential down pour this morning. Put in new points in the mc-donalds parking lot and it has not run this good yet. In the search for the problem I tried a 600AVS and built a completly different thermoquad that I set up just for this motor. I was going to a budys shop that I knew was exactly 30 miles from my house. It was a level drive with mixed driving conditions. I filled up a block from his place and drove home in a constant down pour when the weather let up I went and filled up at the gas station 1/2 mile from my house and it only took 1.12 gallons to go 30.5 miles, or 27.2 mpg

I was hopeing for 25mpg hwy with it now so this even surpriesd me

I still have a few other things up my sleeve includeing an OD tranny, electronic ignition, vacume advance is not hooked up yet and I want to try the tourque-plus gaskets with screens. I need to get the speedo cable fixed so I can start makeing more of these MPG tests now to back things up.

As a reminder my previous best with the origninal bone stock 318 2bbl was 22 on strictly highway driveing.
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/30/08 06:12 AM

Dave, Dave, Dave...those points have GOT to go...especially considering the goal in mind here.

OK guys...I think Dave needs a Pertronix or an OE electronic ignition. Who's sending it to him?
Posted By: MarkZ

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/30/08 06:43 AM

Posted By: Clair_Davis

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/30/08 12:54 PM

That sounds like a great start, but checking mileage on such a short trip introduces all kinds of potential for error that can really influence the calculation. Getting 400 miles out of a tankful would be a better indicator of what's really going on. I track the mileage on my new Honda Fit, and I can see a difference when I fill up at a station where the car doesn't sit level like my usual station. It's enough to see 28 or 33 if I fill less than 1/4 tank, and I'm pretty sure it's all due to fitting more (or less) in the filler neck than normal.

Clair
Posted By: jcc

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/30/08 01:09 PM

.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/30/08 03:16 PM

For the lack of time and money I have in this I am very happy. I have an electronic distributer (several actually to get parts for recurving)and a wiring harness but no ECU yet.

I have just been cautious with the vacume advance as I don't want pinging on my hyper pistons. I will probably hook it up today.

I know things can be scewed by where I fill up. However I made sure every thing would be real close here, Both stations were level and unlike a fit or any other newer car there is no overflow tank or expansion tank in the cuda. When it is full it is full you can see every drop of fuel in the filler neck. Next time I get a few dollars I will get a new speedo cable and fill up and make a new check. The motor is still loosening up a bit too, it doesn't warm up near as fast as it was at first.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/30/08 11:51 PM

Adjusted the valves properly today and it (and a couple other things) really made the power jump up. a few intakes were loose a few were tight and of course all the exhausts were tight.

I realized since it had been sitting a few months the tires lost preasure from cold and just sitting I aired them up from 25 to 50 today. Tires say 51 lbs max.

I also bumped the timing up to 20 initial and 30 total and still no pinging

I bought and installed a speedo cable but it is not working

I also picked up an ECU so I have a complete ignition conversion kit to install next time I get some time.

Between airing up the tires, the valves and timing adjustments it really woke up today.

If I can ever get the speedo working I will get some more MPG numbers.
Posted By: 72challorange

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/31/08 12:22 AM

Use a portable GPS unit it will give you actual miles traveled and MPH as well.

Nice job on the project so far.

Tom
Posted By: aspenrt360

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/31/08 12:54 AM

is the speedo pinion indexed properly? just a thought
Posted By: OLD318

Re: Super duper gas miledge 273/318 experiment !!! UPD - 01/31/08 01:18 AM

If your trying to pull mileage out of a 318 2bbl
upgrade to electronic ignition or better still
a computer ignition system like MSD or Jacobs
(Jacobs mileage master comes to mind)...
rebuilt your front end, get steel belted radial tires and run them at max pressure...

I have a 318 B-Body and I have gotten before
(and still get) 15-16 city and 20-22 on the highway.... (hiway mileage is ONLY if I do the speed limit)above that (say doing 70-75) and I
won't break 20mpg at all!!!!)

In either case b-body or A-body your not going to do much better than that...

Remember (points aside)an A-Body 318 or B-Body 318 wieghts in the range of 3300+ pounds...
Posted By: HemiDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/01/08 04:02 AM



Just to make it more convenient to me....

Any updates?

Dave
Posted By: Mopar1

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/01/08 04:58 AM

My wife and I went to the Atlantic Nationals in Moncton, NB in July '06. We drove almost 2000 miles round trip and some site seeing. We averagerd 23.6 MPG. Not bad for a big car.

'68 Sport Fury vert.
318 2 bbl 727 auto
276 ratio
235/70/15 tires
2" dual exhaust
points ignition
Posted By: 375inStroke

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/01/08 09:47 AM

Quote:

Interesting thread. I have a question about the optimal cruise rpm. What is the reasoning behind the peak torque rpm being the optimal cruise rpm?
Peak torque rpm is determined at full throttle. Cruise is done at fairly light throttle. Why would peak torque rpm be the optimal cruise MPG rpm - theory-wise?
-Shupe



Peak torque occurs at the lowest brake specific fuel consumption, which is how much fuel you use per HP per hour. The engine makes the most torque at its most efficient RPM. Go above this RPM, and the engine will make more HP, but less torque, and it will be using more fuel to do it with less HP per unit of fuel.
Posted By: Clair_Davis

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/01/08 01:04 PM

But what's the BSFC for an engine at part throttle? I still haven't seen a good explanation of this aspect of engine/drivetrain design. My gut tells me it's not reasonable to say that because my 340 has it's peak torque at 4000, I should set my highway cruise at 4000rpm for best mileage. Somehow a 400hp Corvette can pull mid-high 20's on the highway while turning maybe 1500rpm. Torque peak on a Z06 sure isn't below 2Krpm. Until I can sort out how VE relates to a throttled situation, I'll stick to thinking that best economy is going to come at the lowest possible engine speed that you have good fuel control.


Clair
Posted By: Nick Mineau

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/01/08 01:37 PM

a engin will make peak torque @ say 4000 wide open put with less throttel opening mabe 10% throttel the torque curve moves down to say 1800 because theres not enoufgh air fuel to push it much higher. fo example drive in 1st gear at 2000 ad watch your peadel then 4000. it will take at least dubel the throttel to cruise @ 4000 because the rotating mass of the engine is limiting the rpms when you dont give it much fuel. wide open is another story
Posted By: DaytonaTurbo

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/01/08 03:48 PM

yeah, but since there is no way to measure where your peak torq is at part-throttle you're just guessing. Depending on the engine, IMO usually 1700-2000rpm is ideal for MPG. Much below that and your engine will really start to lug, especially if you hit a bit of wind. Much above that and you're revving higher than necessary.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/01/08 03:57 PM

If your cruising was done at wide open then yes you would get best MPG at peak tq. But really who cruises at full throttle? For best MPG you need to figure out where your part throttle peak tq is, I garauntee it will be lower than the full throttle pk tq. My car cruises about 2200 now and feels like it is way past a shift point, when I let off from steady cruising it vaccume brakes hard.

I did get the speedo working yesterday and filled it up again to get a fresh new reading. I have just been driving it around town so next fill up should be a good city miledge test but it will probably be a few days.

I will wait till I get those results before changing any more like installing electronic ign. or even hooking up the vaccume advance.

I think our 1/8th mile track opens in about a month and I will test it up there for the fun of it, any one want to make a guess on that? I will not change anything from the street tune.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/07/08 03:52 PM

I just filled up again, the rubbing block on these points are driving me nuts. This one fell apart and makes the car run like crap. I put another set in yesterday and checked my miledge (20 MPG city only and lots of cold starts and warm ups idleing and points screwing up). I wanted to try the vacume advance so I put in the shortest advancing can I had (10 degrees) and was going to go for a drive but as soon as I hit the gas the car would buck and cough violently and not move. As soon as I let off the gas it would idle perfectly. I jumped out and pulled it off and all was fine again. I tried adjusting the can to reduce when it cam on and didn't get any better, I guess it really don't want vacume advance at least not 20 degrees

If I get the time today I will put the electronic ign on. It has a 6.5 advance can on it so mabey that will work better. I was going to set up the curve useing the springs from my points dizzy and set the advance slot to the same length but the guts of the advance mechanisim are totally different in the mopar perf distributer so I will get it as close as I can.
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/09/08 12:13 AM

Posted By: Rug_Trucker

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/09/08 04:16 PM

All I know was it sure did sound sweet blastin away from the light in Bellview with the straight pipes!!

You scared that Mustang GT
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/11/08 03:42 PM

Just drove to memphis and broke it up into 4 parts.

100 miles at 65 I got 29 mpg twice.

100 miles at 75-80 I gon 25 mpg

the 4th 100 mile trip was cut short when a brand new U-joint broke

I did put on the electronic ignition before leaving and hooked up the vacume advance witch definately was helping. It was a lot easier to maintain a steady speed and was more responsive when I was cruising and needed to go up a hill. Idle smoothed out like glass with the electronic ign.

It does definately want another gear (OD)in the tranny, it is turning nearly 3000 at 80.
Posted By: JD340

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/11/08 07:03 PM

Wow! Those are some really good numbers! Maybe you should pass some of your knowledge on to Chrysler.While I might not understand all the theory and such behind your build, I sure can appreciate your results!
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/11/08 07:28 PM

too bad you're not made of money....I'd like to see comparisons with a small, fast ramp hydraulic (say a voodoo 60400) and the 273 solid in it, with both the 302 heads you're running and magnum heads....

it'd be interesting to see both mileage and performance numbers (be it RWHP/TQ or 1/4 mile times).....

I calculated your compression, assuming a 63cc head, 0 deck, 5cc valve reliefs and .039" gasket at about 9.6:1...what kind of gas does it run on? 87? 89? 92?


then it'd be interesting to see the same induction (heads, cams) comparisons on a 0 deck, flat top 360 short block, and what gas it would run on (it would be ~10.7:1 comp)
Posted By: 71Chip

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/11/08 08:06 PM


Anyone have numbers on what an electric water pump frees up?

Sounds like if you had the overdrive you would be in the 30s, or getting your current 65mph mileage at 80mph.
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/11/08 09:47 PM

Quote:


Anyone have numbers on what an electric water pump frees up?

Sounds like if you had the overdrive you would be in the 30s, or getting your current 65mph mileage at 80mph.




doubt it would be much...what you'd free up, you'd probably lose due to additional HP required to turn the alternator with the additional current draw. where you might see decent gains would be replacing a fixed fan with a thermostatically controlled electric fan, but the HP loss on that would be marginal compared to a thermostatically controlled clutch fan.

not necessarily--aerodynamic drag increases exponentially with speed, and usually becomes the driving factor in brake HP required to maintain speed above ~60mph, so even with OD dropping the revs down, it might not produce much MPG improvement at 80mph, since his revs aren't overly outrageous.
Posted By: dart4forte

Re: Super duper gas miledge 273 experiment !!! - 02/11/08 11:06 PM

Quote:

another thing to consider, I've read the closer the valve is to the cylinder side, the more swirl is induced from that shrouding. on a 273, anything larger than the stock 1.78/1.5 valves require bore notching to avoid a collision between the valve and cylinder bore, so the shrouding effects will probably be about the same regardless of head/valve size. on a 318's 3.91" bore, the magnum's 1.92/1.625" valves may give them an additional boost in induced swirl over a 273 head or '302 head with the small 1.78/1.5 valves...

I'm still not convinced the 273 will give any significant mileage improvement over a similarly built 318. for cost and ease of parts aquisition, I still think a 318 (roller cam block) is the way to go, especially if trying to optimize power and economy.




I run 1.84/1.56 SS Fererra valves on a .40 over TRW forged piston on my 273 and I have no shrouding and we didn't notch the block.
Flows 169 cfm from .350 through .500 inches of lift at a 116% port velocity

Same prep'd 318 swirlport flowed 158 cfm and started dropping at .400 of lift. It only had 114% port velocity.

Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 03:46 AM

I forgot to mention I did a comp test with it warmed up and all plugs reoved throttle open and it was 160-165 psi. I was expecting a bit more with that little cam and high comp. I might get brave and try some mopar thin composite gaskets. My pistons are .005 below deck so it would bring up comp, give a little tighter quench and reduce crevice volume. I have not tried anything but 93 octane, it says it has ethenol on the pump but I don't know the %.

As for the highway miledge dropping off, I had a couple hundred pounds of tools in the trunck raising the front a couple inches from static Also I do beleive bringing the rpms down will help the higher speed mpg. It is running almost twice where the tq peak should be. I really had to keep my foot in it to cruise at 80, the wind drag wasn't that bad because it would coast in neutral just fine, it is engine brakeing very hard and that leads me to beleive a taller gear would help. Also if WOT peak efficency is at tq peak than cruising part throttle peak efficency would be at some RPM point lower than that.

Patrick if money was no problem I really would have been running a 273 with custom flat top pistons, no valve releifs, a custom solid roller and some magnums with 1.88 valves and seat inserts and epoxy to funnel the Air fuel in. I would also be running a offy dual port intake and probably some custom headers to promote low rpm tq.

I found a new 195 t-stat in my cabinet so I may try that soon. I am running a 180 right now. I have an electric fan and never need to use it unless I am waiting in line at the bank

The w-pump is belt driven, I would expect a gain from an electric one but it would be very small and not worth the complication IMO.

As for teaching the OEMs something, they have to know everything I am doing, nothing fancy (yet)just applying common sense and fixing what they screwed up, heck I don't even have efi
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 06:23 AM

OK...I wasn't going to go here...but I gotta. If I was going to replicate this build, starting with a roller block, what kind of specs/numbers should I be looking at out of the cam???
Posted By: JD340

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 01:31 PM

Quote:

As for teaching the OEMs something, they have to know everything I am doing, nothing fancy (yet)just applying common sense and fixing what they screwed up, heck I don't even have efi




Maybe you could just REMIND them that it doesn't take 15 miles or wires, umpteen sensors+relays...to make an efficient vehicle. Now to make your experiment really interesting, go get it smogged! It would be interesting how that compares as well. Didn't CC build a 69 Camaro or something that sniffed as clean as a comparable late 80's model? Probably got it somewhere here in the archives!
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 01:46 PM

Dave, I hear ya, but I personally doubt the 45 fewer CID would have a super significant effect on economy, especially if you used a fast rate roller hydraulic in a roller teen block. you're probably fine with the .030-.033" quench the MP gaskets will provide, especially since I doubt this engine is/will be revved past 5k.

