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Need oppinions on more power for the 2.5L

R

RJJR

NAXJA Forum User
Location
Montgomery, Texas
I have a 96' with a 3 inch skyjacker lift and 31" mickey thompson claws. It has the 2.5L w/ 5 speed. Chrysler 8.25 and the stock 4.10's. Its got 180K miles, and runs smoothly, and doesnt burn oil.

My problem is that he jeep is extremely slow and has no guts at all. Ive searched and there is little to no information pertaining to enhancing performance of the little 4 banger.

I have a flowmaster 40 series muffer, and other than that, the driveline is stock.

I just need oppinions and info on other parts that can boost my performance other than regearing, since I already know i need to do this.

Ignition maybe, air intake, 4.0L throttle body, cam regrind, ect.

Id appreciate any helpful information.
 
While you said you do know you need to regear none of the improments are gonna make a damn bit of difference with a 2.5 UNTIL you regear the 4.0 is a bit more forgiving as the torque curve is flatter but the 2.5 just hurts until you put it back where it supposed to be...All of those will help each in little amounts but you wont notice most of them until you regear....
luck
themud
 
I always thought my MJ had enough power to get by with the 2.5, until I got a 97 XJ for a work vehicle. The 4.0 is soooo much faster, more power, everything. But if you don't want to do the swap, check out the heavier flywheel. Will help the 2.5 chug along and have less rpm drop during shifts.
Nate
 
BrettM said:
regear
regear
regear


ditto, gearing will do more than anything else



then see if you need more power. any intake, exhaust, cam type stuff you do will only net small gains, it would probably be better to just swap a 4.0.
Click to expand...
 
Ignition...no, you already have a decent ignition. Intake....maybe, but not much. 4.0 TB....yup, AFTER you make internal mods. Cam.....yes it will give you more HP, but the low end torque will be somewhat reduced. Header....not really unless you make portwork mods...The stock exhaust manifold is really pretty decent.

Regear the beast...4.56... that is absolutely the most bang for the buck. A 2.5 LOVES to run in the 3K rpm range on the road. (this assumes you don't want to run 80 everywhere you go.)

I hung a mad amount of bux in my 2.5.....It was one of those challenge things. The results are pretty amazing...but a stock 4.0 HO definately has more power. And will no doubt live a lot longer, cause I twist the crap out of the 2.5...
 
The best thing you can do is sell it and get a 4.0L high output 91'+ :laugh3:
If you do want to keep the 2.5L, then gear as low as you can go. If you want to upgrade axles then you can go lower than the 4.56 gears that your 8.25 goes down to. 4.56 with 31's should be pretty good and liveable with 33's. If you want to go bigger than 33's then upgrade your axles with dana 44's or hp44/9" or so and then get 5.38 gears or so. I'm going to be running 5.38/5.43 gears in my hp44/9" on my 206K mile 4.0L.

Troy
 
Personally I wouldn't waste time with anything but gears. Go all the way to 4.88's. A YJ with a 4 popper, 33's, and 4.88's barely cuts it. Would have probably gone all the way to 5.38's if it wasn't for the D30. Anyway 4.88's would be just about perfect with 31's.

Bret should remember my dad's YJ. It had 2.25" exhaust on he says the power is better after the pipe got smashed. More torque. The 2.25" is being replaced with 2" this week, we'll see what it's like then.
 
robz95xj said:
A 8.25 will only go to 4.56
Click to expand...
:doh:

Didn't read that much. Ditch the 8.25. I don't think regearing to 4.56's is worth it and he's going to be short on power until he regears.
 
You also have to modify the cross shaft to make the gears work.
 
Lincoln said:
It had 2.25" exhaust on he says the power is better after the pipe got smashed. More torque. The 2.25" is being replaced with 2" this week, we'll see what it's like then.
Click to expand...

try just replacing the tail pipe... its an old hot rodder trick i learned and it worked very well with built-up free-breaathing chevy small blocks.. keep the same muffler but use a "step down" adapter on the outlet side.. 1/4" smaller tail pipe will help with cylinder scavenging because as the exhaust gas cools it's velocity slows... a smaller pipe helps maintain the velocity... my old chevelle gained 23 horses at the rear wheels on a 400+ hp small block.. not sure how much this would help a 2.5L YJ but i'm very interested it this topic as well because thats what my new ty is as well..
 
From some parts catalog reading I've been doing, it appears that the original 2.5L XJs came with a 2" exhaust system, and somewhere around 1987 they changed it to a 2-1/4" system. Dunno if that was for performance, or just to share more parts with the 4.0L engines.

Just order up a tailpipe for an 84 XJ 2.5L
 
The exhaust system was enlarged to get ready for the injected 2.5 to allow for freer breathing for higher fuel flows and FI system.. gearing gearing gearing
 
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