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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: 4speeds4me]
#47709
03/20/08 09:12 AM
03/20/08 09:12 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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I Live Here
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Posts: 16,123
Grand Haven, MI
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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.
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 273/318 experiment !!! UPD
[Re: patrick]
#47710
03/20/08 09:30 AM
03/20/08 09:30 AM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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I Live Here
Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
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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....
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 273/318 experiment !!! UPD
[Re: patrick]
#47711
03/20/08 10:14 AM
03/20/08 10:14 AM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
OP
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OP
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Kalispell Mt.
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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 
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 273/318 experiment !!! UPD
[Re: Grassosgarage]
#47712
03/20/08 10:24 AM
03/20/08 10:24 AM
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Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
HotRodDave
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OP
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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.
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 273/318 experiment !!! UPD
[Re: HotRodDave]
#47713
03/20/08 11:18 AM
03/20/08 11:18 AM
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Joined: Jan 2003
Posts: 6,988
Warren, MI
Jerry
master
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master
Joined: Jan 2003
Posts: 6,988
Warren, MI
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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.
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: Jerry]
#47714
03/20/08 11:40 AM
03/20/08 11:40 AM
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Joined: Feb 2003
Posts: 2,304
WI
RestoRick
top fuel
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top fuel
Joined: Feb 2003
Posts: 2,304
WI
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This is interesting... Hughes Modified Magnum IntakeScroll down and read the mileage increase claims.. Rick
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: BigTerry]
#47717
03/20/08 05:55 PM
03/20/08 05:55 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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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....
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: Supercuda]
#47718
03/20/08 06:12 PM
03/20/08 06:12 PM
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Joined: Nov 2006
Posts: 664
Stuart, FL
Grassosgarage
mopar
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mopar
Joined: Nov 2006
Posts: 664
Stuart, FL
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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.
'70 Cuda 440/auto
'70 Duster 340/4sp project
'70 Satellite convert 318 survivor
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: Grassosgarage]
#47719
03/20/08 06:16 PM
03/20/08 06:16 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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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.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: Supercuda]
#47720
03/20/08 06:24 PM
03/20/08 06:24 PM
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Joined: Nov 2006
Posts: 664
Stuart, FL
Grassosgarage
mopar
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mopar
Joined: Nov 2006
Posts: 664
Stuart, FL
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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!
'70 Cuda 440/auto
'70 Duster 340/4sp project
'70 Satellite convert 318 survivor
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: Grassosgarage]
#47721
03/20/08 06:26 PM
03/20/08 06:26 PM
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Joined: Jul 2003
Posts: 6,167
Maryland
GO_Fish
master
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master
Joined: Jul 2003
Posts: 6,167
Maryland
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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.
Scott B.
"I'm a self-made man... I started with nothing, and I still have most of it!"
68 360 rusty B'cuda 'vert (GO Fish)13.59@ 98.72 mph
69 340 GTS stock 14.18@ 95.60 mph
01 5.9L Ram 1500 Quad Cab 4x4
01 3.5L 300M 16.23@ 86.97 mph
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: HotRodDave]
#47723
03/20/08 08:38 PM
03/20/08 08:38 PM
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Joined: Jul 2003
Posts: 6,167
Maryland
GO_Fish
master
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master
Joined: Jul 2003
Posts: 6,167
Maryland
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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.
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Re: Super duper gas miledge 273/318 experiment !!! UPD
[Re: Grassosgarage]
#47726
03/21/08 08:03 AM
03/21/08 08:03 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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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?
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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Coasting in neutral will help to but some guys disagree about that also, more