I have an 89 YJ with a 4 banger, and I am having trouble figuring out what I can do to get some more power. I am running 31" tires so i notice a bit of power loss, especially in the upper gears. I plan to put on a cat back exhaust system. Besides that what else can I do? Rock it makes aftermarket intakes, throttle bodies and spacers for the 2.5L, but not for my 89. I checked headers, but I am having a hard time finding those for my car as well. ANY ideas/tips would be much appreciated...Thanks

http://www.cris.com/~jman/jeepmods.html

This works on pretty much any inline jeep engine... try it out

erm, fuel injected inlines that is....

Um, all YJ 2.5L's are EFI. Earlier ones are TBI though. Personally, I found no gain what so ever when I removed those so called restrictors. The one in the airbox is more of a venturi which causes a vacuum that pulls the crank case fumes back into the engine.

Cat-back exhaust, headers, K&N conical filter, +8mm spark plug wires... Lots of stuff to consider. But you won't be able to do a 4.0L TB since you have TBI. You might be able to do a .450 duration cam. Hard to find the .440's anymore.

To put in a conical K&N air filter what do you suggest I do since there is no replacement air tubes that I can find for the 89...everything is 91-95.

Borla makes headers for the 89 2.5L. I put them on my 89 YJ and i love 'em. that EGR valve is nasty, though. I had to take it to the muffler shop and have 'em bend it. I also put in a K&N panel filter and i noticed a difference.
This weekend I just got done with removing the mechanical fan and putting in an electric and i've noticed a little difference.

it's all step by step.

</font><blockquote><font size="1" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">quote:</font><hr /><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">Originally posted by Flouris:
<strong>To put in a conical K&N air filter what do you suggest I do since there is no replacement air tubes that I can find for the 89...everything is 91-95.</strong></font><hr /></blockquote><font size="2" face="Verdana, Tahoma, Arial, Helv, Helvetica, Sans">Well, you might be able to use one for a 91+. SOme guy's are using Honda Civic air tubes on their Jeeps. Since I wanted one way before there was even a market, I custom built one. You might have to resort to a custom one. You could even use black ABC tubes to make one.

What axle gears did you change to when you went with the bigger than stock size tires?

SD

I actually didn't change any gearing on my truck...my tires are not massively oversized...only 31" but i noticed a small differnece in acceleration and power.

31's are about the limit on a 2.5L manual before you start to feel a loss in performance. I ran 32's for several years with stock gears. You probably won't need too much to regain the power you lost. After driving around with 32's, I thought 31's felt stock. I'd go with the basic's. Decent exhaust, perhaps performance cat, conical air filter. Maybe even an electric fan. By moving the fan to a dedicated electric motor, it leaves the engine to power the Jeep.