• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Exhaust affecting gas mileage??

lostcreek21

NAXJA Forum User
Location
Gresham oregon
Hey guys, recently I took off my cat and I put on a cherry bomb. I noticed that my gas mileage went down 4-5 MPG. I also just put 31x11.5's on but I was wondering if my exhaust could be affecting my mileage. I was thinking that there is not enough back pressure but I'm no expert on exhaust so I don't know. Does anyone know if that could be it? I didn't think that going to 31's would drop my mileage so much, so I'm exploring different options. Thanks
 
IMO the tires are probally what is causing you MPG to go down. I have been running no cat for as long as I have had the rig. The MPG goes up when I run smaller/stock size tires.

Opening up the exhaust should give you more power and better MPG. IMHO the exhaust is not your problem
 
Regearing will certainly help but gas mileage won't be completely restored because you'll still have the extra rolling resistance and rotational inertia of the bigger tires.
Don't forget that with the bigger tires, your speedo and odometer will underread (and give you less mpg than you're actually getting), so you'll need to change the speedo gear to correct this.
 
Back
Top