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20mpg with a 5.5" lift!!

Stang5lgt said:
My 89 XJ got 20mpg once in awhile on 33s. Usually it got 17-18 mpg range. It is pulling 17 mpgs this last tank on 35s and 5.5 lift. 5 speeds makes a big difference. Plus my XJ is 2 door with no options so it pretty light weight.
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I heard some where that the renix is better on gas miliage anyways. but I could be mixing up my facts.
 
20mpg?

With plenty of wax to cut down on wind resistance, and with properly inflated tires - it's possible.























If he coasts downhill all the time. :D

.
 
Yeah...no way! Although I AM a little suprised with what I'm getting. I get around 13.8-14 and I've got a 6" w/ 35s. Maybe the 4.56 is helping out?
 
Its not THAT far out... I got 17-19 on 4.5 with 32's (geared 3.73) and my 4.6l stroker in mixed driving, and now get @15 at 5" on 33's (geared 4.30)
 
with proper gearing it is possible to restore gas mileage. the lift itself doesn't adversely affect your gas mileage, its the oversized tires that do that.
 
Only thing that hurts ya on the lift is more air draggin underneath. But doesn't add upto alot. Tires do most the hurting. My XJ got 22-24 mpg before I lifted and put bigger tires on it. And I checked every tank since I have no gas gauge. When I had my Auto 92 XJ it was gas hog compared to my 89. It only got about 17-18 mpg with stock tires on the Highway. I was pretty disappointed so I sold it.
 
My 92 Laredo gets better mileage than my 99 XJ did. I only averaged 18-19 mpg in my 99 and I have been averaging 21-22 in my 92. Both are/were fully equipped w/ pwr windows, locks, and a/c. The only difference is my 92 is a 5spd. I'm hoping the lift/tires won't hurt my 92 as much as it did my 99, the 99 dropped down to like 12-14mpg after the 32's were installed. Main thing that killed it was the lack of being able to maintain overdrive on the highway. While I probably won't be able to use 5th all that much I think 4th on the manual will be a more highway mileage friendly gear than 3rd in the auto.
 
btw, that is a pretty clean looking XJ for the money. I'd offer him 2500$ if I still needed a Jeep. I's then lose the rims/tires and go for some 33's. Does seem a bit short for a 5.5" lift though. Doesn't appear to have a lot of fender to wheel gap, especially considering those are only 31's.
 
DutchVDub said:
My 92 Laredo gets better mileage than my 99 XJ did. I only averaged 18-19 mpg in my 99 and I have been averaging 21-22 in my 92. Both are/were fully equipped w/ pwr windows, locks, and a/c. The only difference is my 92 is a 5spd. I'm hoping the lift/tires won't hurt my 92 as much as it did my 99, the 99 dropped down to like 12-14mpg after the 32's were installed. Main thing that killed it was the lack of being able to maintain overdrive on the highway. While I probably won't be able to use 5th all that much I think 4th on the manual will be a more highway mileage friendly gear than 3rd in the auto.
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You should be ok with lift and tires. I lost couple mpgs. I even squeezed 21mpg couple times with 33s and stock 3.08s Never got to use OD . 4 gear everywhere.
 
Interesting thoughts...

Anyone drive by tach, watch manifold vacuum? My last trip to GJ I changed my driving strategy, picked up 3 MPG. In a nutshell I kept the RPMs up and used less throttle to do it. I drove a little (a little-lot???) fast both directions.

What RPMs do you cruise at?
 
Thats what RPM I was trying to keep my 99, a little harder w/ the auto though. I found that if I kept my speedo at 70mph (uncorrected reading mind you) it got quite a bit better mileage on the highway than trying to keep it at 75mph, stayed in OD more too.
 
Interesting discussion that's evolved after the original post. Also interesting that nobody mentioned the big-azz platform up top that should help eat another 1-2mpg...that's a boatload of aerodynamic drag!

I've seen some pretty sketchy "calculations" for gas mileage on this site before, and know that even a good calculation will be wrong if the speedo gear is wrong - I still feel this one had to have been one or both of those problems.

Whatever...I'm not in the market for anything that gets less than 30mpg anyway. :shrug:

Jim www.yuccaman.com
 
Yucca-Man said:
Interesting discussion that's evolved after the original post. Also interesting that nobody mentioned the big-azz platform up top that should help eat another 1-2mpg...that's a boatload of aerodynamic drag!

I've seen some pretty sketchy "calculations" for gas mileage on this site before, and know that even a good calculation will be wrong if the speedo gear is wrong - I still feel this one had to have been one or both of those problems.

Whatever...I'm not in the market for anything that gets less than 30mpg anyway. :shrug:

Jim www.yuccaman.com
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Find a diesel XJ.
 
Or do a TDI swap into one. I'm not sure its been done before but I'm going to do it whenever my 4.0 goes out. I know the VW TDI is a great engine and can be made to make really good power and still get over 40mpg. Scarily enough an XJ isn't much heavier than a B5 chassis Passat and the 2.0L TDI that came in those didn't have much problems moving those things along at a respectable rate.
 
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