I have an '89 XJ, before the High-Output was introduced. I picked up some Edelbrock Shorty Headers to replaced my cracked stock manifold. It turns out that the headers are for the post '91 H.O.'s, and my stock intake won't slide back into place. After some research, I now know why, the manifolds have changed in shape and dimensions. So my thought is, after spending all that cash on the headers, why not convert to an H.O., I have been thinking about it anyhow. What do I need from the H.O. as far as intake manifold, throttle body, injectors, and sensors? Will I need the computer and wiring, basically, what's all involved?  

im in the same boat as you. i have a beat up 1991 cherokee, and got a perfect body of a 1990, i know all the sensors and plugs are differnt, it looks like all wiring and computer, intake, header, sensors, throtle, kickdown, there is so much wireing on this 1990 it scares me, were as the 1991 dont have much at all. so to strip out all the wiring in the 87-90 i dont know what it will take, so if you do it let me know, and if i get to it ill let you know..  

So far I've been told everything, the computer, all the wiring, the head, sensors, etc. I can't find anything online on how to do it or what needs to be done. Maybe we'll be pioneers. I know it can be done though.  

Well after a couple of days of research, this is what I found out. I need everything, everything from the head on up and back to the computer with all the wiring, sensors and all. I've been told by a few people it's not worth it for the extra horse power ($1500-2000), although I wanted to do it for the availability of add-on/bolt-on parts. It has been done, but by truly skilled and qualidied mechanics (which I am not, yet), and even they had a hard time. One of the biggest problems is the wiring in the older XJ's (87-90 in particular) it's a mess and a nightmare with almost double the wiring. Sure, parts will fit, but they won't work. So this has been an expensive lesson for me, but I have a taker on the headers, and after alot of diggin, I've been able to find something that will fit my tired old beast.  

yes the head is diffent to i think... but it is not necc. for converting to the h.o. it can and will be done by one of us  

well there is a diff solution, find a 91-93 with a blown or bad motor and put yours in it, cheap cheap cheap. and only a day worth of work      then you get the h.o  

Well the problem with that is there's nothing wrong with my jeep, or the engine really, the HO only give 13 more HP. I've already put a 4" lift on it and swapped in a 242. Other than the cracked manifold, it workd greats. I found the part that will fit the older renix. So I'm good for now. I do have a spare engine in my parts jeep that I'm holding onto, just incase I get the itch, then I'll swap that one in.  

you said you put in a 242, was your org. a 231? and if it was did you have too put in a driveshaft with the yoke from a 242? please let me know and from what year your 242 is from..  

Yes, I had a 231. I can't remember which Jeep the drive shaft can from. My parts heep is also an '89, Limited though. Everything mathced up, but that might not be the case in you situation.  

You can go to my clubs forums to check out the details on the swap if you're interested. Look up "Project XJ "Un"-Limited"  

kool thanks, even the shifter worked or did you replace that as well, cause the 242 has another setting on it, or did you just leave it be and let alone?  

I swapped the shift lever, and the plate that mounts to the floor. The plate from the 242 is different. A little bit of adjusting with my buddy underneeth, and it was done. It's not a really hard job, and can be done by two guys in about four hours if you have all the tools. (unless you run into problems, ie broken/seized bolts)  

kool thanks