So, I was wondering something. By adding aftermarket performance stuff to your car (N/A & Forced Induction), does it give you better gas mileage, or do you actually use up more fuel than a stock engine, since you're creating/freeing up more power? I know things like plugs, wires, air filter, etc will help you with your fuel mileage, but what about the other stuff? (cams, BBTB/BIM, intake, exhaust, turbo, S/C, nitrous, etc....)


Just curious. dunno

 

It really depends on which mods.

On a Bone stock car, a CAI helped my gas mileage about 2-3 MPG.

BTB/BIM didn't hurt it, or help it.

Cams should hurt the fuel economy.

The turbo was HORRENDOUS. I dropped to 18 MPG when I first got it. It's back up to about 24 MPG now. Before I was in the high 20's low 30's.

The SC was just as bad. It was first installed on the Elantra, It leaked more fuel than it burned. Once we got that fixed and a retune, it settled back down into the mid 20's with I think a best of 27mpg.

 

The gammut of N/A stuff that I did (intake, BBTB, BBIM, ported head, 2.0L XD cam, HVE 4-1 header, full exhaust, Apexi S-AFC) ended up getting better gas milage on the whole so long as I didn't have my foot in it.

Pulled a 34mpg more than a few times on the freeway doing somewhere between 85 and 100 on the way to Kansas to visit the family. That's better than 450 miles on a full tank of gas...

Forced induction is usually the reverse; expect it to go down. The severity of your fuel mileage loss will depend on your setup and your tuning options. I was able to pull 31mpg on the low compression (9:1) motor, 550cc injectors, 70psi+ fuel pressure, Walboro 255lph pump and the Haltech running the show. I'd expect to see similar results even with the turbo bolted on, only because the turbo I'm picking is big enough to NOT spool at highway load wink