4speeds, if it were me, I'd slightly sacrafice mileage for power and use something like this cam, with mag heads, since they flow so much better than the 302's, and I doubt they'd have much hit in economy.

http://store.summitracing.com/partdetail.asp?part=LUN%2D60710&autoview=sku

if you were more economy minded, I'd go with something like this:
http://www.hughesengines.com/partDetail.asp?partID=11409&eTypeID=1
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 03:39 PM

Quote:

Didn't CC build a 69 Camaro or something that sniffed as clean as a comparable late 80's model? Probably got it somewhere here in the archives!




The emissions test here is only at idle and only HC and CO. It doesn't test for NOX or anything above idle. Also it is not required for a 68, one of the reasons I chose a 68, However if someone wants to cough up the $10 bucks I will try it.

This is the roller I would choose

http://store.summitracing.com/partdetail.asp?part=CRN%2D694105&autoview=sku
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 04:22 PM

I wouldn't choose that one because it specs out nearly identical to a factory roller cam, which you can usually pick up brand new for about 1/4 the cost of that crane one.....
Posted By: dmerc

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 06:06 PM

Great numbers Dave. I'm building a larger version of this engine (408) with magnum heads and an overdrive trany. With the kind of numbers you have achieved I'm sure I'll be in the 20's for mileage
Posted By: TC@HP2

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 06:52 PM

Now ditch that 904 for an aluminum OD four speed and break 30 mpg. Or maybe a 5 speed out of a Dakota.

Out of curiosity, do you know the lobe specs on that 273 cam?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 07:10 PM

I think with the OD I will gain some MPG at higher speeds, mabey another 2 mpg I am hopeing.

My theory on the 408 is with a .69 OD it will consume the same amount of air/fuel mix as a 281 inch motor set up like mine without OD so you might get a touch better MPG with a very mild 408 and an OD. My stroker that I will build when I get time and money will be a 416 and with mag heads and whatever I learn from this combo I should still get high 20s with the OD.

I just heard from the driveshaft shop and they said my shaft is trash and they want $230 to make me a new one. It might be sitting for a while
Posted By: dmerc

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 07:41 PM

Bummer about the driveshaft. If my 408 get 25 MPG I'll be I'll be driving that thing all the time!!
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 07:56 PM

If you drive it like it won't get 25 mpg

What's the rest of your build?
Posted By: dmerc

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 08:16 PM

Yeah, I know it won't do too well with my foot in it. Here is my set up. Roller block with .506 lift, 114 lobe seperation. Duration intake 216. Duration exhaust 224. M-1 Dual plane intake good for 0 to 5000RPM. 10.2 to 1 static compression using Wiesco 20cc dish pistons set to .005 above deck. Magnum heads cleaned up and intake bowls opened. I'm getting 155 PSI cranking compression with this combo at 5000 ft. I just put a 650 Holley carb on it and the response is great( on the run stand anyway). Still need to do alot of tuning once it's in the car but so far it's looking real good. Engine is internally balanced. I did use the cheap chinese cast crank and I beam rods but it all went together well.Hope it don't blow up!! Will be running a .70 overdrive trany. All this in a 71 Duster.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 08:32 PM

Between the Holley carb and big cam I think low 20s will be doing good. Holley carbs are bad on gas but yours is a little small so mabey it will be alright. The cam will make a nice compromise between HP and MPG. It has almost 30 degrees more duration than mine and that will knock off some of the super low rpm efficency.

I am guesing the tranny is a 833 od, that should help. .70 X 408 = 285 so not bad on the cruise prm VS displacement.

Are you running a 2.76 or similar gear?
Headers?
Posted By: dmerc

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 08:54 PM

I'll be running 3.23 gears. When I input all my data into the desktop dyno I get 380 Hp peak at 5000 rpm and Torque peaks at 3000 RPM... 500 ft lbs. Torque at 2000 rpm is 480 ft lbs. I'd say it's going to be a torque engine. I don't know if I input that right because the cam card has some negative numbers on it for valve timing. Cam was advertised as a 4x4 performance cam. Comp cams # 20-000-9 I'll still be real happy if this set up breaks 20MPG. That was my goal all along. And it should run good on pump gas too! Now I have to decide on the exhaust system I don't think there is much to gain with headers on this. What do you think? I have a set of 340 HP manifolds to use now.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/12/08 09:41 PM

Headers will help MPG and HP but unless you get some TTIs you will drag the exhaust on everything
Posted By: Rug_Trucker

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 01:35 AM

I thought MARTA here checked at 2500rpm and idle.
Posted By: GO_Fish

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 02:10 AM

Quote:

I'm sure I'll be in the 20's for mileage




That's a nice goal, but reality will probably hit you in the face.

I have to drive really gently to get 24 mpg out of my 300M with the 3.5 v6 and 4 speed auto trans driving mostly rural with a little city traffic mixed in. Not to mention the 300M has way better aero than any of our old cars.

The smaller/lighter '08 Avenger R/T with 3.5 v6 and 6 speed auto tranny is only EPA rated at 24 mpg highway.

So with 408 cubes and a 4 barrel in a brick, you'll be doing real well to crack 20 mpg at 60 mph.
Posted By: Jerry

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 03:29 AM

the reason the new cars get bad gas mileage is because the big three have to meet environmental requirements. if you retuned the newer cars then you could get much better gas mileage than before.

i would be eager to see what the emissions output is of this experiment. not that i'm a green weenie, but in reality you can't compare new cars to rebuilt cars that really have no requirements to meet. i wouldn't doubt that you could get an older car to get better gas mileage by tuning it really lean and sacrificing power and emission to get economy.
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 07:36 AM

Quote:

Didn't CC build a 69 Camaro or something that sniffed as clean as a comparable late 80's model? Probably got it somewhere here in the archives!




It was about 94 that article came out. It was carbed, ran 11's, IIRC, and sniffed to mid 80's V6 Buick standards. I talk about that one often, saying something like "It's not that it can't be done. It's that most of us are too lazy to try!"
Posted By: 375inStroke

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 08:35 AM

Quote:

But what's the BSFC for an engine at part throttle? I still haven't seen a good explanation of this aspect of engine/drivetrain design. My gut tells me it's not reasonable to say that because my 340 has it's peak torque at 4000, I should set my highway cruise at 4000rpm for best mileage. Somehow a 400hp Corvette can pull mid-high 20's on the highway while turning maybe 1500rpm. Torque peak on a Z06 sure isn't below 2Krpm. Until I can sort out how VE relates to a throttled situation, I'll stick to thinking that best economy is going to come at the lowest possible engine speed that you have good fuel control.


Clair



Lower RPM flows less fuel, yes, but if the engine happened to be at it's peak torque at the speed you were driving at, it would get better gas mileage. Lets say two similar cars were driving at 60 MPH and at the same RPM. One car was at it's torque peak and the other was under it. The one at it's torque peak would get better mileage. Now they both accelerate to 90 MPH. One car is above it's torque peak, and the other is at it's torque peak. The one at it's torque peak is now getting better mileage than the other car. We have much more to consider in reality than just BSFC and torque peak, but it is one of the many factors.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 02:14 PM

Quote:

Quote:

But what's the BSFC for an engine at part throttle? I still haven't seen a good explanation of this aspect of engine/drivetrain design. My gut tells me it's not reasonable to say that because my 340 has it's peak torque at 4000, I should set my highway cruise at 4000rpm for best mileage. Somehow a 400hp Corvette can pull mid-high 20's on the highway while turning maybe 1500rpm. Torque peak on a Z06 sure isn't below 2Krpm. Until I can sort out how VE relates to a throttled situation, I'll stick to thinking that best economy is going to come at the lowest possible engine speed that you have good fuel control.


Clair



Lower RPM flows less fuel, yes, but if the engine happened to be at it's peak torque at the speed you were driving at, it would get better gas mileage. Lets say two similar cars were driving at 60 MPH and at the same RPM. One car was at it's torque peak and the other was under it. The one at it's torque peak would get better mileage. Now they both accelerate to 90 MPH. One car is above it's torque peak, and the other is at it's torque peak. The one at it's torque peak is now getting better mileage than the other car. We have much more to consider in reality than just BSFC and torque peak, but it is one of the many factors.




I sort of agree, if it was at the tq peak of whatever throttle angle you were running. Like was mentioned earlier in the thread, How was full throttle tq peak have anything to do with part throttle cruise If you were to dyno the engine at 1/2 throttle and find a tq peak I think you would be a lot closer to the "ideal" cruis RPM.

Also for the guy with the 3.5 300m. That car is a lot heavier than mine for one. For two it has to meet emisions standards, noise standards, ease of mass production, bean counters. The 300m could get a ton better miledge if they put any effort in it, look at the LS powered camaros, I rode with a guy and even with goofin off a little it got 29 mpg on the highway at 75.
Posted By: BigTerry

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 02:35 PM

I readed a story in mopar mag 3 or 4 years ago that explain that when your engine reach certain vaccum reading that engine would have reach it sweet spot for fuel economy! is this true?
Posted By: TC@HP2

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 02:44 PM

What are the specs for that 273 2bbl cam?
Posted By: Clair_Davis

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 03:08 PM

Bingo. If peak torque at WOT was the only thing that mattered - and that's almost always the only throttle position it's measured at - just dropping down a gear or two should improve mileage, right? We could all be driving PowerFlite 2-speeds or manual 3-speeds with 2.93 cogs. Again, I don't have any documents to back me up, but I think a lot more fuel is used with every turn of the crank than there is by changing the BSFC some small percentage. With all else being equal, an engine will use 50% more fuel at 4500rpm than it will at 3000rpm.

I think one thing that's killing mileage on many new cars is that they're big, fat, heavy, pigs chock-full-o creature comforts that Average Joe thinks he needs because some corporate marketing wonk told him he did. Take out some of the cruddy worthless "features" of new cars and they'd get a lot lighter. Reducing unsprung weight, like giant, heavy bLiNg rImZ , will make any vehicle perform better instantly in almost every respect, including mileage.

Another thing that hurts new cars is that they pretty much HAVE to stick to 14.7:1 AFR to keep the catalytic converters happy for a long time. Steady-state highway cruising really can tolerate much leaner mixtures, but converters don't work well there, and I think it's NOX emissions that go up when it's lean. If you can tune your carb to pull 16-17:1 at high-vacuum cruise, you can really bump mileage up. GM did this in the late-80's & early-90's EFI systems, but had to disable the code for emissions reasons. The code is still in the GM computers, so I'm planning on enabling that feature when I get my tune better. Going from 14.7 to a conservative 16:1 is an 8.8% improvement right there. If you're getting 15mpg, now you're at 16.3mpg. If you're getting 25, now you're getting 27.2. That's a noticible improvement. Going to 17:1 is a 15.6% improvement...

Oh, and before I forget, that's dang good mileage for that little car so far. I can't wait to see how it does once the carb and ignition are better sorted out.

Clair
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 03:17 PM

Not to mention when that 'teen loosens up a little...
Posted By: JD340

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 03:36 PM

Here a question. In the "big scheme" of things; which is better? Better MPG, or less emmisions? Honestly, using less fuel/ mile has got to be a positive thing, right?
Posted By: dezduster

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/13/08 04:17 PM

MILEAGE possibly the most sophisticated topic moparts could tackle. I had a 318 2bbl in a 84 dodge with 3.23 gears and 35 inch all terrain tires. In this state of tune it got really bad mileage city and highway. Swapped to 4.11 gears and the mileage was greatly improved, RPMs are not the only or even the most important factor for mileage. My Duster with 4.30 gears and 28 inch tall tires, 727 and a 340 would get 14 15 on a road trip to Fallon 150 mile round trip. While I was there made 2 passes at the drag strip. Same Duster 422 ci small block 3.23 gears 28 inch tires 5 speed OD 1800 RPM at 70, 20 to 21 MPG if I am law abiding. The 340 didnt mind the RPMs the stroker really wants to be put to work. The things that I am certain about is run as much VACUME advance as possible with out detonation. Keep tires inflated as as per tire manufacturers suggestion and drive gently. This is an INTERESTING thread keep up the good work peeps.
Posted By: volaredon

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/14/08 10:10 PM

Yeah but if you're getting 20+MPG from a 318, its basically USING all its fuel rather than spewing unburnt fuel out, meaning that to be doing that well on MPG, it HAS to be burning clean at the same time! My 76 Charger SE with 2.76 gears would get 25 MPG if I kept it on cruise at 62-63 MPH. Yet it seemed by seat of pants to have a "sweet spot" right at 70, and it still got like 21ish on cruise at that speed. But I guess that aerodynamics started to play a part at the higher speed (the car was a "brick") Heck my 87 B 250 van with the 318-2 bbl and the lean burn intact would also get over 20 MPG on the cruise at 62ish; 2.94 gears there, 235 75R 15 Michelins.
Posted By: GO_Fish

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/15/08 02:03 AM

Quote:

Also for the guy with the 3.5 300m. That car is a lot heavier than mine for one. For two it has to meet emisions standards, noise standards, ease of mass production, bean counters. The 300m could get a ton better miledge if they put any effort in it, look at the LS powered camaros, I rode with a guy and even with goofin off a little it got 29 mpg on the highway at 75.




Dave, I wasn't refering to your build, I was referring to DMERC's 408 stroker.

However, the 3.5 in my 300m has 10:1 compression (just throwing that out there), and it's curb weight is 3577 lbs. The curb weight for the Avenger R/T with the 3.5 is 3355 lbs. And both average 24 mpg highway. They can get more or less at any given moment depending on the situation. How much does your car weigh in at?

Per the Moparts archives, 67-71 A engined A bodies weigh 3000- 3200 lbs. Do you feel that weight saves that much more gas than aerodynamics?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/15/08 03:35 AM

Asumeing he builds a 408 stroker with a .70 overdrive. That motor if built to the same compression A/F ratio cam ect... It could potentially use less fuel than my motor is useing right now. It will only be makeing %70 of the strokes as mine at cruise. .70 X 408 = 285.6 cubic inches displaced every drive shaft rotation where mine displaces 323 cubic inches every driveshaft revolution. The only thing is he is going to build compromises into his combo that are different from mine for the sake of performance. His heads are bigger and will flow at a lower velocity than mine are flowing now. His cam will be more duration and overlap that will hurt efficency, he is also going to a lower gear ratio. I don't think his combo will get as good as mine is getting but if he keeps from he may not do to bad like low 20s.

