Re: Super duper gas miledge 273 experiment !!!
[Re: Mr.Yuck]
#47547
11/14/07 01:13 PM
11/14/07 01:13 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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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.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47549
11/14/07 02:33 PM
11/14/07 02:33 PM
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Anonymous
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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
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47550
11/14/07 06:54 PM
11/14/07 06:54 PM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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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.htmlhttp://en.wikipedia.org/wiki/Mazda_MilleniaWithout 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/247Mahle 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/
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Re: Super duper gas miledge 273 experiment !!!
[Re: 360view]
#47551
11/14/07 11:08 PM
11/14/07 11:08 PM
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Joined: May 2007
Posts: 1,443 Maryland
Dads426
pro stock
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pro stock
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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.
2012 422 Allstars NSS Champion 2013 422 Allstars NSS Champion 2014 422 Allstars NSS Champion
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Re: Super duper gas miledge 273 experiment !!!
[Re: Rug_Trucker]
#47553
11/15/07 04:33 PM
11/15/07 04:33 PM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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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
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]
#47554
11/15/07 04:39 PM
11/15/07 04:39 PM
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Joined: Jan 2003
Posts: 4,820 near Alexandria, VA
Gas_Bandit
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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.
2003 Mercury Marauder, 34k miles, 3.73s and custom flash tuned 1981 Camaro, 350 w/ Holley Stealth Ram MPEFI, Sportsman heads, roller cam, self-burned chips, wideband O2 1983 Firebird TA 1993 Saturn SL2 83k
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Re: Super duper gas miledge 273 experiment !!!
[Re: patrick]
#47555
11/15/07 04:54 PM
11/15/07 04:54 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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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???
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47556
11/15/07 06:14 PM
11/15/07 06:14 PM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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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.
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]
#47557
11/16/07 01:16 AM
11/16/07 01:16 AM
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Joined: Jan 2005
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HotRodDave
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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.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47558
11/16/07 10:44 AM
11/16/07 10:44 AM
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Joined: Jan 2003
Posts: 7,131 Amarillo, Texas
BBR
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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.
Drag Week 2011 - 77th place - DD Drag Week 2012 - 2nd place SRBB N/A Drag Week 2014 - Kapooya RMRW 2018 RMRW 2020
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Re: Super duper gas miledge 273 experiment !!!
[Re: 360view]
#47561
11/19/07 08:58 AM
11/19/07 08:58 AM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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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....
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]
#47562
11/19/07 10:36 AM
11/19/07 10:36 AM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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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.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Super duper gas miledge 273 experiment !!!
[Re: HotRodDave]
#47563
11/19/07 12:43 PM
11/19/07 12:43 PM
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Joined: Jan 2003
Posts: 16,123 Grand Haven, MI
patrick
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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....
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: dulcich]
#47565
11/19/07 02:28 PM
11/19/07 02:28 PM
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Joined: Feb 2003
Posts: 1,665 Milwaukee, WI
Prince_Valiant
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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.
1979 Dodge Lil' Red Express - 360 rwhp, 13.2 @ 103mph 1968 Coronet: 318, 2.76, 15.2 @ 92mph! (SOLD) 1976 Valiant: 360, 3.90, 12.90 @ 106 (SOLD) 1989 Shelby CSX #500/500
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Re: Super duper gas miledge 273 experiment !!!
[Re: Prince_Valiant]
#47566
11/19/07 03:19 PM
11/19/07 03:19 PM
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Joined: Jan 2003
Posts: 27,451 So Cal
autoxcuda
Too Many Posts
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Joined: Jan 2003
Posts: 27,451
So Cal
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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.
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