Just wanted to see

[jimoshel]

what I could do. These tricks won't work for normal driving, but like I said. Just wanted to see what I could do.1987 MJ, 2.5, AX4, 2wd. First I set it up the way I normally drive. Jack, spare tire, tool box, tires inflated at 32psi. 85octane reg gas. Made run on Interstate at 75mph. Mileage was 20.5 mpg. Next emptied truck of all non essentials, spare tire, all tools, passenger seat, tail gate etc.. Could not go on Interstate at the speed I was going to run so stayed on frontage rd.front tires at 45psi, rear tires 42psi. I determined that these pressures gave the best footprint. Cleaned and set plugs to .040in, Mobil 1 Synthetic 5-30wt. Installed fuel-air ratio meter. I made several runs but only showing the best one. After a couple miles quit watching the tach and only kept an eye on the AF meter. 35mph got 29.9 mpg. Just going to sit back now and see all the responses claiming their 2012 5.0cc road monster gets 150 mpg at 100mph. :yes:

[86FUBAR]

:hmm: So why don't you go back out on the freeway and run it again at 75 mph and then see what you get with all the "upgrades" that you did to it , at least then we would be comparing apples to apples instead of apples to oranges.

[jimoshel]

Good point. At the time I just wanted to see what was the best i could do. Period. Thought about the highway at 75 but got sidetracked. Going to do it later this afternoon. We'll see.

[Paul Bruchal]

I can't wait! :popcorn:

[1974CJ5]

I basically have the exact same truck, I'm not sure what gear you are running but mine is 3.55. I only run regular, I run havoline 10w30. I drive 10 miles backboards and city, and then 15 miles hwy every single day and back again. I average 25mpg in the summer, 27 mpg winter (ac?). This is with the spare the jack, a gallon of coolant, at least one quart of oil, bed tool bow with a bunch a crap in it. A big fuse kit. Jumper cables, and a lot of other stuff that is required when you drive an 87 model truck as many of these items are consumed on a daily basis. This is just my experience w/ my mj. If your truck has 3.73 gears your mpg sounds about right, from what I understand.

[mvusse]

1987 2.5, AX4 3.55 gears, 4wd, fiberglass cap, P235/75R15 tires at 35psi.

 

Last May I had to go to Chicago, so I did a test. On the way there I filled up just before getting on the turnpike and ran 75mph for 320 miles. Averaged 19mpg.

 

On the way home I took secondary highways going 60mpg. Averaged 27 mpg.

 

 

Decided I needed a 5th gear, so I swapped out the AX4 for an AX5, left the 3.55 gears in the axles and went on a trip to Detroit. 60 mph there I still averaged 27mpg. 75mph on the way home I averaged 24mpg.

[airspeed]

My stock 88 2.5, AX4, 4X4, no AC, SWB, weights 3280 lbs on the scale.

 

In mixed driving to work, 19 miles and 12 stoplights I can get a consistent 21-22 mpg. On a slow highway drive 55-65 I can get 23-24mpg. I believe the high altitude in Colorado takes a toll on the mileage. If I get on I25 and join the race at 75-80mph my mileage drops to about 20mpg.

 

Every time I go to sea level and rent a car I can't believe the power. I would bet the 2.5 at sea level is a decent little motor, up here it is just not quite enough...

[carnuck]

in '02 I took my stock '86 with 2.5, ax-5, NP207 with 4.10 gears and 235/75/15 to Ouray and back with 3 adults, canopy and a load of spare parts, tools, camping gear (rolled over the scale at 6,000lbs with a nearly full tank of gas) and 3 spare tires (2 stacked on the spare holder underneath. We used them all!)

Averaged 17 in the mountains and 22 on the flats. (had clutch slave troubles too) It liked 85 octane better than anything higher (LOST power with a tank of hi-test. WTF?)

[TylerJY]

I get an average of 12/13 8)

 

33's, and 4.88's with the 4.0l HO and AW4