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What do you get for gas millage

3.55 gears, 5spd, 4.0 HO, 32x11.5 tires and I'm averaging around 18mpg
 
'87 with a rebuilt Renix. 5.5" lift, 32" Mud Terrains with 3.55:1 = 13mpg on a good day.:smsoap:

That's why I'm driving my not so sexy '90 Honda Pacific Coast, 47mpg rocks!
bike.gif
 
13 mpg! I just had the O2 sensors changed, but I've been stomping on it since the 4:56 gears are broken in. I've done 125 miles on 1/2 a tank! lol

Last tank, before the O2 swap I got 235 miles which was a mix of city and highway.

We'll be taking a day trip soon. It is about 250 miles from here, so I'm looking forward to see what my highway mileage is.

See XJ specs below.
 
15-16 '01 5" lift 33/12.5 4:56gears Auto

The weird part is get 15-16 in the city, on the highway, wheeling. It doesn't seem to matter where I am driving.
 
I've got 3 different 4.0's, and they all get different mileage.

90 XJ: I've owned this for 16 years, and have kept track of mileage from the beginning. Around town in the summer it got 16 mpg, in the winter with oxygenated fuels, it got 14-15. This is with the 5 spd and stock everything. On the highway when the speed limit was 55, I managed 22 mpg once, and 20-21 mpg occasionally. One summer pulling a trailer in the mtns with the family aboard and 3" lift with 30's, 3.55's, I got 20 mpg. The latest highway mpg commuting to South Denver at 75-85 mph with 3+ lift, 31" tires, and 4.11 gears; good tune up; rebuilt, balanced fuel injectors; Mike Leach/Mopar header with ceramic coating and custom exhaust; home made Cold air intake, I average about 15 mpg. It has 150k miles on it, bad blow by, and one cylinder with bad valves, based on a low compression ratio that wouldn't come up with oil squirted in.

88 MJ: I really haven't driven this all that much. It has a 5 spd, and everything is pretty much stock. At 170k miles, it gets 16-18 mpg regardless of city or highway.

99 WJ: With the distributer less ignition, and a K+N filter, and an auto, it manages close to 20 mpg commuting to S. Denver at 80 mph with the air conditioning on. The air conditioner doesn't seem to make much difference as far as mpg goes. If it hadn't been built by Chrysler, this could have been an exceptional vehicle.

Fred
 
4:56 gears broke in, driving like a bat out of hell, or an a$$hole with a new beamer for the last 15 gallons of gas, 12 mpg.

Top speed with new gears reached, so far, 95 mph :cool:
 
To figure out what gears will be best for your setup, use this formula:

the NEW or DESIRED tire size, divided by the OLD tire size (In my case it was 33 divided by 26).

Now take that #, and multiply it by your CURRENT gear ratio, for me it was 3.55. This netted 4.5057 for me personally, so the best gear ratio available for 33's on my rig is 4.56. This formula works at all times.
 
Skwerly said:
To figure out what gears will be best for your setup, use this formula:

the NEW or DESIRED tire size, divided by the OLD tire size (In my case it was 33 divided by 26).

Now take that #, and multiply it by your CURRENT gear ratio, for me it was 3.55. This netted 4.5057 for me personally, so the best gear ratio available for 33's on my rig is 4.56. This formula works at all times.

Well im sticking with the size tires i have. I have 32 11.50. And im running stock gear ratio. So what numbers should i use then?
 
jeepfreak1020 said:
Well im sticking with the size tires i have. I have 32 11.50. And im running stock gear ratio. So what numbers should i use then?

4.2074074074074074074074074074074 (Based on 32" from 27" tire size)
 
Then you need to decide what you want, a 4.10 will be closer to stock than a 4.56. However if you ever decide to go up to 35's you'll be doing another gear swap. On my automatic equipped 99 XJ I was planning on running 4.56's. I figured it weould be better to be over geared than under, plus I wouldn't have to change anything when going to 35's.
 
When I had my XJ I got 19-20 mpg when I took it to moab and grand junction a few diff. times and around 15 normal city driving. This was in a 88 with 37" mtrs and 4.56 gears
 
DutchVDub said:
Then you need to decide what you want, a 4.10 will be closer to stock than a 4.56. However if you ever decide to go up to 35's you'll be doing another gear swap. On my automatic equipped 99 XJ I was planning on running 4.56's. I figured it weould be better to be over geared than under, plus I wouldn't have to change anything when going to 35's.

Ya thats true, i would rather be over geared.
 
19 MPG city/highway combined.

'90, Auto, 3.55 gears, 235/75/15 tires, high altitude CPS, new exhaust manifold.

Put on 31s to drive over Saxon for Father's day, 12.5 MPG.
 
Well, the 2nd full tank has been consumed on the '96.

This time I put in 14.5 gallons, drove 205 miles = 14.3 MPG. A little worse than the 15 mpg I got last tank, but the misfire condition was much worse toward the end.

I pulled the plugs.... so worn out that they had larger than a .055 gap! I replaced the plugs, wires, cap and rotor today and then went and had a muffler shop replicate a cat-back exhaust. I had 'em copy the Rusty's cat-back design using an 18" glass pack. It sure sounds better anyway.

Then I filled the tank again.

It'll be interesting to see if the tune up and/or the exhaust helps in the MPG results after this tank.

Still gotta do the gears.
 
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Drove from Houston to Central Texas Sunday.

I was surprised to see that I was getting 14 mpg on the highway with cruise control on. I was driving 75 miles per hour and 3000 rpm.

2nd tank was 14 mpg.

3rd tank was 16.8 mpg! This is the best mileage I have had since I started measuring the mpg. This was on the way home. It was dark and got cooler as we drove back to Houston. I drove back at exactly 65 mph and 2400 rpm. I still have a problem, I just have to find it.
 
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