NickBranch

I have a 89 xj 4.0straight 6 non high output..I bought a 98 xj 4.0 straight 6 high output.. I was told that the wiring harnesses are different and if I was to put the high output in it would idle at 5000rpms..is this true and is there anything I can do besides rewiring my whole jeep??

XJ Stryker

Nope you will need everything from donor jeep.

cruiser54

No you don't.


XJ Cherokee and ZJ Grand Cherokee 4.0L engine blocks interchange.

2000+ TJ Wrangler and WJ Grand Cherokee 4.0L engine blocks interchange.

XJ/ZJ blocks and 2000+ TJ/WJ blocks do not interchange without significant modifications. (1997-1999 4.0L TJ Wrangler blocks will interchange in XJ/ZJ and visa-versa).

TJ/WJ 4.0L Engine blocks underwent clean sheet design changes effective in the 1999 WJ Grand and 2000 TJ Wrangler. These blocks are not interchangeable with XJ/ZJ engine blocks. The reason is motor mount bolt holes and belt driven accessory mounting bolt holes are in different locations, or not present at all, TJ/WJ vs. XJ/ZJ.

Worst case scenario is you have to move your coolant temp sender to the thermostat housing on the 98 engine.

Use your Renix flywheel/flexplate, valve cover, distributor and manifolds. Be sure to use an intake/exhaust gasket for the 88. I have done this swap more than a few times.

XJ Stryker

I was talking about the wiring and ecm

XJ Stryker

Its all good if i am wrong but i would assume if you are going to a newer engine you would want the OBDII capabilities and what not.

cruiser54

No. Not necessary and a monumental amount of work for the average guy.

cruiser54

The engines themselves are not that much different. This whole HO crap is pretty much just that. A great marketing scam by Chrysler. 8 whole horsepower, all at the top end, that was predominantly the result of an exhaust manifold change and a 58mm throttle body vs a 52mm throttle body. An HO made no more torque than a Renix.

NickBranch

Awesome that just made my project that much easier!! I'll be slapping that bad boy in within the next few days I'll be sure to post pics!! Thanks again!!

cruiser54

Any questions, post them up.