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Re: Super duper gas miledge 273 experiment !!!
[Re: Prince_Valiant]
#47527
11/12/07 10:32 AM
11/12/07 10:32 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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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.
Last edited by patrick; 11/12/07 10:39 AM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Super duper gas miledge 273 experiment !!!
[Re: patrick]
#47528
11/12/07 10:47 AM
11/12/07 10:47 AM
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Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
Rug_Trucker
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,610
Not2farfromNashville, TN
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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.
"The only thing to do for triumph of evil is for good men to do nothing"
"NUNQUAM NON PARATUS!"
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Re: Super duper gas miledge 273 experiment !!!
[Re: mopowergtx]
#47529
11/12/07 12:04 PM
11/12/07 12:04 PM
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Joined: Aug 2006
Posts: 540
murfreesboro, TN
Qbird
mopar
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mopar
Joined: Aug 2006
Posts: 540
murfreesboro, TN
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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?....
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Re: Super duper gas miledge 273 experiment !!!
[Re: mopowergtx]
#47534
11/12/07 01:59 PM
11/12/07 01:59 PM
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Joined: Aug 2006
Posts: 540
murfreesboro, TN
Qbird
mopar
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mopar
Joined: Aug 2006
Posts: 540
murfreesboro, TN
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Quote:
Gas is expensive.  Thats right it was $50. 
What was the bet???...did I sleep through this or something?
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Re: Super duper gas miledge 273 experiment !!!
[Re: BigBlockMopar]
#47535
11/12/07 02:44 PM
11/12/07 02:44 PM
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Joined: Jan 2003
Posts: 4,558
Montana
FuryUs
master
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master
Joined: Jan 2003
Posts: 4,558
Montana
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Quote:
Why the .060 overbore?
I believe that was to unshroud the bigger Magnum valves.
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47538
11/13/07 10:54 AM
11/13/07 10:54 AM
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Joined: Jan 2003
Posts: 5,387
Pikes Peak Country
TC@HP2
master
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master
Joined: Jan 2003
Posts: 5,387
Pikes Peak Country
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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.
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47539
11/13/07 11:35 AM
11/13/07 11:35 AM
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Joined: Feb 2003
Posts: 18,263
Charlotte, NC
Orange_Crush
Belieber!
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Belieber!
Joined: Feb 2003
Posts: 18,263
Charlotte, NC
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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.
1970 Dodge Charger R/T Hemi Orange U-code 4-speed
1971 Jaguar E-Type Series 3 V-12 4-speed 2+2 Signal Red.
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47542
11/14/07 08:09 AM
11/14/07 08:09 AM
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Joined: Jan 2006
Posts: 8,162
USA
360view
Moparts resident spammer
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Moparts resident spammer
Joined: Jan 2006
Posts: 8,162
USA
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Some thoughts: Read up on "Atkinson Cycle" "Miller Cycle" "Delayed intake valve closing" http://en.wikipedia.org/wiki/Atkinson_Cycleand 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.pdfThe 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/3dgkodthere 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/kgqlzGood luck and please keep posting on your project.
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47544
11/14/07 11:42 AM
11/14/07 11:42 AM
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Joined: Jan 2003
Posts: 1,692
Seattle WA
RichV
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,692
Seattle WA
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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.
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Re: Super duper gas miledge 273 experiment !!!
[Re: RichV]
#47545
11/14/07 11:57 AM
11/14/07 11:57 AM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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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.
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47546
11/14/07 12:24 PM
11/14/07 12:24 PM
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Joined: Aug 2003
Posts: 4,384
Madison Wi
NTOLERANCE
master
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master
Joined: Aug 2003
Posts: 4,384
Madison Wi
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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.
I used to care but....... things have changed
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