As for the weight thing I think it makes more differance in town. My car the day I bought it we weighed it with a full tank of fuel and it weighed 3060. Since then I have added a 8.75 rear but removed weight via aluminum intake lighter Neon buckets and a mini starter from the front as well as lightening up the rotateing assy a few pounds. I think it is probably around 3100 pounds with a full tank now. It is also sitting a little lower to the ground now. I do think areo is part of the reason for the big drop from 65 to 75 mph. but not all of it.

The 300M can not run as lean as my motor because a lean mix will over heat the cat and make the NOX emmisions go up. I set my carb up with the smallest jets and biggest rods I could find and lowered the metering tree till it started to lean miss and then brought it back up a hair so I know it is cruising on the ragged edge of lean right now.

It is funny that the problems I expected to have are not being problems at all. No burnt valves no pinging it still makes good hp whenever I want it Just some stupid periphrial junk
Posted By: dmerc

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/15/08 01:20 PM

Hey Dave I just did a check on the 408 Roller cam and come up with 8 degrees of valve overlap. How does that compare with your cam? Also I compared my Magnum heads to some 302's and they looked very similar to me in terms of runner size.(Although I may be confusing the 302's with my 273 heads) I'm hoping that 408 cubes trying to breathe through the little ports I should have very good port velocities. Of course I won't know until I get this heap running. It's all bench racing at this stage

Oops!! I goofed, the overlap on my cam is 41 degrees. Not 8. I used the .050 duration figures and was supposed to use the advertised number
Posted By: TC@HP2

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/15/08 07:04 PM

Quote:

How does that compare with your cam?




Yes, what are the specs on that 273 cam?
Posted By: dmerc

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/15/08 08:34 PM

Here is something interesting. A stock 340 4 speed cam (268/276) had 44 degrees of overlap. My roller cam has 41 degrees of overlap instead of 8. I used the wrong duration numbers to figure it. So this explains why I get 155 psi cranking compression with a 10.2 to 1 calculated compression ratio. Dave is right I'll be giving up some gas mileage, but hopefully not too much.I'll just have to drive faster to get the engine in it's efficiency range. Then the air drag will kill me Still it should give at least 20 MPG
Posted By: 360view

Re: Super duper gas miledge 273/318 experiment !!! UPD - 02/18/08 12:38 PM

http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

then read

http://www.prime-mover.org/Engines/GArticles/bsfc.html

somewhere i read a link about a company in Florida that runs classes for gasoline engine private airplane owners about how to set cruise at the 200 degrees F past the lean side of peak EGT in order to get to best BSFC...but I can't find the link in my bookmarks

someone ought to dig out this article and post it online:

http://www.sae.org/servlets/productDetail?PROD_TYP=PAPER&PROD_CD=933033

because I seem to remember it had a bsfc graph that would tell us the typical behavior of a Magnum engine like cylinder, but I am not certain of what is actually in the article because I looked at it so long ago
Posted By: toyotajeep

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/01/08 06:56 PM

It has been a few weeks, has their been anymore data collected?

I am very interested in this since I currently am building a car and deciding which path to take.

Thanks, ROB
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/01/08 07:47 PM

Haven't been driving it much lately. Last tank was strictly city driving, lots of cold starts and warming up, stop and go sort of thing and it got 19. That is the only tank since I broke a U-joint, where we also idled on the side of the road for probably an hour or more on that tank also. I figured it was a tainted test so didn't bother to post it.

I did try 87 octane this last time I filled up and it pings just a tad at higher rpm on full throttle blasts. I could probably retard the timing a couple degrees to fix it but it is not bad and I don't drive it at full throttle much so I am not concerned with it.

After this I would like to try the thin mopar head gaskets, I still think there is a little more MPG by switching to them. I might even try the screens over the ports when I do that.

I haven't had time to tinker with it lately though. I bought 74 a dart race car project and I am trying to put it together to sell.

After I get a little money from that project I still want to put in an A-500... that should help me on the highway to break 30mpg.
Posted By: autoxcuda

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/01/08 08:41 PM

Quote:


Per the Moparts archives, 67-71 A engined A bodies weigh 3000- 3200 lbs. Do you feel that weight saves that much more gas than aerodynamics?




Those numbers are out of the MP books. They are all light on reality.

My 68 Cuda coupe
340 auto
11.75 disk conversion
aluminum intake
non A/C car
steel rims
1/2 tank gas
lighter weight modern bucket seats
aluminum master
after market steering wheel (pick up a rallye steering wheel sometime!)

All that was 3340 on a cert. grain elevator scale.
Posted By: toyotajeep

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/01/08 10:54 PM

I had a bonestock, 100% stock, 1973 318 Duster that got around 16, and that was mainly hwy. Almost all hwy in fact. It was a bit disheartening.

I have really enjoyed the build and am contemplating something similar with one of my early A's.

Thanks for the update.

ROB
Posted By: goldduster318

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/02/08 04:40 PM

Quote:

I had a bonestock, 100% stock, 1973 318 Duster that got around 16, and that was mainly hwy. Almost all hwy in fact. It was a bit disheartening.

I have really enjoyed the build and am contemplating something similar with one of my early A's.

Thanks for the update.

ROB




mine got 13.5 when it was stock...should get BETTER mileage now with a hot 360
Posted By: toyotajeep

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/02/08 05:49 PM

I would think that my single exhaust etc. weren't helping my situation. It was a one owner, and the guy told me that it got maybe 18 at best when new.

I was not real excited when I saw that 16 MPG. I was thinking that some headers and a mild cam etc. I could do that good.

It ran so well that I didn't have the heart to screw it up so I sold it. Should have kept it.

ROB
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/13/08 04:52 AM

I just wanted to throw out an update on a couple things.

1. It has been warming up around here a little and it started pinging a little on heavy accel so I topped off the tank with about 5 gals of 93 and that made it quit. It had a mix of 89 and 87 in it. I think I will be useing 93 from here on out.

2. I have only driven strictly in town with this last half tank and it got 19 again.

I finally hooked up a vacume gauge to watch when driving and it's kinda interesting. I can keep the vaccume at 20 inches cruising at 70 on a flat road with no wind. It only pulls 25 idleing in park. I though it would be a little higher idleing and lower cruising. This still leads me to beleive it would love an OD gear. I bet in town it could go over 20 and I could easily knock down 30+ on the highway especially if it was a 5-spd manual OD
Posted By: 74chargr

Re: Super duper gas miledge 273 experiment !!! - 03/13/08 07:25 AM

I got 23mpg with my /6 duster. That was with a a833od and the high geared rear with an automatic (i converted the auto to a manual). The car is in car heaven now . Still have all the parts for the convesion.
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/13/08 12:29 PM

Quote:

I just wanted to throw out an update on a couple things.

1. It has been warming up around here a little and it started pinging a little on heavy accel so I topped off the tank with about 5 gals of 93 and that made it quit. It had a mix of 89 and 87 in it. I think I will be useing 93 from here on out.




hmm...ever thought of adding a water injection system?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/13/08 02:25 PM

I thought about water injection but figured it would be a pain to keep up with and install compared to the mabey 1 mpg it would give me if that.

It is cheaper to operate now than before.

Conservitivly, under the same driving conditions I am getting 5 or more mpg better in town or highway so...

27 / 3.45 = about 12.7777 cents per mile

VS

22 / 3.25 = about 14.7727 cents per mile

On a 15 gallon fill-up I save about $9.58 over what it would have been before. Plus it makes a nice chunk of extra hp over the old motor so I don't mind the premium

On top of that I save a couple bucks on soda and candy bars because I fill up less often
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 03/16/08 05:27 AM

Dave- Did I miss it? I can't recall seeing if you got a weight on that thing yet, as driven...
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 03/16/08 01:56 PM

Quote:

Dave- Did I miss it? I can't recall seeing if you got a weight on that thing yet, as driven...




He could have drove over the scale at the "Flying J" when he was at my house last week. It is the shortest way home from here
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 03/16/08 07:04 PM

Have not got an exact weight, I am guessing around 3200 now. It was 3060 and I added an 8.75 and disc brakes but also put on a mini starter and aluminum intake as well as no mufflers at all now.
Posted By: Idunno

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/17/08 06:18 AM

I am going to install a 68 273 in my 1950 Dodge pick up. I have a 67 Formula S 4 barrel intake. Would that be a good one to run with the mild cam and Electronic ignition. I am shooting for mileage too.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/17/08 01:14 PM

That would be a good intake. If you were going to run a thermoquad you would need an adapter though.
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 01:49 AM

OK...I am losing sleep at night, and this is part of the reason. I have a 64 Valiant Signet. I am debating a mimic of sorts on Dave's idea here. I have 2 318's to choose from...one Mag and one 302 headed roller from the late 80's. Dave utilised the 273 solid cam. Will it hurt this project to run a roller? And if not, what kind of specs (duration, LSA, lift) should I be looking for? Target CR with quench? Will the benefit of a few less pounds also help? I can go wherever I want with this in some ways...and am seriously thinking that I will go 4-speed. 833 with 2.7-2.9's, or 833OD with 3.2-3.5's? Or chuck it all and do the same thing with a \6? I keep thinking that the theory of light recip assembly gets blown out the window with the 225, as that crank with it's 4.25" stroke ain't light, and it gets tougher to get a cam with specific specs, and exhaust becomes more costly to make it work efficiently (1 of Dutra's manifolds is the same price as Harold's Spitfires...) as well as carb/induction limitations. Just thinking out loud and looking for a bit of feedback before I start into it...

Thanks.
Posted By: Grassosgarage

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 02:39 AM

I built a 318 basically the same w/ KB 167s and 302 heads but I ran the pistons .002 out of the hole with .039 gakets. I ran it on a stand and it's really crispy. The cam is Comp 256XE. I am putting it in a 65 Valiant with stock manifolds, dual exhaust, 833 OD, and a 8-1/4 wih 3.21 gears. I have a few issues with the clutch, but hope to have it together by the summer. Am hoping for 25+ mpg on the highway too. This is a great thread. More real world results please!
Posted By: Rug_Trucker

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 10:22 AM

Quote:

as that crank with it's 4.25" stroke ain't light, and it gets tougher to get a cam with specific specs, Erson is doing a slant group buy (1 of Dutra's manifolds is the same price as Harold's Spitfires... don't hold your breath waiting for Harold

Thanks.




Build a 318 IMO.........
Posted By: BigTerry

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 10:43 AM

the one thing that been eaten at me was the concept that fi was suppose to give better performance and fuel mileage over a carb what gives?? I would love to get alittle more fuel mileage out of my 99 p/u 318 auto. What about installing taller tires wouldn't that help fuel mileage?
Posted By: 74chargr

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 11:40 AM

I personally think the slant six is better for mpg than the 318. But you sacrifice the power in exchange for mileage. To get the best of both worlds I would turbocharge the slant. Slants are tough and realiable. The long stroke is good for gas mileage. The power produced is in the low end. Tune it to this and you will get excellent mileage. The turbo is there when you want oomphhh. People have told me 30 mpg is not unheard of in a a body with a slant. Thats stock! So if you start off with a winnner its only going to get better from there. I think the only way to get power and MPG is with a small engine tuned for MPG with a turbo. Two extra cylinders are just going to need more gas to keep it turning.
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 01:12 PM

Quote:

OK...I am losing sleep at night, and this is part of the reason. I have a 64 Valiant Signet. I am debating a mimic of sorts on Dave's idea here. I have 2 318's to choose from...one Mag and one 302 headed roller from the late 80's. Dave utilised the 273 solid cam. Will it hurt this project to run a roller? And if not, what kind of specs (duration, LSA, lift) should I be looking for? Target CR with quench? Will the benefit of a few less pounds also help? I can go wherever I want with this in some ways...and am seriously thinking that I will go 4-speed. 833 with 2.7-2.9's, or 833OD with 3.2-3.5's? Or chuck it all and do the same thing with a \6? I keep thinking that the theory of light recip assembly gets blown out the window with the 225, as that crank with it's 4.25" stroke ain't light, and it gets tougher to get a cam with specific specs, and exhaust becomes more costly to make it work efficiently (1 of Dutra's manifolds is the same price as Harold's Spitfires...) as well as carb/induction limitations. Just thinking out loud and looking for a bit of feedback before I start into it...

Thanks.




I'd shoot for as much static CR as tolerable (depending on fuel grade) while shooting for a tight quench. I'd use the mag 318, personally. KB167's for pistons, stock rods. the 167's spec out at a 9.588" deck height, I think I'd square deck the block to 0 deck or maybe to ~.008 under, (if I kept them below, I'd use the MP .028" gasket, might net you an extra .1 compression. I'd use the mag heads w/a good valve job, maybe get them milled to clean them up a skoash. I'd play with some of the dynamic compression calculators and shoot for a cam that yields ~8.5-8.8:1 DCR.

cam choice, I'd look for as much lift for as short a duration as possible, probably a wider LSA for less overlap (and it'll help the engine pull higher in the rev range and not poop out at 4000 RPM)...I'd look at something like the hughes HER9204AL or the comp 254HR, & run the GM 3100 springs/retainers.

for tranny/driveline, I'd run an A833OD, 25" or so tall tires and a 2.94 rear.

I'd guess you'd get significantly more power than stock and better economy.
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 01:30 PM

another thought...

mill the snot out of the heads to get a very high comp ratio and cyl pressure (11:1-12:1) and use water injection to control detonation...I've got an article from Mother Earth News from '79 where a guy did this on a ford festiva...he had the motor running a 12.7:1 comp ratio and was averaging 50 MPG CITY (easily a 15-20 mpg city increase), while passing all NOx emission standards for the time....
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 02:14 PM

I would use the 273 before the slant because parts are way easier to get, only need custom pistons. The slant is pretty much imposible to get good quench and because of that it will not tolerate as much compression. If you really want to go 6cyl get a 3.9 mag V6, you could use the same pistons I did and use the factory heads that are really just like 302s and after 92 they were magnums.

As for what mpg the new mags get it is a joke. They need more quench, KB 167 or 107s depending on 318 or 360 are needed. That will raise comp and quench. A good fuel injector would be bound to help, the factory ones squirt out a stream right on the side of the pushrod bump that washes a nice clean path across the bottom of the port and never gets atomized. A switch to some accels with the cone type spray pattern should help fix that. A more complete burn will make the O2s rear rich so the computer will compensate by leaning it out a little. I bet those changes ther would make a very noticable differance in mpg and probably even help hp and throttle response

Also for the gaskets the mopar gasket will raise the compression on my motor 1/2 point. Not only is it thinner, it has a much smaller bore size. I think if I can get the money and time I will swap them. The reduced bore size should help mpg by eliminateing a big dead area that doesn't really push on the piston.

