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Old 03-06-2008, 01:10 PM   #5 (permalink)
EcoModding Lurker
Join Date: Mar 2008
Location: KY
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A rambling response

Thanks for the quick responses, all good ideas... THM350 or THM400, either way a 3-speed with no overdrive, which will obviously have to go. I'm probably wildly short of stock mpg because of a crap air filter, crap gaskets, exhaust corrosion, and excessive drag (especially from brakes). I'm not at all worried about pulling it back up to 15 mpg, this is all to get me to 20. I do like the idea of bigger, thinner wheels, they just take a backseat to the challenge at hand. I'll have to look into whether an undertray is easier/appreciably more effective than a front air dam. Or you could tell me, haha.

Johnpr you are certainly on point with all your ideas, excellent list, and indeed I'm sure most would pay for themselves. My to-do list grows exponentially. Do you say new shocks for the lowering benefit? If so I would expect the relative benefit of a front air dam or especially an undertray to decrease.

The rest of the recommendations, intake/exhaust and EFI, highlight a particular problem I'm having with spec'ing the engine. If it's already of sufficient torque to move the van, any breathing and thus hp gains from exhaust will seemingly encourage burning more fuel with little added usefulness. Furthermore, the stock exhaust manifold lends itself to low-end torque and vans seemed plagued with ill-fitting headers. With the intake, I don't want to upgrade the carb, im sorry i meant throttle body, only to have the engine always choked off by the throttle plate anyway.

Finally, EFI is tough to justify because of the narrow application. In short I can tune the carb, im sorry throttle body, for my application and the advantages of an adaptive EFI system all but disappear, save for cold temperatures and the minor losses inherent in only using one injector.

Thanks for the thought-provoking answers, you guys are awesome! i really do try to keep these things short. If im wrong about anything, and im sure i am, do tell me. Thanks!
1987 Chevy G20 high-top van - 305, TBI, 11MPG on its only trip
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