3" lift dropped my mpg 4 miles
03-08-2017, 09:12 AM
#21
JK Jedi
I have a gas motorhome as well. Anytime I get down on the thought of my jeep getting 13-14mpg, I just remember that the motorhome loaded down and towing a 5k lbs jeep gets on average, 6mpg. 
03-08-2017, 09:32 AM
#22
Former Vendor
There is definitely a point of no return once you start adding heavy bumpers, carrying tools and running giant lifts.
With a relatively stock late model JK on a 35" tire and a lighter weight 17" wheel, light skid plating and weight conscious bumpers, a proper regear and programmer will get you within an mile or two to the gallon of where you were stock. With a 3.6 JK auto, 4.56-4.88 is the sweet spot with a 35" tire depending on whether you do more around street vs freeway driving.
A 3.8 JK is doomed to languish with eco terrorism type fuel economy, especially with the 4 speed auto. It's very sensitive to load and heat, but fuel economy isn't effected as strongly by RPMs, so don't be afraid to go deep. The 42RLE has internals that are about as big as a loaf of bread, tall gearing and a slushy torque convertor that all work against you, so don't be afraid of 5.13 gears and 35" tires, they do just fine.
With a later model JK, you can do a fully built, awesome JK on 35" tires that has manageable fuel economy (by Jeep standards) as long as you are conscious of weight.
With a relatively stock late model JK on a 35" tire and a lighter weight 17" wheel, light skid plating and weight conscious bumpers, a proper regear and programmer will get you within an mile or two to the gallon of where you were stock. With a 3.6 JK auto, 4.56-4.88 is the sweet spot with a 35" tire depending on whether you do more around street vs freeway driving.
A 3.8 JK is doomed to languish with eco terrorism type fuel economy, especially with the 4 speed auto. It's very sensitive to load and heat, but fuel economy isn't effected as strongly by RPMs, so don't be afraid to go deep. The 42RLE has internals that are about as big as a loaf of bread, tall gearing and a slushy torque convertor that all work against you, so don't be afraid of 5.13 gears and 35" tires, they do just fine.
With a later model JK, you can do a fully built, awesome JK on 35" tires that has manageable fuel economy (by Jeep standards) as long as you are conscious of weight.
03-08-2017, 06:50 PM
#23
JK Enthusiast
Thread Starter
I did some comparisons. The last few days I've just been driving around locally and I'm getting 18.7. Driving highway speeds I get 17 or worse. Just the opposite of what you'd think.
03-20-2017, 03:43 AM
#24
JK Newbie
Join Date: Mar 2017
Location: Long Beach, CA
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Thank you to everyone for the advise.
I went ahead and purchased the Superchips Flashcal, reprogrammed for 35" and saw a gain of 2-3 MPG on a 80 mile road trip, roughly 18.5-19mpg according to dash info.
1 day later, I regeared to 4.88's and drove +\- 150 miles. Even though I have a manual transmission I still went ahead and reprogrammed to 4.88's with the Flashcal (not sure if it makes a difference). After those 150 miles, my averge MPG was 19 miles! Pretty surprising.
I went ahead and purchased the Superchips Flashcal, reprogrammed for 35" and saw a gain of 2-3 MPG on a 80 mile road trip, roughly 18.5-19mpg according to dash info.
1 day later, I regeared to 4.88's and drove +\- 150 miles. Even though I have a manual transmission I still went ahead and reprogrammed to 4.88's with the Flashcal (not sure if it makes a difference). After those 150 miles, my averge MPG was 19 miles! Pretty surprising.
03-20-2017, 01:44 PM
#25
Former Vendor
Thank you to everyone for the advise.
I went ahead and purchased the Superchips Flashcal, reprogrammed for 35" and saw a gain of 2-3 MPG on a 80 mile road trip, roughly 18.5-19mpg according to dash info.
1 day later, I regeared to 4.88's and drove +\- 150 miles. Even though I have a manual transmission I still went ahead and reprogrammed to 4.88's with the Flashcal (not sure if it makes a difference). After those 150 miles, my averge MPG was 19 miles! Pretty surprising.
I went ahead and purchased the Superchips Flashcal, reprogrammed for 35" and saw a gain of 2-3 MPG on a 80 mile road trip, roughly 18.5-19mpg according to dash info.
1 day later, I regeared to 4.88's and drove +\- 150 miles. Even though I have a manual transmission I still went ahead and reprogrammed to 4.88's with the Flashcal (not sure if it makes a difference). After those 150 miles, my averge MPG was 19 miles! Pretty surprising.