I would like to get a custom speced cam but that is even more money.

I agree with patrick that the mag head would be better, but only slightly.

Remember it is not just one area like light rotateing assembly that helps the mpg, it is the whole package. Quench, compression, lighter rotateing parts, high gears, tiny duration/overlap cam, very lean, 190 t-stat, electric fan, lowered car, low rolling resistance tires.

I would like to try this combo but about 12.5 compression on e-85. Should make for a real good cost to miles ratio. I bet a high comp 273 on e-85 would make as much power and mpg as my 318

Someone asked about useing a roller cam, I think it would be hard to get custom lobes that small, the 318 2bbl cam from the mid to late 80s would probably be the best readily available roller cam. Just changing that should not hurt much and may even help a tad. I don't think the factory 318 2bbl cam would be a bad choice, I just wanted to be able to play with the lash a little and I already had it sitting here.

I just saw on good morning america some concept cars that got 100 mpg, there is some big 10million prize being given out in 2010 for the best one so I need to get out there and get to work on the cuda
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 02:24 PM

One more thing on the magnums.

It would be really cool if someone with some good fab skills would take and put the injectors (accel cone spray petter ones) all on one rail inside the beer barrel pointing each one directly at the entrance of the port. This would give more time for the fuel to vaporize before going in the chamber. That is one reason EFI in general don't get better mpg.

I know all these things I talk about are not worth much all by there selves but when you get a whole bunch of things working together you can see some big saveings.
Posted By: Jerry

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 03:18 PM

Quote:

would be really cool if someone with some good fab skills would take and put the injectors (accel cone spray petter ones) all on one rail inside the beer barrel pointing each one directly at the entrance of the port. This would give more time for the fuel to vaporize before going in the chamber. That is one reason EFI in general don't get better mpg.




This makes no sense. the injector itself atomizes the fuel. injecting at the top of the port can lead to fuel droplets falling out of suspension. at high flow volumes injecting at the port entrance would be good as the charge velocity would be high, but for idleing it would be awful.
Posted By: RestoRick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 03:40 PM

This is interesting... Hughes Modified Magnum Intake
Scroll down and read the mileage increase claims..

Rick
Posted By: MarkZ

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 04:25 PM

Quote:

another thought...

mill the snot out of the heads to get a very high comp ratio and cyl pressure (11:1-12:1) and use water injection to control detonation...I've got an article from Mother Earth News from '79 where a guy did this on a ford festiva...he had the motor running a 12.7:1 comp ratio and was averaging 50 MPG CITY (easily a 15-20 mpg city increase), while passing all NOx emission standards for the time....




That sounds really interesting. Got a digital copy of that article?
Posted By: BigTerry

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 05:46 PM

the link won't work at work, is it the intake that suppose to use all of the stock parts from the orig intake? I'm really interest in that intake result.. Have anyone use that intake and what kind of result did you get?
Posted By: Supercuda

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 09:55 PM

hmm, 25 mpg.

My 87 Diplomat would get that with it's lockup trans an 2.94 rear gear. But in town mileage was lame. Stock 87 318 in it, well almost stock. Deleted lean burn and installed the MP ignition and an Edlebrock 1406 carb.

When I swapped in the 360 the highway mileage dropped some, to about 20-21, but the power....
Posted By: Grassosgarage

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 10:12 PM

87 Diplomat is the same core package with 302 heads on a 318, but with barely 8:1 compression, choked down exhaust, and a lot more weight than my little 65 a-body. Diplomat has lock-up, but my Valiant has OD so that should equal out. I don't think 25 mpg is out of the question for my combo. I agree with a lot of the other guys that weight makes a big difference on avg mpg especially in city driving.
Posted By: Supercuda

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 10:16 PM

The cop spec 318 in an 87 Diplomat was a lower compression ratio than the 2bbl version, I believe it was "blueprinted" at 8.1:1 vice the 9.0:1, which in real life usually means about .2-.3 lower than blueprint.

Point is, your goal should be very attainable. City mileage should be much better with the lower first gear of an OD A833. You probably already have hte Diplomat beat in weight, too. Funny thing is I sold that Diplomat and it's 318 is going into my 65 Cuda, one day.
Posted By: Grassosgarage

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 10:24 PM

I think maybe the 4bbl cop-motor also had the larger chamber 360 heads (308 casting?) which caused the lower compression.
What do you guys think of asking for an "economy" forum on Moparts where we could share results on different combos and ideas to save on actual driving costs for our daily drivers? Even with all the OD products available, I don't think many of us are trying to squeeze mpg out of our big block beasts, but more of us are trying to build fun drivers that are on par with newer cars mileage wise. This is new territory for a lot of us hot rodders, and sharing info is good!
Posted By: GO_Fish

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 10:26 PM

weight AND idleing make a big difference. My commute to work is 3/4 rural and 1/4 in town with a couple red lights and stop signs. My 300M has the instantaneous and trip MPG computer. On the rural part of my ride I can get 30 MPG driving gently, but add 2 or 3 traffic signals to the mix and the overall MPG drops to 24. Put another way, for each traffic light, you have to drive 5 or 10 miles open road for your MPG to recover. At short traffic lights, (with an auto), shift to neutral, this mocks a stick shift. RPM's will pick up slightly, but the engine vacumn picks up also because the engine is not laboring against the torque convertor. For long lights, kill the engine and restart.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/20/08 11:27 PM

Quote:

Quote:

would be really cool if someone with some good fab skills would take and put the injectors (accel cone spray petter ones) all on one rail inside the beer barrel pointing each one directly at the entrance of the port. This would give more time for the fuel to vaporize before going in the chamber. That is one reason EFI in general don't get better mpg.




This makes no sense. the injector itself atomizes the fuel. injecting at the top of the port can lead to fuel droplets falling out of suspension. at high flow volumes injecting at the port entrance would be good as the charge velocity would be high, but for idleing it would be awful.




Take apart a magnum motor with about 200,000 miles and look in the port and tell me the injector atomizes the fuel. The port is almost always clogged with deposits except a little clean valley through the crud where the fuel runs down the port in a steady stream, never becomeing ariborn. Ever wonder why the comparble chevys and fords always got better miledge? Also why would injecting the fuel at the entrance of the port hurt idle so bad? My carb idles smooth as glass and the fuel is introduced before the entrance to the port. The high vaccume helps vaporize the fuel at idle keeping it in suspension pretty good.

In response to the guy saying to throw the car in neutral at a stop, everyone take cover People seem to be pretty strong on either side of the fence on this one. I just turn the idle so low it almost makes no differance if your in gear or not, shows about 1 inch differance from neutral to drive. If you are makeing less vacume it will pull less fuel into the engine at idle. Coasting in neutral will help to but some guys disagree about that also, more

We may never get our own forum but ther is a nice thread in the archives
Posted By: GO_Fish

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/21/08 12:38 AM

let it

my thoughts ( )... with an auto in gear and stopped... The engine has no idea the car is not moving (speaking of non computerized cars). It is still fighting the brakes trying to move the car. We all know how an auto creeps forward at idle when it is in gear without the brakes!

Definitely better to go to neutral for long downhills. If you stay in gear, the rear gears will cause engine braking, and that means you loose forward momentum (numberically higher rear gears, may as well hit the brakes). Not what you need unless you need to stop.
Posted By: Rug_Trucker

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/21/08 02:56 AM

Quote:

This is interesting... Hughes Modified Magnum Intake
Scroll down and read the mileage increase claims..

Rick




Linky no worky
Posted By: FuryUs

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/21/08 10:22 AM

Quote:

Quote:

This is interesting... Hughes Modified Magnum Intake
Scroll down and read the mileage increase claims..

Rick




Linky no worky



Go to http://www.hughesengines.com/ then magnum engine, induction. It's a little pricey...
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/21/08 12:03 PM

Quote:

I think maybe the 4bbl cop-motor also had the larger chamber 360 heads (308 casting?) which caused the lower compression.
What do you guys think of asking for an "economy" forum on Moparts where we could share results on different combos and ideas to save on actual driving costs for our daily drivers? Even with all the OD products available, I don't think many of us are trying to squeeze mpg out of our big block beasts, but more of us are trying to build fun drivers that are on par with newer cars mileage wise. This is new territory for a lot of us hot rodders, and sharing info is good!




my 5th ave, with a stock roller motor and 2.24 gears w/lockup 904 would pull 22-25 on the highway, 13-15 in town, typically 18-20 combined, and that's a 3800 lb car.

cop 318's have the same pistons as 2bbl 318's but large chamber 360 heads, that's where the compression drop comes in. they aren't 308's, but the precursor to them....

I don't think we need a separate forum, just start threads in the general Q&A (:

supercuda, are you the artist formerly known as Thunderstruck?
Posted By: RestoRick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/21/08 02:19 PM

Quote:

Quote:

Quote:

This is interesting... Hughes Modified Magnum Intake
Scroll down and read the mileage increase claims..

Rick




Linky no worky



Go to http://www.hughesengines.com/ then magnum engine, induction. It's a little pricey...




Linky worky for me...

Here's what they're competing against...($600ish)
If it does what they say it does it might be worth it to some...
Mopar Performance MPI manifold
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/24/08 11:59 PM

Quote:

...but the engine vacumn picks up also because the engine is not laboring against the torque convertor. For long lights, kill the engine and restart.




I just press the clutch...

And correct me if I'm wrong, but was there EVER and OD auto from Ma Mopar that did NOT have a lock-up converter?

And lastly, if MPG is the greatest concern (I can't believe I'm asking this...I'm almost scared of the answer) what takes less power to turn? A 904 based auto or an 833?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/25/08 02:28 AM

Some 518s did not have lock up.

A 4spd will be more efficent but the wife won't let me because she might need to drive it someday
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/25/08 02:37 AM

Time for a new wife, by the sounds of things. This one isn't willing to learn anything new...

I was asking for my benefit anyways, as I looked at my 64 on Sunday, and oughta be dragging her home soon...

Quote:

I would like to get a custom speced cam but that is even more money.




And what kind of specs would you be looking for, Dave???
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/25/08 11:36 AM

Quote:

Quote:

...but the engine vacumn picks up also because the engine is not laboring against the torque convertor. For long lights, kill the engine and restart.




I just press the clutch...

And correct me if I'm wrong, but was there EVER and OD auto from Ma Mopar that did NOT have a lock-up converter?

And lastly, if MPG is the greatest concern (I can't believe I'm asking this...I'm almost scared of the answer) what takes less power to turn? A 904 based auto or an 833?




'91-92 A518's were non-lockup. all A500's were lockup, and all newer 518/46RH/46RE are lockup.
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/25/08 02:21 PM

I think for a custom cam I would want about 175@.050 with as much lift as they can possibly get from a .904 diameter lifter and get a 110 or mabey even 112 LSA to keep overlap next to none. Imagine a baby comp MM lobe. Remember that at short durations the flat tappet can lift the valves faster than a roller. I would probably try to get as high of a rocker ratio as I could to get lift open real good so it could make a little bit of hp. The extra hp would be there if needed but not costing you anything when you don't need it. I think the overlap and late closeing intake are the 2 biggest things for desighning an MPG cam. The overlap costs efficency when some of the intake charge goes out the exhaust (obviously wasted and produces no power)and some of the exhaust goes in the intake track(reversion)and dilutes the next charge comeing back in causing it to burn slower. If you look at some of the newer engines they are going this direction and still makeing real nice hp. An example is the new Hemis with right around 200 degrees duration. Also of less importance but still there is the ex opening point, the charge is still burning when it opens so opening it a couple degrees later gives it a couple more degrees to push on the crank.

I think with heads really desighned to get flowing at low lifts like magnums with 33 degree seats and deshrouded chambers around the 2.02 valves you would be suprised at the hp it could make also. It would not be a beast so to speak but it would be way better than a Geo metro 3cyl for sure.

I think a combo like that could even lower the tq in the rpm range even more and alow for a higher gear ratio also.

BTW according to the waller calculator I had the cuda doing 139 mph the other day
Posted By: FuryUs

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/27/08 08:18 PM

Quote:

BTW according to the waller calculator I had the cuda doing 139 mph the other day



What does this mean?
Posted By: HotRodDave

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/27/08 11:05 PM

I put the RPM the tire hight and gear ratio into the speed calculator and it said I was going that fast when I was "not-raceing" a saturn aura XR the other day. I only looked at the tach not the speedo until I had slowed down a bunch, so when I got home I checked to see how fast it was.
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/30/08 08:26 AM

Wow...did you really mean 175ş @ .050"? Looking at Comps lobes this is about all that stands out...Lobe# 3100 230ş adv. 178ş @ .050.

.405" w/1.5's, .432" w 1.6's, and .459" w/1.7's. I'd prefer to see the 1.6 or 1.7 number with 1.5's, I think, but this was about the only lobe they have with less than 200ş @ .050. Most are 230+...

http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=20-416-3

How does this look for an "off-the-shelf" flat tappet unit?
Posted By: FuryUs

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/30/08 12:06 PM

Quote:

I put the RPM the tire hight and gear ratio into the speed calculator and it said I was going that fast when I was "not-raceing" a saturn aura XR the other day. I only looked at the tach not the speedo until I had slowed down a bunch, so when I got home I checked to see how fast it was.



Gotcha! Good thing you weren't racing--that might waste gas!
Posted By: FuryUs

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/30/08 12:11 PM

Quote:

the one thing that been eaten at me was the concept that fi was suppose to give better performance and fuel mileage over a carb what gives?? I would love to get alittle more fuel mileage out of my 99 p/u 318 auto. What about installing taller tires wouldn't that help fuel mileage?



The problem is peak fuel efficiency isn't always the cleanest burn. The tailpipe has to put out limited amounts of... whatever comes out the tail pipe, and leaning it out for best mileage can jack that up. Also, it seems to me that the pre-magnum TBI motors got better mileage, but the lean condition led to cracked heads over time.
Taller tires should help with cruise mileage if the combo is right, but it'll affect acceleration. Skinnier tires will help with rolling resistance.
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/30/08 12:34 PM

Quote:

Quote:

the one thing that been eaten at me was the concept that fi was suppose to give better performance and fuel mileage over a carb what gives?? I would love to get alittle more fuel mileage out of my 99 p/u 318 auto. What about installing taller tires wouldn't that help fuel mileage?



