So I have a 98 cherokee 4.0l I was wondering if I put a turbo on it but dont need to change like the rods and stuff and how much psi would be okay on a stock engine

 

I would probably say around 5-8 psi would be fine, possibly higher - these are pretty tough engines. You will need to make sure your fuel system can supply enough fuel and you have a good enough tune to keep it out of detonation.

 

BTW, you may want a look at this AMC build thread for inspiration. It just appeared after I posted my first reply.

https://www.homemadeturbo.com/forced...sx-4-a-121253/

 

In my case, the stock bottom end of a 4.2 (the older variant of the 4.0) is plenty stout for for my pressure levels which are right at 7psi. I have no doubt it could handle more but I would suggest building your system to hang around 8psi for a longer life. Watching lots of YouTube I have noticed that when trying to build massive amounts of power with any engine, its life span is GREATLY diminished. Even a couple psi are totally noticeable and will certainly increase the performance of your Jeep.