I6 for I6...yikes!

My buddy blew up the engine in his 95 cherokee last night. I haven't gotten to see it, but I think he blew a rod- there is a giant hole in the bottom of it! It had 220 k's on it, and he was dirivng home- and boom! Anyhow, I have a spare I6 from an 87 xj, and whas wondering how hard it wuold be to do the swap. Both are automatics, and I would think that the engine would just bolt right up...but I don't know. Are there any parts off of his engine(the 94 I6) that would be better than the ones on the 87's, and would bolt right on? Anyone have any thoughts, comments, and some suggestions (help)!

Thanx!
CODEMAN

They are basically the same block. I would try to use only the bottom end as the newer 6 has the HO head.The newer 6 also uses the MPI, the older 6 uses the Renix system. It would just make a much easier swap to move over as much as possable. It would be a good idea to have good look at the block.
Once you have it torn down, it would be just a few more steps to rebuild it or at least "freshen" it up.

MPI, Renix- fuel injectors?? Sorry not to familiar with my engines YET.

Codeman said:

MPI, Renix- fuel injectors?? Sorry not to familiar with my engines YET.

Click to expand...

Before Jeep was owned by Chrysler, they used a engine control system jointly developed by Renault and Bendix, commonly nicknamed the "Renix" system.

Once Chryco took over, and the HO engine arrived, a system using Chrysler designed parts replaced the Renix system. Virtually none of the sensors and controls of the Renix system are the same as that on the Chryco system, so mixing and matching parts from the two systems is not possible.

If it were MY XJ, I would put the short block from the new engine, mated with the head and Renix control system of the old (blown) engine, into the vehicle.

I vote with AZJeff. To put a Renix era engine whole into a later model would involve substantial wiring harness changes. The control units are located in different places, all the sensors are different, even to the point of being reversed in polarity, everything is wired differently, and you'd even have to swap instrument clusters and speedo drives, because the later one is electronic and the gauge sensors are also reversed in polarity. If you had a whole donor vehicle, complete with wiring and all the other bits, it might be worth doing, but otherwise it's likely to be a huge headache

AZJeff and Matthew are correct. Both systems are MPI (multi-port injection) but they are not compatible. Also, the ports are set higher on the head for the '95 HO engine so trying to mate the manifords to the '87 head would require modifications.

Best approach is to pull the blown engine, swap the head onto the '87 engine, then install as if it were a '95 engine.