The problem is peak fuel efficiency isn't always the cleanest burn. The tailpipe has to put out limited amounts of... whatever comes out the tail pipe, and leaning it out for best mileage can jack that up. Also, it seems to me that the pre-magnum TBI motors got better mileage, but the lean condition led to cracked heads over time.
Taller tires should help with cruise mileage if the combo is right, but it'll affect acceleration. Skinnier tires will help with rolling resistance.




tuning for emissions (specifically lower NOx emissions) leads to fuel economy compromises

taller tires might be a wash, because if they have worse rolling resistance, or if they raise the truck up higher, and cause more aerodynamic drag, you'll need slightly more power to maintain the same speed, offsetting dropping the engine RPM.

also, look at the HP/tq ratings of a magnum 318 (230 hp/300 tq) vs. say the 318 out of my 5th ave that got 22-25 highway mpg (140hp, 265 tq)....more power requires more fuel....
Posted By: patrick

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/30/08 12:46 PM

Quote:

Wow...did you really mean 175ş @ .050"? Looking at Comps lobes this is about all that stands out...Lobe# 3100 230ş adv. 178ş @ .050.

.405" w/1.5's, .432" w 1.6's, and .459" w/1.7's. I'd prefer to see the 1.6 or 1.7 number with 1.5's, I think, but this was about the only lobe they have with less than 200ş @ .050. Most are 230+...

http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=20-416-3

How does this look for an "off-the-shelf" flat tappet unit?




too much overlap...that has 45 degrees overlap. I'd look at a voodoo 60400 (250/256, 208/213@.50, .454 lift, 112 LSA. that has only 29 degrees overlap (compared to about 16 degrees for a stock flat tappet 318, or ~26 degrees for a stock flat tappet 360 cam)....
Posted By: 4speeds4me

Re: Super duper gas miledge 273/318 experiment !!! UPD - 03/30/08 07:17 PM

So, if I could get that cam on a 116ş LSA, what would it do to my overlap? Most of the times when I'm doing this stuff, I'll find a cam that has a close spec. Then I get a look at my available lobes from my cam regrinder, and tell him what lobe and LSA I'd like. He finds a core that'll take it, and 75-100 bucks later I have a cam ready to go to my specs.
Posted By: Dakota_Don

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 03/30/08 11:05 PM

so what are the specs of this 318 thats gets good gas MPG?
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 03/31/08 03:09 AM

Off the top of my head? 30 over 318 with KB167 pistons. 273/2-bbl solid cam. 302 casting heads with stock valve diameters and the sharp edges smoothed off. Factory 4bbl intake with TQ, IIRC, and TTI headers because the next plan is a 400+ inch SB. Best numbers he's posted so far if memory serves are 23 city and 29 HWY...maybe 23 combination city/hwy, and 29 hwy...
Posted By: patrick

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 03/31/08 12:02 PM

easiest way to determine overlap:

take the adv. intake and exhaust duration. add them.

take the sum, divide by 4.

subtract the LSA from that

multiply by 2.

for example, a comp XE250H is 250/260 adv. 206/212@.050, on a 110 LSA.

so 250+260=510. 510/4=127.5 127.5-110=17.5 17.5*2=35, the cam has 35 degrees of overlap. widen the LSA to 116, and you get 127.5-116=11.5 11.5*2=23, so the cam would have 23 degrees of overlap.

BTW, the overlap numbers I was quoting for the stock cams I was assuming a 114 LSA, since I could find advertised durations for them, but not LSA, and 114 seems reasonable...
Posted By: Dakota_Don

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 03/31/08 11:08 PM

23 and 29, with a 318...... for real

so what if i took a 68 318, added magnum stock heads..

decent exh manifold (360 or headers) and some HYD camshaft and good Ignition system with an OD trans then it should get that or close to it..
what intake? cast iron w/ a mid 70s BBD 2 barrel or alu w/ a TQ 4 barrel?
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/04/08 11:00 PM

Some of you need to go back and read the entire thread, many of the questions being asked have been asked and answered a couple times.

4speeds has it right on, except I have a brand new LD4b intake. I also have a 190 tstat and electric fan a LU 904 tranny with low 1st and 2nd gears. 2.76 gears. Manual steering no ac no power brakes. Light weight aftermarket scat I beam rods. Electronic ign. I get about 5 mpg better now than the when I bought it with the bone stock #s match 318 2bbl. I have to use premium gas but it is still cheaper to operate than before with a nice bonus of more HP and TQ derived from burning more of the fuel when it counts, in the engine not the exhaust.

I think the mag heads would be about the same mpg with a little more WOT HP.
Posted By: QuickDodge

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/06/08 02:57 AM

How does one tune for maximum mileage? I saw on a previous page that Hotroddave40 used the smallest jets and largest metering rods he could find. I have a different carb, so this advice may or may not work.

I've heard in the past that an excessively lean mixture will burn hotter, possibly causing overheating and/or burnt valves. So my question is, How can one know when the engine is tuned as lean as possible without doing any damage to the engine? Ideally, I'd like to know how to reach this point without using an oxygen sensor to measure the air/fuel ratio.
Posted By: Jerry

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/06/08 11:38 AM

there is no way to do that. without accurate reading of what your doing its just a crap shoot. also tuning every engine is slightly different, so what works for one won't generally work for another when trying to run the most power , the best fuel efficiency, etc. getting an average state of tune you can use the same settings as you'll be close. what carb do you have?
Posted By: dmerc

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/06/08 12:18 PM

And sometimes running as lean as possible does not yield the best gas mileage. I have richened the the jets in some carbs and have actually increased my gas mileage
Posted By: QuickDodge

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/06/08 06:07 PM

I have a Mopar Q-jet. The carb and intake came off an 80's non-computer controlled pick-up truck. I'm guessing the basic procedure for tuning for max mileage would be similar with other carbs also.(obviously the details would differ though)

Seems like I read years ago that the lean burn system Mopar used in the 1970's leaned the mixture out to a 16:1 or 17:1 ratio of air to gas. Is this approximately as lean a mixture which can be used and still maintian drivability? If drivability is acceptable, does this mean the mixture is not lean enough to harm the engine?
Posted By: dmerc

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/06/08 09:35 PM

For what it's worth, I just did a valve job on a 79 Volare with lean burn. It had 2 cylinders with no compression. Took it apart and two exhaust valves looked like they had a cutting torch taken to them. When will a super lean condition cause driveability problems? Depends on alot of things!
I think alot of the cracked head problems are due to running the engines on the ragged edge of driveability
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/06/08 10:22 PM

I think the main problem running lean is for high HP motors. The lower power motors will take longer to be affected by a lean condition, less overall heat. I also think by getting a really good homogenius mixture will allow you to run leaner with less problems because you eliminate hot spots during combustion, or at least reduce them. I left the exhaust valve rotators on this motor to help keep them more even tempertures. The area between the seats is where these heads like to crack so I polished that area to reduce stress risers and hot spots there. I have a list of stuff I would like to do to it still but I am broke and I think I have snatched up the simplest improvements, everything else is going to be like pulling hens teeth, cept mabey the OD trans.

A friend is offering to pay my way to the Chrysler classic in BG for my 30th bday so I might get to run in the 1/4 and see how fast it is. I am torn bout them lettin the brand Xrs in though.
Posted By: dmerc

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/07/08 12:56 PM

I did the same thing on my magnum heads. I don't know why they leave that sharp edge between the valves. I filed mine down nice and round. I don't think I'll have any problems with cracking.
Posted By: QuickDodge

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/07/08 03:55 PM

Would installing valves made from a more heat resistant material help to reduce the chance of burning the valves by running a lean mixture? Seems like a logical solution, but what kind of valve(s) would be more heat resistant?
Posted By: QuickDodge

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/09/08 03:27 PM

Hotroddave40, do you mind telling us some more details about your ignition system. I know you posted earlier that it is an electronic ignition system. Can you give us some details on the advance curve? What do you have the base timing set at? (since changing to electronic ignition) Are you running a factory coil and spark plug gaps?
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/09/08 08:03 PM

I have a chrome accel coil. Mopar electronic ign dist and harness with a autozone box. The distributer is the new adjustable mallory one. I set the idle for the most vacume then drove it with the vacume unhooked and adjusted the mechanica, it didn't need much taken out from factory, till it quit knocking at any throttle. Then I hooked up the vacume advance and did the same thing, drive adjust drive adjust till the knocking just went away. I would have to check again but I think the initial ended up about 16btdc and the total mechanical was around 32 btdc.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/19/08 11:14 PM

Just had it weighed at bowling green,

#3077 and it had a full tank of gas.

BTW the miledge seems to be pretty consistant 17 in town if I am real hard on it and 29 on the highway if I am real easy, like a steady 65mph. Most of my tanks are mixed driving and get about 25. If I am real easy on it in town it will still get around 20-21

I can't seem to get over 30 with it though
Posted By: dmerc

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/19/08 11:24 PM

I wonder what a set of Magnum heads with dished pistons and quench would do? I'd bet money you'd be over 30 then!
Posted By: patrick

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/20/08 06:26 PM

no, for mileage you want efficiency, which means lots of cylinder pressure, so you want as high of compression as possible with as little overlap....if you wanted to really boost mileage, I'd use mag or 302 heads milled down to about 55cc w/flat tops, run a short duration cam like dave is, and water inject it (like a lot of turbo guys do) for detonation resistance.
Posted By: FuryUs

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 04/20/08 06:31 PM

Slow to 60 mph for a tank.
Posted By: Anonymous

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/21/08 04:43 AM

If I might chime in for a second....

There are a few factors you need to take a long hard look at.

#1 is your ignition timing as it relates to burning efficiency. If you map out piston velocity relative to crankshaft position you'll see a sine wave pattern. In order to make the most power and waste the least fuel you want all of your fuel to burn as quickly as possible when the piston has the most mechanical advantage. But you can't let the chamber exceed a particular temperature or you'll have auto-ignition (knocking).

If you're at 16 degrees BEFORE TOP DEAD CENTER that means you're starting the burn way way in advance of it's maximum mechanical advantage. This indicates either (A) Your fuel is not ideal for your goal -OR- (B) Your combustion process is slow and inefficient. There's not much you can do about A but B you can change.

#2 EGT (Exhaust Gas Temperature) Again relating to efficiency of burn. Whereas previously we're seeking maximum use of our mechanical force, EGT dictates maximum use of your CHEMICAL "force".

When the fuel burns and does what it does, heat is generated. Heat is energy. Wasted energy is wasted fuel. A VERY HOT EGT INDICATES ENERGY WASTED. A hot EGT is also caused by a lean mixture. Lean out the mixture and the EGT goes up. Makes no sense?

That's because the burn cycle is taking longer than the duration of the power stroke. You're wasting power by dumping it out the exhaust. Again, shorten the burn time.



Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/21/08 09:21 AM

One of my grandfather's favorite sayings was:

"Every job is easy if you have the right Tools"

to really do what you want to do
you need
EGT,
wide band oxygen sensor
at minimum
and in the ideal case.....
a set of eight spark plugs with fast reading pressure sensors embedded in them

Before using stock cast Magnum heads on a high compression and lean air-fuel engine set-up I would "temper" them in an non-oxidizing atmosphere oven at 520 degrees F for 24 hours, and then polish over the sharp edges in the combustion chamber.
Posted By: CrAlt

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/27/08 03:11 AM

Any new numbers from this 318?

Im looking to start a project like this but with a 170cui slantsix or a 273
Posted By: bboogieart

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/27/08 03:24 AM

Quote:

Would installing valves made from a more heat resistant material help to reduce the chance of burning the valves by running a lean mixture? Seems like a logical solution, but what kind of valve(s) would be more heat resistant?




aluminum pistons will melt before your valves will. burnt valves are usually due to an exhaust leak.That is why they look like they have been cut with a torch. Basically that is what happens. when oxygen is introduced to the exhaust charge.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/27/08 07:06 PM

I have been driving it a lot and it always falls right in range with previous postings. Tennessee has started putting %10 ethenol in all the gas but it didn't seem to make any differance. As a matter of fact I topped it off with 5 gallons of E-85 the other day to fill the tank, didn't seem to affect the way it drives any I will post how it affects the MPG when I finish off that tank. It was about 50 cents cheaper than 93 octane and Tn does not subsidize it. I would not be afraid to run another point or 2 compression with it to bring back some of the suposed eficiency loss

I would recomend the 273 over the slant because the only custom thing you need is pistons. With the slant you need a ton of milling to get closed chambers and zero deck. If you did all that milling I bet you would still need a custom piston to get valve clearance and low enough compression unless you want to make it run on e-85. If you could go this way though I bet a 170 would get better mpg on e-85 than a 273 on 93 octane. However if you threw an a-500 behind the 273 it might be close. I do beleive based on what I have learned: a 273 built with custom pistons and custom cam and a performer intake and OD that 35 mpg is reasonable. Also if I was running a motor that small that slow I would get some smaller headers like 1-5/8 and mabey add in an extra 12 inches to the primaries to boost low rpm tq. A narrower wheel would probably be good also, mine are 7.5 wide but have a very low profile tire to lower rolling resistance.

If I built it for e-85 I would open the heat crosover to gain some bit of efficency that it suposedly loses. It burns cooler so it should still not ping. Mine is blocked and I think it would knock if I opened it.

I mention all the e-85 stuff because I am thinking of switching it over with thinner head gaskets and some head milling.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/27/08 07:23 PM

Quote:

One of my grandfather's favorite sayings was:

"Every job is easy if you have the right Tools"

to really do what you want to do
you need
EGT,
wide band oxygen sensor
at minimum
and in the ideal case.....
a set of eight spark plugs with fast reading pressure sensors embedded in them

Before using stock cast Magnum heads on a high compression and lean air-fuel engine set-up I would "temper" them in an non-oxidizing atmosphere oven at 520 degrees F for 24 hours, and then polish over the sharp edges in the combustion chamber.




BTW If any one wants to donate any of this equiptment I would love to have a chance to use it but I am broke. Also if someone wants to donate some part or another for me to try I will try them and give some real world feedback but remember I have no more money right now to spend on it. I have got some emails about stuff but I am not able to spend bottemless dollars on this. I will say it would not be this far with out some help from my friends, you guys, and my local mopar machine shop.

Posted By: CrAlt

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 03:49 AM

Wow so much info out there...

My goal is to SAVE money so $$custom$$ parts are out. Anything I do is going to be done with off the shelf parts.

Also running on 87 is a must. The higher grades jump 10 or 15 cents between the grades here.

Im leaning more to the 170. Mainly because I already have 1, 2, and 4bbl intakes to play with and 2 diff sets of headers. As well as a ported, milled head with the MP oversized valves.

