I have a question on gas mileage after upgrades on the engine. I've always wondered if putting on a short ram/cold air intake, hotter spark plugs, upgraded ignition wires, header, exhaust, etc. affects the gas mileage on our cars in any way. Does it improve it or worsen it. Any insight will be appreciated. Thanx!



Brian
West Melbourne, FL

1998 Mitsubishi Eclipse RS(White)
1965 Ford Falcon

Mods: AF/X UDP, NGK-BKR5E spark plugs, Custom CAI. Best et...16.31 @ 85.50 mph with custom ram air intake.***That was with my old engine. I hydrolocked it, so now I have a completely stock engine***

Here's some good stuff on that one...

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=4&topic_id=89530&mesg_id=89530&listing_type=search

I found, with adj. cam gears, if you adv. the exhaust a few degrees it seems to bump up the mpg. I had 'em +3 and averaged around 26ish, I turned them back to stock for inspections and since then I'm sittin around 23-24. Maybe other factors, but that was the only thing I've really screwed with other than changing oil.

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'95 GS w/ t3/t4b
FMIC, diy piping & RFL BOV
MS2-Extra Fuel&Spark
50 lb/hr Holley injectors w/ 1:1 RRFPR
JE 8.8:1 dish w/ Hastings Rings
Eagle Rods w/ ARP bolts
ARP Head studs
Mild port/polish head
3" custom DP/cat section, 3" PIT catback
dual MBC - 12 psi / 20psi

The single biggest improvement that you can make besides keeping the car tuned up properly and having your tires inflated is in your right foot.

I will admit that adjusting the exhaust cam 3* has my curiosity piqued tho

Erik P.
Official 2GNT thread Hijacker
Some say that he's driven over more Covenant than he's shot, and that his grenades aren't where you'd expect them to be...
All we know is, He's not The Stig... But he is The Stig's Spartan cousin!

Intake and exhaust will improve MPGs, but as Ronin said, careful right foot modulation (smooth acceleration, steady cruising at conservative speeds, etc.) will stand to increase any other steps you take.

You're lucky to have a car already pretty good at MPGs. I used to get more than 35mpg on the highway at 80mph with the AC with a fully built engine. I wouldn't go nuts modifying the car for MPGs, though. Maintain it and document your changes and gains.

I noted after i put on my header and exhaust my gas milage didnt change all that much, i was getting around 23-25 mpg alot of city and freeway. After i got my throttle body bored out i noticed a much larger change between 26-30mpg this was also with alittle bit more freeway driving though. So in reality if i drive the same way but with intake,exhaust and bored TB i would expect mabye 2-3 mpg difference. Lead foot is a definate cause of bad gas milage good way to counter it, drive more on the freeway.

Mods do not really affect gas mileage, execept in the city. It is more about how much your foot is on the pedal.

I built my motor, JE pistons, Crower rods, Crane Cams, Unorthodox UDP, MSD & ACCELL, AEM V2 CAI, cat back exhaust, plus a full port & polish.

I average 28 - 32 MPG highway, and I was shocked at first. When I drive in the city, I do see my needle dropping.