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post #1 of (permalink) Old 05-23-2001, 11:06 PM
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4.3 mods for mpg

I have a 2000 a/t 4.3, and while the gas milage is pretty close to the GM prediction (i get about 16mpg), im in high school and am having trouble with dropping 25 bucks for gas practically every week and a half. oh yes, and the truck is 2wd. i was wondering what mods could i make to the engine, exhaust, etc. to get better gas mileage without loosing power (a gain would be nice). i have heard that performance exhaust makes mileage worse, is that true? i know a k&n would help, but not as much as it would with exhaust right? so im kinda lost on those 2 things. also i have gone from the stock 205/75/15 (about 27") to the 235 bfg a/t's (about 29-29.5"), i think my stock gearing is something like 3.08??... at 70mph i am at 2100 rpm...would a regearing help? also, i have yet to have my computer reprogrammed for those tires, so that means that my auto tranny shift points are off, could that be hurting my mileage? anything else im missing that can help with mileage??? ive tried the free route and have been running around town without a tailgate, havent seen any improvement.


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post #2 of (permalink) Old 05-24-2001, 12:53 AM
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Re: 4.3 mods for mpg

Try a free flow exhaust system and maybe a K&N filter....


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post #3 of (permalink) Old 06-13-2001, 10:53 AM
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Re: 4.3 mods for mpg

Perf. Exhaust will boost power and MPG: Less restriction of airflow out the engine = less strain on engine. K&N will give more air into the engine w/ less restriction of airflow into the engine = less strain on engine. Both would be a good idea, K&N first (cheaper) the save for exhaust.


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post #4 of (permalink) Old 06-13-2001, 11:59 AM
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Re: 4.3 mods for mpg

after i put bigger tires on my truck, 235 -> 31s, i lost mpg. i have a 3.73 gear ratio. so it would benifit to having either a reprogram of your computer or change your gear ratio - either regear, or get a used rearend that has a better ratio.


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post #5 of (permalink) Old 06-13-2001, 02:38 PM
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Re: 4.3 mods for mpg

Get a K&N filter. It's the best $40 I ever spent on my truck `96 with the 4.3L. It boosted power noticeably and I think MPG's went up a little.

If you've got a lot of miles on the engine, a new set of plug wires might help too. Get good ones (I like Accel wires), cheap ones are 'cheap' and I've had stock and inexpensive wires cross-fire and arc to the body in the past. New plugs won't add as much (~$6/ea - they are platinums in the Vortec's), and since newer engines run so lean anyway, the plugs normally don't foul out.

Low restriction exhaust will help some, too, but I think I listed the biggest bang for the buck above.

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