My plan so far is to put the better head on my original 225 thats in the car with a supersix (carter BBD) intake/exst manifold and run 2.25" exst.

Drop the front of the car to match the sagging rear springs

Clutch fan (already have)

Multi-spark MSD box. (already have)
And some type of belly pan to blend the front bumper to under the K-member. There is kinda a big gap there and it looks like the K-member is just hooking the air.


I'll keep my goal low at 25highway. I already get 18-22 with the messed up 225 thats in there. Since i already have most of this crap kicking around i'll see how it works out. If it goes well ill spend the money on doing up a(still looking for one) 170short block.
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 04:05 AM

I think this is a time when I'd go for the cubes within the family you have parts for. I think the 55 cubes of the 225 wouldn't hurt the mileage by any means, and the couple extra ponies would be welcome. That's my thought on the subject, at least...
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 01:16 PM

Time to get out the triagular file and groove the flat quench areas on the 302's. Polish the chambers

Gasket match the intakes and leave the intake manifold alone so you have a slant anti-reversion effect.

Gasket match the exhaust on the top and sides of the exhaust ports. Not the floors!

My 302's are almost to that point. Just no money for the valve job, and I need toput a new seat put in. where I got too crazy with the die grinder.
Posted By: Super6

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 05:46 PM

I think the only areas left where we would see gains at this point are expensive. Cheapness is out of the equation. He has hit his 90% and the last 10% are going to be have to be fought for.

The areas I think that could still be improved are

- converter efficiency, high dollar transmission rebuild
- spark control, possibly Jacobs set for economy
- electric fuel pump, cooler fuel at the bowl.
- weight reduction
- build specific headers.
- roller cam
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 06:55 PM

with some yarn,
a hot glue gun,
and a 'chase car' with movie camera
I would bet that
some simple aero 'tweaks' could get the
Highway MPG up at little cost:

http://autospeed.com/cms/A_108656/article.html

the above is the first of a 5 part series from the 'Land of Oz'

This archived website allows you to find out your aero and tire rolling resistance with coast down test on flat pavement:

http://web.archive.org/web/2004080307322...tDownCalcs.html

But I personally like to coast down a 4 to 6 percent grade hill, then use the 'top out' speed on the hill and the equations in this article to find the Cd and rolling resistance:

http://www.etrucker.com/content/downloads/ccj0302.pdf
Posted By: CrAlt

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 07:56 PM

Quote:

with some yarn,
a hot glue gun,
and a 'chase car' with movie camera
I would bet that
some simple aero 'tweaks' could get the
Highway MPG up at little cost:

http://autospeed.com/cms/A_108656/article.html

the above is the first of a 5 part series from the 'Land of Oz'

This archived website allows you to find out your aero and tire rolling resistance with coast down test on flat pavement:

http://web.archive.org/web/2004080307322...tDownCalcs.html

But I personally like to coast down a 4 to 6 percent grade hill, then use the 'top out' speed on the hill and the equations in this article to find the Cd and rolling resistance:

http://www.etrucker.com/content/downloads/ccj0302.pdf




Good links.
Posted By: MattW

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 10:55 PM

I have been following this post and I give it a . I was reading somewhere that somebody did a test way back in 1950-1960 can't remember. For every 100 percent of fuel and air that enters a combustion chamber only 28 percent is used for power the rest is out the tail pipe. They retested again in 1990 and found out that it was raised to 30 - 32, WOW Now that's progress They also mentioned that the finer the mist ( more atomization) you can get your fuel mixture the more complete burn. There have been many attempts at this Singh groves, running your fuel through hollow exhaust seats with variable valve timing. Or just heating your fuel. ( I believe Patton had a Mechanic that tried this on his Tank fleet).
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/28/08 11:37 PM

I would not try to heat the fuel before it goes in the carb, ever heard of vapor lock?

Mabey if you had EFI you could wrap a heating coil around the fuel rail

The only big gain I think I have left is the OD trans. It should be at laest an easy 2 or 3 mpg.

Other than the trans; things like EFI, custom headers, custom cam, skinneyer wheels, weight reduction... might get me another 2 or 3 all together. Mabey for another $10,000 I could get closer to 40mpg so I can save $2 - 3 grand..
Posted By: CrAlt

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 02:19 AM

Well it was pouring rain here so i didnt get much done on the slant.

I put in a vacuum gauge and a tech... FYI: Sunpro tach's are CRAP. Says im idling at 250rpm (yes its set for 6cyl).. On the upper RPM's its at least 150rpm off.

Anyways...

Bumped the timing to about 17 at idle and 51 btdc total. All in by 2100ish. Was 7/41BTDC.

Im going on a 260mile each way trip this weekend comming up so i'll see what happens.
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 04:54 AM

Tell you what Dave I'll finish my 302's and get the valves done and mildly shaved. This is after the Duster leaves the driveway with the 4 speed.

I'll give you back your Stromberg that you lent me. Then you can try it.

We can see how my heads with the RUG _ TRUCKER MPG, low to mid torque work. CC them then test them. Then cut them with grooves retest them and see if that treatment will change things.

IIRC I need to finish 2 exhaust ports.
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 05:11 AM

When we going to do a Moparts Nashville time trial night or day?
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 11:13 AM

There is also a Stant 'Standard Grade' 205 degree thermostat that should give about 1% MPG boost if a VERY careful test is done.

Stainless steel wire mesh across the ports between two intake gaskets will 'probably' reduce fuel droplet size and slightly improve fuel economy.

Rigging up an exhaust gas recirculation system feeding into the air inlet might be good for 5% better MPG at highway speed, but the idle quality will suffer unless a way is available to turn it off below 1500 rpm.

I would not personally be afraid to try the new Mobil One Synthetic OW-20 oil, but only if the rings are in good shape.
Posted By: MattW

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 12:24 PM

Heating the fuel was after the carb. I believe they used a heating element underneath it. Anyway the other article that I remember was in Hot Rod. They were talking about this guy who had a 327 Chev with hollowed out exhaust seat. The fuel would flow through there and get super heated. There was small pin holes in the exhaust seat that when the valve open would jet out fuel. To make this work he needed variable valve timing. The longer the valve stayed open the more RPM. At the end he had 450 hp and using 70% of the fuel more efficiently= more MPG. He also had less emmisions
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 06:45 PM

Volcin fuel injection. It was in HotRod in the mid 90's. Excellent article...
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 08:36 PM

another aero drag article just published by AutoSpeed in Oz

http://autospeed.com/cms/A_110351/article.html
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/29/08 09:43 PM

From the pages of Design News

http://www.designnews.com/article/CA6551496.html?industryid=43655

Thirty-Year Quest for Lean Burn

Michael A.V. Ward, Ph.D., President & Board Chairman, Combustion Electromagnetics Inc. -- 4/28/2008

Lean-burn technology is alive and well and can help the auto industry — if we let it. With lean burn used to its full extent, today's vehicles can improve fuel economy by 30 percent, identical to that of the direct-injection diesel. It could help us deal with government mandates on fuel economy — well before 2020.

It hasn't been that way for 25 years, since Chrysler and Honda first attempted lean burn in 1975. They achieved a lean air-fuel ratio (AFR) of 20:1 for better fuel economy, versus the normal 14.7:1 AFR. But, they were unable to burn lean enough to meet the EPA's standards for NOx.

Two other companies, Nissan and Ford, introduced the NAPS-Z and the PROCO around 1980, with two spark plugs per cylinder. They performed even better under dilute AFR conditions. They used exhaust gas recirculation (EGR) for very low NOx and obtained 60 percent of the gain in efficiency available with lean burn. Lean burn at light loads reduces pumping losses, heat transfer losses and increases Otto cycle efficiency. Despite their good results, both approaches were abandoned.

The three-way catalyst operates in a narrow range of 14.7:1 AFR, with oxidation of HC occurring above 15:1 and reduction of NOx occurring below 14.5:1. Under lean conditions, the catalyst cannot reduce NOx emissions. NOx peaks at 17:1 and falls off with leanness. An AFR of 25:1 is needed to satisfy EPA emission standards.

In 1977, CEI was formed to pursue lean burn. Initially, it pursued ignition aspects of lean burn and had its first success in 1986 on a Ford Escort at Lucas, England. Under conditions of 20, 35 and 50 percent load, it obtained 25, 17 and 10 percent gain in fuel efficiency at 24:1, 24:1 and 28:1 AFR, with negligible NOx — never seen before in a homogeneous charge engine, reported in the “Economist,” July 5,1986.

In 1987, CEI was invited to GM where it ignited mixtures five AFRs leaner. In 1989, flow tunnel tests were conducted, but CEI was not shown the results. GM went no further despite the positive results.

Successful lean burn tests were also conducted at Mazda, but further ignition development was needed, especially in the one-coil-per-plug format.

Between 1990 and 1995, carmakers gave up on lean burn. California dictated the super-ultra-low emission standards to, in effect, kill lean burn and increase our dependence on imported oil.

Five years later, CEI finally received the flow-tunnel from GM. The results were astonishing. GM's HEI had a lean limit of 23:1 to 26:1 AFR. The CEI ignition gave, by comparison, 33:1 to 34:1 AFR, or a hard-to-believe eight AFRs gain. Flow enhanced lean burn, contradicting Exxon's claim. Flow-coupling was seen to be the missing link in lean-burn technology.

Chrysler tested the CEI ignition on a four-cylinder engine and found it to be “an enabling technology for the lean-burn engines of the future.” Three years later, CEI built a single-cylinder engine with two plugs and strong flow-coupling. The ignition was developed to deliver five times the energy with small coils. The engine results were, again, hard to believe. An air-fuel ratio was achieved above 30:1, never seen before, with an efficiency of the direct-injection diesel. Lean burn had been solved. See “Lean Burn Lives.”

This year, a low-cost, high-efficiency, high-compression ratio lean-burn engine, similar to the May Fireball, was designed with a more than 40 percent gain in efficiency, with the promise of being the “Engine of the Future.”

Author Information
Michael A.V. Ward is the founder of CEI in Arlington, MA. He can be reached at ignition@rcn.com

© 2008, Reed Business Information, a division of Reed Elsevier Inc. All Rights Reserved.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/30/08 02:07 AM

Interesting stuff 360 veiw.

It seems as though I could run a lot leaner with a super high out put ign(and asumeing a real thorough mixture). I picked up a MSD 5200 box at bowling green, are they any good? Can I open the plug gap more with that than the mopar electronic ign I have on it? How big of a gap have you guys gone before problems?
Posted By: CrAlt

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/30/08 03:21 AM

Quote:

MSD 5 Ignition, PN 5200
The MSD 5 is our entry level multiple spark ignition control. This inductive discharge ignition is designed to be used on stock vehicles with no performance upgrades such as a cam, intake manifold, or carburetor.
Below 3,000 rpm, the MSD produces a series of sparks instead of just one. This ensures that the fuel is burned completely which in turn provides more power, smooth idle, quick starts and overall driveability improvements.
The MSD 5's powerful sparks are just the ticket to enhance the power of your foreign or domestic car's ignition output. The MSD 5 can be triggered using points or the electronic amplifier on late model vehicles.

NOTE: Not for use with magnetic pickup distributors or distributorless systems. Not recommended for General Motors HEI ignition systems





Only sounds useful if you still have points.
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/30/08 11:56 AM

I am not a fan of the MSD ignition muliti-spark system.

I did install one on a Subaru boxer 4 cylinder years and found no difference except much more radio interference.

I do still have a MSD ignition delay 'add-on' box that allows continued use of the oem ignition but allows up to 20 degrees of ignition retard. I bought this MSD single spark 'black box' after finding that the Mopar Performance PCM computer for a 1995 Magnum 5.9V8 advanced the ignition timing so much that it would ping when at full throttle starting at 3200 rpm in 95 degree summer air temperatures even if Sunoco 95 octane gasoline were used.

If you want to try lean burn carb jetting,
I would suggest using Iridium alloy 'tiny tip' sparkplugs with wide gaps.

The Pertronix 'Second Strike' aftermarket ignition would be a better choice than the MSD, because the first strike is still the long burn time from the inductive coil.

Tiny 'vortex generators' in the intake manifold port ends might be a low cost mod that would help during lean afr





note that these vortex generators,
called 'Wheeler VG design'
are actually two airplane wings side by side
with each wing at the angle
that causes a vortex
similar to what you see on the Space Shuttle



Mitsubishi has this paper in pdf file form that shows two other shapes that can be used as vortex generators
that I call 'shark fin and 'Kamm-back' shapes:

http://www.mitsubishi-motors.com/corporate/about_us/technology/review/e/pdf/2004/16E_03.pdf

Mitsu research resulted in single wing vortex generators on the Lancer:

http://www.seriouswheels.com/2005/2005-M...ar-1280x960.htm

You can see similar single wing vortex generators on the top of some BMW outside rear view mirrors, and on the bottom of the Mercedes ML500 SUV outside mirrors
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 04/30/08 05:05 PM

Quote:

There is also a Stant 'Standard Grade' 205 degree thermostat that should give about 1% MPG boost if a VERY careful test is done.

Stainless steel wire mesh across the ports between two intake gaskets will 'probably' reduce fuel droplet size and slightly improve fuel economy.

Rigging up an exhaust gas recirculation system feeding into the air inlet might be good for 5% better MPG at highway speed, but the idle quality will suffer unless a way is available to turn it off below 1500 rpm.

I would not personally be afraid to try the new Mobil One Synthetic OW-20 oil, but only if the rings are in good shape.




Do you know the part number for the 205* t-stat?
Will it fit the early style big water neck?
Posted By: CrAlt

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/05/08 03:08 AM

Why would that do anything in a carbed car?
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/05/08 10:32 AM

I still have that Stant 205 degree thermostat,
but unfortunately it is in a garage
about 1100 miles away right now.



I found the Stant 205 degree F by looking in the Stant part number book in a Napa store back in 1999.

With so many cars running 203 degree F thermostats now (2004+ Hemi 5.7V8)
there are probably more options today.

I think I also have a
Robertshaw/Siebe Model 330
'high performance balanced flow' style thermostat in 205 as well

http://www.flowkooler.com/thermos.php?FKSID=d7449f668762853a549d5cc497b43c1f

and that one almost certainly would fit the older style Mopar water neck.

