2.5L Power issues (what a surprise)

I've got an 84 XJ that i got for $500. I put a budget lift on it, some 32"s, welded the rear carrier, and a few other slight mods.

I knew i would want more power, and i had planned on doing a swap to a 4.0, but after doing some homework, i think its a little more than i want to do. It does decent now, but just lacks the power to get up the real steep inclines, and rocks (being carburated doesnt help either).

I've considered re-gearing (its strictly a trail rig so i could go really low), but will that really do me any good, or will i always be struggling for power? Should i put the money in re-gearing, or would i be better off just dropping some money on an XJ with the 4.0 already in it, and then swapping the tires and lift?

Any one out there successfully running with a 2.5 that can give me some advice?

Well, you added about 4 inches to your tires. That would change your final gear ratio drastically. If you regeared lower then you would get back to stock performance. Was it peppy enough stock? I had a friend with a 2.5 in a wrangler, I thought he was crazy with 33's and a 2.5, but geared properly nothing stopped him.

The best mod at this point will be 4.88 gears. It is possible to wake up a 2.5. I have one that screams...but it ain't cheap...and it still won't have the power of a healthy 4.0...but yes it can be done...a header, aftermarket intake and weber carb will go a long ways...and the weber is not nearly as sensitive to off camber sections as the weenie carter that is stock.

My 2.5 does great for the trail. I got rid of all the vac. lines down to three. It runs alot better than with all the vac. lines. I have 31" tires and it does what I need it to do. Regear or if you know the engine pretty good than I would just build it up. Very simple engine. Kim.

What kind of RPM range does the jeep 2.5L have? I had a 91 Toyota with the 115HP 22RE 4 Clylinder. It was a 5-speed with 33s. I ran a 5.29 gear with the 33s and it was great. It did turn some RPM on the highway but it was very driveable on and off road. It took a long time, a looonnggggg time but it would peg the speedo(100) eventually lol.

Gear it as low as you can..if you do not have overdrive it would suck though.

I couldn't tell you the RPM range...no tach. Up to 100 though? Thats pretty impressive. I'm pretty sure the jeep would have parts flying off before it ever made it to 100.

Thanks for the imput guys, I've got a spring break run coming up in a few weeks, but after that I think I will go to the 4.88's and hopefully sometime in the near future get enough $$ for a new carb.

I have an '85 with a 2.5 and 32 in. tires. It has 4.56 gears in the axles with a ratchet locker in the rear. This setup has really suprised me. I asked a few people about going to 4.88s but they all told me that in the D30 front axle the pinion gear stars getting too small and becomes a strength issue.

The D-30 is stronger than some give credit for...if you have a manual trans and go crazy with the clutch you can break it...if you have an auto trans you most likely won't...I have 4.88 gears....wish I could get 5.xxx+ gears without an axle swap...The motor when stock redlines at around 5,500 rpm.

With the gears and 33's, I cruise at 3,000rpm...it loves it...with the mods I have the motor pulls strongly to 7k plus...DO NOT try that with a stock motor.
I dont have the kahonas to see how fast it will go...60mph is plenty fast...and I get 18+ mpg with it.

85xjwoody said:

My 2.5 does great for the trail. I got rid of all the vac. lines down to three. It runs alot better than with all the vac. lines. I have 31" tires and it does what I need it to do. Regear or if you know the engine pretty good than I would just build it up. Very simple engine. Kim.

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what vac lines did you pull? thing looks like a speghetti mess under the hood i've been meaning to do that but don't know whats important and whats not.

emtpiston said:

what vac lines did you pull? thing looks like a speghetti mess under the hood i've been meaning to do that but don't know whats important and whats not.

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I am running ported vac to my distributor, manifold vac to my 4wd, and manifold vac to my heater controls. Everything else is plugged off. If you do this you will have to adjust your timing by turning the distributor.

Kim.