The older 4.0L had 177 hp while the HO version had 190 hp. Well, the XJ got 190 hp, the YJ got 180 hp due to header differences, if I recall correctly.The 4.0L comes in 3 different flavors, the early (pre '91) era 4.0L, the 4.0L HO version, and the current version found in the TJ. For the HO version, the factory updated the design of the intake, cylinder head, camshaft, exhaust, and EFI. The release of the TJ saw more improvements to the 4.0L, but these engines are still relatively scarce and expensive in wreckers. A great deal was found on a very fresh '93 4.0L, which was used for the core of this project. Any 4.0L block would work, though.
They use a different fuel injection system. The newer '91 and up (?) MPI system is better than the older one.Originally posted by Throttle:
I've got an XJ the normal 4L not the HO.. I've heard that the cam is different, along with the computer? What else?