To make a Model 330 thermostat fit in the Magnum v8 water neck you have to grind the opening larger by at least an eighth of an inch....about a 15 minute job with a Dremel tool with a rag stuffed down in the water neck to catch filings.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/05/08 01:40 PM

Running it hotter will help by vaporizing the fuel better, especially in a carbed engine where the fuel is in the manifold for a short time. Also in theory it would be easier to ignite and therefor you could run it leaner. Not to mention since the metal in the chamber would be hotter it would absorb less heat from the explosion alowing the heat to make more expansion preasure.
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/05/08 07:47 PM

The key thing that happens with a higher temperature thermostat is kinda a surprise.

With hotter coolant behind the cylinder wall,
the oil on the wall thins out,
the viscosity goes down,
and there is less friction against the rings.

Running a hotter thermostat
is not much different than running
lower viscosity oil,
except that your main and rod bearings
still get cooler higher viscosity oil.

Not all parts of an engine
need the same lubrication.

At part throttle (not full throttle)
the hotter coolant will heat the intake air.
This is normally undesirable at full throttle when you want maximum horsepower,
but in the case of 'daily driving' part throttle
the heated intake air
makes you use more throttle opening
which raises MAP
and the higher MAP helps push the piston downward on the intake stroke
and allows the engine's other cylinders
to not have to supply horsepower
to draw that cylinder downward against a vacuum.

Complicated, ain't it?

In this way
heated intake air is like
exhaust gas recirculation (EGR)
.....but heated intake air has two disadvantages compared to EGR:

* it makes detonation and pinging more likely and can limit part throttle compression ratio limit

*it takes slightly more horsepower from the other cylinders to compress the hotter mixture on the upstroke of the piston

Notice the newest diesels have gone to 'cooled' EGR? It is better for MPG than either heated intake air or hot EGR.....but it loads the lube oil up with soot
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/11/08 01:44 AM

A little interesting up date here.

Tn. gasoline all is putting %10 ethenol in it now and it didn't seem to affect the miledge when they switched so I tried topping off with e-85 the other day and it took about 5 galons to fill up. Driving it like that didn't seem to change the way it drove at all so I got real brave today and filled up an empty tank with straight e-85 before a 100 mile highway run for a controlled test. Previously with 93 ocatne @ 75 mph I got 27 mpg. Today driving 75 mph on e-85 it got 25 mpg on the same stretch of road the previous test was done on.

The e-85 was 80cents a gallon cheaper than 93 at the same station.
25 mpg at 3.00 = 12 cents per mile.
27 mpg at 3.80 = 14.07 cents per mile

I am sure I could run up the compression with the e-85 also and that would help. I bought some mopar thin head gaskets and will probably get .060 milled from the heads when I put them on and have a straight up alcholic engine.

As for how it runs with the straight e-85 the only differance I noticed was a tad softer sound from the exhaust, normaly it is pretty raspy under heavy acceleration.
Posted By: patrick

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/14/08 12:39 PM

I'm really suprised you didn't need to do a ton of tuning, as the stoichiometric AFR for E-85 is somewhere near 9:1, vs. 14.7:1 for gasoline....
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/14/08 01:38 PM

The way it apears to me is if I wanted max hp then yes I would have to add a buch more fuel and timing, however since I am just leaving everything the same for MPG purposes and simplicity it is fine. I pulled a couple plugs after running most of the tank out and no sighns of metal flakeing or burning or anything abnormal. Some guys told me it would be so lean it would cause detonation even with 100+ octane but it was the oposite, the ocational one or two knocks going up a steep hill were totally gone all together, no knocking whatsoever. It will probably be a couple more tanks of it before I pull the heads for the compression bump and inspection.

I am thinking of jetting up the secondaries a bunch for the e-85 after I do the switch so I can take advantage of the extra fuel and oxygen content. That way I can have my MPG and HP too!
Posted By: mark7171

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/14/08 02:18 PM

Quote:

I'm really suprised you didn't need to do a ton of tuning, as the stoichiometric AFR for E-85 is somewhere near 9:1, vs. 14.7:1 for gasoline....




yeah, my jet set goes to 100.
Posted By: Anonymous

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 05/14/08 05:33 PM

Keep the ports and valves small not sure which part number but there are high swirl heads that would work well also. Use 1.6 rockers on the intake and 1.5s on the exhaust that will allow in more air fuel and keep the velocity on the exhaust side for better scavenging.Get the compression up to 9.5 to one for better torque, stock or RV type cam. Over drive tranny a must. I would toss the thermo junk and go to an aftermarker fuel injection and lighten the car as much as you can. Light weight aerospace brakes and or wilwoods,Light weight wheels narrower than ussual tires also taller than ussual. Cal trac monoleaf springs,or afco mono leafs no caltrac bars.No jack or spare carry less fuel and kick the chubby brother inlaw out.LOL
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/15/08 12:26 PM

consider some 'rear wheel spoilers' ?

2009 Ford Escape, 2009 Mercury Mariner See Aero Boost

DEARBORN, Mich., May 14, 2008 – Cheating the wind with aerodynamic improvements helps the 2009 Ford Escape and Mercury Mariner become more fuel efficient.

Already among America’s most fuel-efficient and environmentally friendly SUVs, the Escape and Mariner receive aerodynamic refinements on top of powertrain upgrades that contribute to an overall estimated 1 mpg improvement in fuel economy for the four- and six-cylinder models.

“Aerodynamic refinements are the most cost-effective ways to reduce fuel consumption,” says Van Stewart, Escape/Mariner aerodynamicist. “Without significantly altering the design of the vehicle, we can find ways to optimize the flow of air to reduce drag and improve fuel efficiency.”

For the 2009 Escape and Mariner, engineers redesigned the front bumper spoiler and added rear tire spoilers for better airflow management.

The front spoiler was extended further over the wheels to diminish drag and was lowered by 40 mm to redirect air flow. The rear tire spoilers help reduce the aerodynamic drag of the rear wheels and tires.

“Thanks to the aerodynamic refinements made to the Escape and Mariner, they are now fully optimized given the current design of the vehicles,” said Stewart.

This is no small feat, because the Escape and Mariner already were aerodynamically efficient designs.

Stewart and his team of aerodynamics engineers tested all aspects of the vehicle to find areas of potential improvements for incremental fuel economy. From underbody shields to door sealing and new mirror designs, the Ford team spent hours in the wind tunnel and with sophisticated computer modeling to analyze airflow patterns and measure drag data.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/19/08 03:19 PM

I guess this really explains the E-85 thing and blows out all the myths about the mpg and A/F ratios. Notice it is from the EPA itself and not some fly by night con artist dude.

http://www.epa.gov/otaq/presentations/sae-2002-01-2743.pdf
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 05/23/08 01:18 PM

Here is a little something neat to read from 360veiw on another thread.


(here's an attempt to figure out gear ratio for highway cruise in a scientific way, based on piston speed and intake manifold vacuum. comments welcome)
------------
Now lets discuss gearing and fuel economy.

In city driving gearing doesn't matter nearly as much as not having a
'heavy foot' or hauling a lot of weight in the bed of the truck.

A vehicle that is either overgeared or undergeared will lose MPG at highway
cruise.

An engine is numerically overgeared if it is not cruising at about
60-75% open throttle.

An engine is undergeared and "too weak for the job"
if it has to operate with its pistons going faster than an average of about
1200 feet per minute when at 75% throttle.

Note that you could reduce engine weakness by turbocharging
as well as the much more common thought to just make the engine larger in
cubic inches. This is the reason nearly all diesels have become turbocharged
in the last 20 years.

How do you calculate this average piston speed?

Multiply the stroke of the engine in inches by two (because the piston goes
both up and down on one rpm) and then divide by 12 to convert inches to
feet. Multiply this by the rpm.

So where does 1200 feet per minute end up for various engines?
Here some examples:

For the 3.58 stroke of 3.7, 5.7, 5.9 Dodge engines:
2011 rpm = 1200 ft/min /( 2 x 3.58 inches/12 inches per ft)

For the 3.405 stroke of the Dodge 4.7V8
2114 rpm = 1200/(2x3.405/12)

For the 3.00 stroke of the Ford 5.0L V8
2400 rpm = 1200/(2x3.00/12)

For the 4.72 stroke of the Cummins Inline 6 diesel
1525 rpm = 1200/(2x4.72/12)

Is it possible for an engine to be made to get its best fuel economy at a
piston speed above the typical 1200 feet per minute?
Yes.
Very thin piston rings, using less than the normal 3 rings,
slippery coatings on piston skirts, extremely hard but slick coatings
on bore walls like "NikoSil" and keeping the bore walls very hot
so that the oil there will be thin and less viscous can all allow the
'best economy' piston speed to be raised but even 'state of the art'
giant marine diesel where nearly every trick is used seldom exceed
1500 feet per minute.

Honda has announced that over the next 5 year period that the major
part of their engine research $ will be spent on ways to reduce internal
engine friction, and this is from a company that NASCAR engine builders
already admit has the best rod and crankshaft bearing material for sale.

Which is more important: having the rpms near this 1200 foot per minute
speed for the pistons, or having the throttle in the 65-75% open range?
Answer: it is more important to be in the 70% throttle range and you should
slow down the rpms to get there. There is not much change in efficiency
when piston speed drops from 1200 down to 800 ft/minute but there is a big
change in efficiency when the throttle goes from 70% open to 40% open.

Why?

Imagine that you have a disassembled engine in front of you. Put a loose
piston in a bore and pull it down against the friction of the rings. It won't
be very hard.

Now imagine that same piston in the bore has the top of the
bore sealed off and has a vacuum sucked of 12 inches of Mercury.
12 inches of vacuum is about 6 psi of negative pressure. If the piston is
4.00 inches in diameter it has an area of about 12.5 square inches
(remember pi R squared but most cherry pies are round?)
6 pounds per square inch times 12.5 square inches = 75 pounds would be
required to pull the piston down - you probably couldn't do it with the grip
of just a couple fingers! An engine running with a high vacuum in the intake
manifold has to do just this, and for eight cylinders!

Engineers refer to this as one of the two parts of "Pumping Losses". The
other part of Pumping Losses is due to pushing the exhaust out the tailpipe.
Most engine owners easily imagine that exhaust loss, accept it, and spend
a lot of time and money on mufflers, headers, Y pipes etc. These same
engine owners would do well to remember the "Pumping Loss" on the intake side
and try to keep it low during highway cruise conditions.

{Note to engineers: Yea, I know, 'negative pressure' does not really exist and
what actually happened is 14.7 psi of air pressure is pushing the underside
of the piston and there was just less pressure on the top of the piston to
create a delta P - but the general public thinks in 'vacuum' terms.
And it is not just the general public - talk to the biologists who think
-100 psi or more of 'negative' pressure pulls water up capillaries to tree
tops}

Setting Gear Ratios to suit the Customer's Expectations

Most auto manufacturers intentionally overgear their vehicles because they
know from experience that customers will bitterly complain about a vehicle
that downshifts to climb a hill.

Engineers know that to give their customers the best possible highway MPG
the transmission would downshift on EVERY hill, but the sales department
reminds them that that every employee at the automaker (including engineers)
will lose their jobs if customers {even ignorant ones} get mad
and buy someone else's vehicle that meets their expectation.

So vehicles are overgeared to 'feel strong' during the 20% of the time they
are climbing hills in Overdrive, even if it means this hurts MPG a bit during
the 80% of the time the vehicle is on level roads or going downhill.

An engine is numerically undergeared if it is trying to cruise in the
'Power Enrichment' zone above about 80% throtttle opening where the
PCM computer greatly enriches the air to fuel ratio from 14.7 to 11.
On most vehicles with automatic transmissions it is not possible to cruise
in OD on level highways in the power enrichment zone because the
transmission will downshift to a lower gear long before the accelerator
is pressed that far.

For the same reason anyone who presses the accelerator down all the way near
the floor whether they are driving in the city, highway, climbing a hill, or
pulling a trailer is going to get about 25% worse MPG than someone who
presses right up to about 70% throttle but never goes over it.

This is why the old advice to install a vacuum gauge
can certainly help MPG if the driver watches it out of the corner of his eye.

When the vacuum gauge reads about 1 to 6 inches of mercury
you are in the fuel guzzling 'Power Enrichment' zone that you want to avoid
except when you want the highest horsepower and accept the higher fuel usage.

When the vacuum gauge is showing about 7 to 9 inches of mercury vacuum
your engine is converting fuel into horsepower at its most efficient level.

Each engine goes into Power Enrichment at a slightly different MAP sensor
level, but if you listen closely to the engine sound you can hear it happen
as the engine gets a bit smoother with the very rich mixture.





I guess acording to that an OD should really help me, I cruise at 75mph with 19 inches vacume.
Posted By: Anonymous

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 06/10/08 11:36 PM

Thanks for the info.
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/12/08 05:32 PM

I need my computer fixed so I can save this thread...this stuff is too great!
Posted By: jcc

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/12/08 06:19 PM

Interesting read, but where did the magic piston speed of 1200 come from, and on what basis?

And would not a wide open throttle show the least pumping loss on a efi system that would be immune from a power enrichment zone if tuned correctly? Of course there would be no reserve power, but maybe a progressive throttle body or something would handle that. So the main advantage on throttle body percentage opening is simply pumping losses? I thought on a carb it was better fuel air mixing and velocity becuase of a partially open throttle, etc. EFI changes all that since fuel is under high pressure and sprayed
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/14/08 03:14 AM

I would like to know where the ideal piston speed figures come from.

As for pumping losses you can slow down the engine to reduce pumping losses.
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/14/08 03:40 AM

When you going to come and get your Stromberg 2bbl?

Just dropped that shiney '65 model BBD that I massaged on to the slant. Fired right up
Posted By: dIc dOc Deity !

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/14/08 10:43 AM



In my real-quick-read here of this topic ...one quick point someone raised before that was not discussed and thought of more seriously.....

That is water-injection.

Using W I ... you can go way leaner in the A/F ratio, put more timing in the motor and use more compression ratio. ..... BUTTTTT ...don't EVER run it out-of-water !

I had a long-ago project(truck/camper/trailer combo) that I did using an old Spearco system that helped a BUNCH but I did not flog-it-out as much as I would have liked to. But now ... I have a vintage Dodge motorhome that I DO want to "flog" this out on now ... as the price of gas is alot diff than back in those days.

