Hey All, I am planning my dream trip across the country since I have my Jeep. I want to do a lift, new wheels and bigger tires have 32s now) but I dont want to get 13 MPGs going across the country.

Anyway does a lift decrease MPG?

Thanks in advance
Jim

 

Doubtful a lift (by itself) will impact mpg too much. It changes the aerodynamics slightly due to the difference in air flow below the jeep, but doubt you'll notice anything. However, larger tires (heavier) and/or wider tires (more contact friction) will certainly impact your mpg. I've got a lift and 35s w/an automatic and regeared to 5.13s and usually see around 15 in town and when I get on the highway I see around 15. That's on a 4dr and usually drive 80 or a little over when I'm on the highway.

 

Get the lift and tires, and swap to the stock tires for the cross country drive.

By the way, are you re-gearing with the bigger tires? Depending on the size difference, you'll lose some mpg's with the tires, and may pick a few back up with the gears.

 

Quick and simple answers:

Will a lift affect MPG? Yes, how much depends on the lift hight (aerodynamics as mentioned) it will be noticable, but not bad.

Will larger tires affect MPG? Yes. The bigger and heavier the greater the affect on MPG.

What can I do about it? First you can regear, that will be your biggest gains, it will put you back close (you will never get better than) stock with lift and larger tires. Second you can get a quality programmer (superchips or hypertech) to correct all your computer settings (gears, tires size, etc) and get a few extra ponies. Third you can adapt your driving style to be very conservative.

 

Thanks for the quick replies, I want the Tera Flex 2.5" lift, and I am contemplating 35s but I am not sure I want to regear, I am sure Jeep will void my lifetime warranty with a regear. I am also trying to save some money for some land and a Log Cabin.

Either way I start with the lift and go from there.

Thanks
Jim

 

Installing a Cold Air Intake will help you get some of the MPG back

Stop in if you go through Texas

Sean at SLC

 

You are actually more likley to loose your lifetime warranty if you dont regear. Regearing will allow what stock parts that remain to operate closer to the stresses and thresholds they were designed for.

 

Be sure to do some homework before deciding on 35's. There are plenty of re-gearing threads to browse through, so you'll get a good cross section of opinions on just how much power you'll lose, and a better idea of whether it is worth going that big without gears.

There are quite a few warranty related threads also. One thing to keep in mind here is that any mods can potentially void the warranty. (ie, bigger tires with no other mods) Just depends on what is done and which dealership you take it to.

-one post that caught my eye not too long ago was from someone that went in for warranty work on his transmission. Dealer saw the big tires and asked if he had regeared. He had, so new tranny approved. If he had been on stock gears, the dealer would have denied the claim due to the extra stress placed on the transmission from the bigger tires.
-another recent post was from someone that had a dealer install new gears. He was driving cross country, the front gears blew up, which also took out the transfer case. Local dealer denied the claim. Original dealer that did the gear install denied it also. (pretty bad when a dealership will not warranty their own installs...)

So, it's all about what mods you do, and how any particular dealership chooses to deal with them. Talk to your dealership before you assume something will or will not void some part of the warranty.

 

Hey SLC I appreciate the offer, I may take you up on that. Some neat areas I went thru around there. I loved the Pecos area.


nthnuf-I will talk to them before I do anything.

Thanks

 

Lifting the jeep 5"+ (3" from lift + 2" from tires) inches will affect the aerodynamics of the JK significantly at highway speeds. Not only will it increase the projected frontal area, it will increase the airflow under the vehicle increasing scrub drag and lift (yes lift). The stock aerodynamics are poor, particularly with the top off and the JK is relatively heavy so the effects may not be as noticeable, but they will be there.

The impact on MPG will be disguised at lower speeds by the effects of larger tires, gearing and additional weight, but specially above 70 MPH (on a different thread one owner had his JK to 105 MPH) there will be a notable difference.