More later ... if anyone is interested.
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/15/08 01:47 PM

the 1200 feet per minute piston speed
come strictly from experiments
... no theory to it, just many many dyno tests of brake specific fuel consumption (BSFC)

this book has a good graph showing fuel economy by piston speed and manifold pressure
near page 378:

http://www.amazon.com/gp/offer-listing/0262700271/ref=lp_g_2

or

http://www.amazon.com/gp/product/0262700271/ref=olp_product_details?ie=UTF8&me=&seller=

repeating for emphasis
you can create engines that get maximum fuel economy above 1200 fpm,
but only if you use
special bore coatings (ceramics),
special rings (very thin & hard),
etc

or "chop the Gordian Knot instead"
and do away with
rings altogether

http://www.newscientist.com/article.ns?id=dn8658
Posted By: jcc

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/15/08 03:46 PM

Quote:

I would like to know where the ideal piston speed figures come from.





Well I now know where the figures come from, but I should have asked why is 1200 so magical? Knowing that might open other solutions to ponder
Posted By: Jerry

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/15/08 05:02 PM

1200 is the critical speed of the assembly. as things go faster the change in momentum will end up taking more energy than it can produce.
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/16/08 05:30 AM

The knowledge here never ceases to amaze me...
Posted By: superbyrd

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 07/17/08 06:15 AM

73 charger. 318, wieand action plus intake, box stock 600 holley, 2 1/4" duals, a833 4-spd. OD tranny, 2.94 geared 8 3/4 with sure-grip. have drivin the car everywhere,back and forth to monster mopar weekend at st.louis,(3 hours away) gets 25-27 on the road. cruising at 70-75mph tachs 1900-2000rpm. gets 21-22 around town.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 08/09/08 01:38 PM

Found it !
Posted By: theclutcher

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 08/10/08 01:38 PM

Thinking about pumping losses.
Anybody investigate a controlled vacuum pump to operate only under high vacuum conditions?
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 08/10/08 02:11 PM

I had thought about running two hollow PCV valves directly to manifold vaccume to keep the crank case under the same vacume as what would be above the piston. I figure the vacume would resist up ward movement of the piston during compression and exhaust strokes and not make a hill of beans differance but I never tried it.
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 08/10/08 04:19 PM


http://web.archive.org/web/20040828170715/http://envalve.com/the_envalve.htm
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 08/10/08 05:53 PM

Quote:


http://web.archive.org/web/20040828170715/http://envalve.com/the_envalve.htm




What the heck is this?
Posted By: 360view

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 08/11/08 03:01 PM

It seems to be a design of PCV valve that holds more vacuum on the interior of the engine block,
but adjusts it depending on blowby gas amount.

Just like a dry sump oiling system
it might slightly improve MPG
by reducing windage drag of the moving parts.

The danger of running two conventional PCV valves is that you pull unfiltered outside air from somewhere where the engine is not sealed properly.

Anyone reading this have access to a "Spintron",
that can turn the rotating assembly of a V8 and measure the hp needed?

At typical highway cruise rpms in the 1500 to 2000 range, I wonder how much hp is consumed from internal windage? This could be measured on a Spintron by spinning the engine in normal air pressure, then redoing the test with a vacuum pulled on the block through both valve covers.

Certainly internal windage matters at high rpm:

http://circletrack.com/techarticles/ctrp_0603_oil_pans_windage/index.html

Posted By: Skeptic

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 08/11/08 10:45 PM

Quote:

Quote:


http://web.archive.org/web/20040828170715/http://envalve.com/the_envalve.htm




What the heck is this?


sniff,sniff I smell
I like that it removes "toxins" from the crankcase
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 11/23/08 07:09 PM

A few things I have tried that didn't seem to make any differance in MPG.

I got a 72 340 4spd TQ on it and it is about the same, mabey a little more throttle responce but
Lossened up the valves to reduce over lap and increase vaccume. It made it more responsive and smoother idle and vacume went up but not a noticable differance in MPG.

I have tried monkeying around with metering rods jets timing curve ect and nothing seems to make any differance. I drove it accross the country this summer and it seems to like E-85 but not any differance in mpg.

Since the basic build no amount of tuneing and such has made a big differance. Any gains have been pretty small. Driving slower did not seem to make a differance, never have made 30mpg even doing 50 mph across the plains. Over 65 though it does start droping off. I think it is just turning to many RPM.

If the 318 in my 91 dakota would ever blow up I will put this motor in it along with a 5 spd and the tbi some 92 magnum ex manifolds and 3.23 gears.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 11/23/08 07:15 PM

A pic incase you havent seen one

Attached picture 4833707-DSC01759.JPG
Posted By: Clair_Davis

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 11/24/08 02:56 AM

Nice! New Charger/Magnum wheels? Did you just bolt 'em up, or are you running spacer/adapters for the bolt pattern?

On the mileage changes, you may need to try some additional hypermiling techniques to get any big changes. Many won't work as well on a carb car as EFI, since most if not all EFI cars now cut fuel entirely when closed-throttle coasting, and that can be a big mileage gain. As an example of the difference it (seems to) be able to make, my DD is a 2008 Honda Fit. Little 1.5L engine, 109hp, but all I do is go to work and back (4.5mi) 95% of the time. In town, I'm averaging a little over 30mpg, but the best I can get on the highway is 38.8mpg. The 50-mile trip down to my folk's place I got a ScanGage II indicated 38 mpg. On the trip back, using a pulse-n-glide (slow accel with throttle-off coast in gear, wash-rinse-repeat) between 55 and 65mph, I got an indicated 47mpg. I can't SWEAR if that really worked out to that mileage, as my wife had put 45 miles of in-town driving, but if she got in the ballpark of 27mpg while running to the mall and grocery store, the numbers do work out. That's a 27% increase in already good mileage on the trip down vs. the trip back. Cool!

Clair
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 11/25/08 08:21 PM

With the early b-body rear the rear wheels %100 bolted on. The fronts I had to put the rotor (75 duster discs)in a brake lathe and machine the snout down at an angle to fit inside the wheel because of the wheel not being deep enough, I also still had to run a 7/32 spacer but the wheel is close enough to the hub to be hub centered. Hub centered is important on this swap because the bolt pattern is not %100 the same. It is something like .3 MM different

You can't really tell in the pic but the chargers center cap won't fit the front because the spindle sticks through it but the grease cap can be chromed and installed after the wheel is installed.
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 11/30/08 11:42 PM

So Dave...Is there still a plan in place to jack the CR and go straight E-85? Or has the relocation to Montana changed all of that?
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 12/01/08 05:03 AM

Unfortunately the only e-85 I can find in Mt. is several hours away and not available to the public. I might try bumping the comp a bit more with some milled RHS magnums or mopar aluminum magnums.

The only thing stopping me is the solid barbell lifters won't oil the rockers. I am considering drilling into the bar bell area through the seat but don't know how big of a hole I should drill.
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 12/01/08 05:10 AM

Does Enginequest make a Mag/LA hybrid that allows the shaft mount rockers with a basically Magnum head design?
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 12/02/08 02:20 AM

The only hybrid sort of deal they have is the 318B head and the only non-magnum part it takes is an LA intake.
Posted By: jrwoodjoe

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 12/10/08 04:34 AM

Quote:

A pic incase you havent seen one




Dave, is that the car you have been doing the test with? It looks AWESOME!!

Sorry we were not able to get together while you were in TN. I would love to have had you work on the Barracuda Transmission but with my little one having medical problems I haven't been able to do too much car stuff. What time I have had, I've been spending on the Challenger. Hope your move went well.

Joe
Posted By: patrick

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 01/30/09 05:49 PM

Quote:

Unfortunately the only e-85 I can find in Mt. is several hours away and not available to the public. I might try bumping the comp a bit more with some milled RHS magnums or mopar aluminum magnums.

The only thing stopping me is the solid barbell lifters won't oil the rockers. I am considering drilling into the bar bell area through the seat but don't know how big of a hole I should drill.




you could always plumb external oil lines and put spraybars in the valve covers...or couldn't you just pick up some new solid lifter for an AMC app? of course, then you'd have to get some SBC adjustible rockers....


another thought is mill to get compression up into the 12:1 range and install a water injection kit to control detonation.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!! - 02/02/09 05:08 AM

I would be real scared to put new lifters on a 42 year old cam and some reason the solid lifters are even more expensive then hydraulic lifters.

I am curently porting a set of magnum heads and I will throw in an XE 268 while I am swapping the heads. I also have a set of 1.7 mopar roller rockers I may throw on there while I am at it.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 02/23/09 05:51 AM

I just threw a 6139 T-quad on there and wow it has very sharp response now.! And I already though it was good

I will report any changes in MPG.
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 02/23/09 01:05 PM

Quote:

I just threw a 6139 T-quad on there and wow it has very sharp response now.! And I already though it was good

I will report any changes in MPG.




Well, you have the smaller primaries on there now. 800cfm VS 850.

What model 850 did you have on there?

What rods are you running?
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 02/23/09 08:20 PM

I think the other carb was a 74 440 truck.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 05/18/09 04:39 AM

No improvement with an AVS or the smaller t-quad for mpg but the smaller t-quad did help throttle response a little. I am trying to get the car running right now I am haveing problems with it running like crap when its warmed up. I currently have a 770 street avenger on there that seems to run real good till it gets warmed up.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 06/14/09 07:40 PM

The 770 is not getting near the miledge the t-quad was getting even now I have it running right. It does not atomize the fuel nearly as good. If you watch the venturies when you rev it in the driveway the drops are much larger than they were from the t-quad venturies. I have been getting about 15 in town and 22 on the highway since I got it running right again.

I have a 625 street demon carb I will probably try soon. It is the first Demon carb I have messed with, kinda weird to me how it has smaller secondaries than primaries
Posted By: FuryUs

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 06/14/09 09:07 PM

So 15/22 with the 770 vs what for the TQ?
Posted By: 4speeds4me

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 06/15/09 04:55 AM

Can't remember the previous city numbers, but the HWY was 29, IIRC. I'm thinking it was 22 city...hopefully Dave'll pop back soon.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 06/20/09 04:26 PM

Yeah those numbers are about right. I just traded for another 72 340 t-quad I will build it for this thing and sell the holley, if it don't sell I will try it on the big motor.

As for my big motor I have a Crank and .020 over 340 block, aluminum magnum heads a couple intakes to pick from (M1 single plane, torquer II, and eddy air gap)a comp XE268 cam and 1.7 mopar performance rockers so I am slowly getting what I need. I also have an a-500 to stuff in it now too so according to my calculations a 414 X .69 = 286 so when I get it all in there it should act like a smaller motor than what I have now at cruise but the first 3 gears will be way more fun of course port velocity will be lower and cam over lap will be higher so it may not do quite as good as it does now but I am still thinking mid 20s on the highway. I am also itching to trade the wheels for some 15x7 ralleys to soften the ride and make it a tad more old school look. Of course at the rate I buy/trade parts (still need pistons rods rings bearings)it will be a while before I get the other motor together
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 07/11/09 11:04 PM

Sold the motor today.
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 07/12/09 01:44 AM

Quote:

Sold the motor today.




And so ends the legend! Didn't even see this department before.

My opinion was to leep this in the Tech department because this is technical!

Did you sell it carb to pan?
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 07/12/09 05:38 AM

I sold it with a 71 440 AVS down to the oil pan. If I can hold on to my money (keep the wife out of it )through the weekend I will be buying pistons, rods, rings, bearings, gaskets... for my stroker on monday

Independance day fun, I told my cousins there smoke bombs werent nothing, watch this

Attached picture 5347346-burnout3.jpg
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 09/02/10 05:33 AM

Just got a wild though through my head a minute ago, just for kicks and giggles.

I am building a 414 magnum headed monster for the car, but I have another 273 2bbl cam/lifters and closed chamber 318 heads and thought it would be interesting to see how different the MPG would be with the same basic top end as before but another 91 cubes

I could throw the MPG top end on for a little while before I put the big cam and magnum heads on just for an experiment
Posted By: dIc dOc Deity !

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 09/02/10 06:39 AM

IT'S still ALIVE ... .. the topic that is.

I have not read through all-of-this ......

Has ANYone tried really leaning the carb out and then using water-injection ?
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 09/03/10 03:52 AM

Quote:

Just got a wild thought through my head a minute ago, just for kicks and giggles.


I could throw the MPG top end on for a little while before I put the big cam and magnum heads on just for an experiment




Sampling the local dental floss are we?

Or to many Captain Morgan A&W rootbeer floats?

Go for it!
Posted By: dIc dOc Deity !

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 01/09/11 08:03 AM

Quote:

IT'S still ALIVE ... .. the topic that is.

I have not read through all-of-this ......

Has ANYone tried really leaning the carb out and then using water-injection ?




Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 06/26/11 05:51 PM

Well I sold it, mabey this info should be moved back to the archives.

Comeing soon, super duper MPG II

Shooting for 30 MPG
Posted By: MuuMuu101

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 06/26/11 06:28 PM

I got to read through this thread
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 06/26/11 08:37 PM

Quote:

Well I sold it, mabey this info should be moved back to the archives.

Comeing soon, super duper MPG II

Shooting for 30 MPG




Do your best then try adding an HHO set up.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 07/15/11 06:00 PM

Quote:

Quote:

Well I sold it, mabey this info should be moved back to the archives.

Comeing soon, super duper MPG II

Shooting for 30 MPG




Do your best then try adding an HHO set up.




Every HHO set up I have been involved in made MPG worse or no change at all so sorry Walt I won't drink that cool aid. Real basic physics proves it won't work it just plain takes more energy to seperate the H2 from the O than the energy you get by rejoining them in holy combustion.
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 07/26/11 05:28 PM

The only thing I know was a friend running OTR with an '06 Ram with a Cummins. He got 2.5mpg better grossing 22,500lbs. 12 to 14.5.

It was a primitive set up. Just burning off unburnt fuel.
Posted By: HotRodDave

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 08/02/11 03:59 AM

So 20% of his fuel was just dumping out the tail pipe un-burned? Either he changed something else like mabey added a chip or taller gearing or... mabey he doesn't want anyone to know he got suckered so he is throwing out some dreamed up number The only real world experiance I have had proved that the physics was right, takes more energy to run them than what you get back from them.
Posted By: Rug_Trucker

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 08/02/11 05:59 PM

Nope. I've known him since 1978. He isn't a BS'er. It was a bone stock Cummins, and gearing.

You can believe it if you want.
Posted By: Rob C

Re: Super duper MPG 273/318 experiment ! NUMBERS!!!!!!! - 08/23/13 03:14 PM

It all in the cruise rpm and the locking up of the converter all in the most Efficent spot. I so believe hot rod. This is not the first time I heard this and two very good and long time freinds told me the same thing. The truck simply just hot better mileage on the hwy. towing something heavy.

I think it may having something to do with the converter and the rpm range which the engine is running at while towing forcing the converter to work better/harder.