bigoltrux77 said:
i guess nobody knows anything...interesting
I suspect as soon as they saw "2.5L" most people lost interest. If you haven't already noticed, the 2.5L is the Rodney Dangerfield of XJ engines -- it doesn't get any respect (except maybe from HossHoffer).
Your question asked what will mate to your AX-5 tranny, so I'll skip the small-block Chevy and 4.3L GM transplants because they won't mate up -- and, as already noted, even with adapters they'll eat the AX-5 for breakfast.
The reason the GM 3.1L and 3.4L engines (rear wheel drive versions ONLY!) can be used is that they are the same small 60-degree block as the older GM 2.8L engine. Jeep bought the 2.8L engine from GM and used it in the XJ from 1984 through 1986.
Therefore, it makes an easy swap using factory (or junkyard) parts. You would need to get your grubby mitts on a set of 2.8L motor mounts and brackets, and you would need to get a set of XJ 2.8L exhaust manifolds (they are not the same as Chevy manifolds).
What else? You didn't state what year your 2.5L is. The Jeep 2.8L was carbureted and used a mechanical fuel pump mounted on the block. So did the '84 and '85 2.5L XJ. In 1986 the XJ 2.5L got throttle body injection and the fuel pump was changed to an electic unit mounted in the gas tank. In 1991 the 2.5L got multi-port injection, which requires a fuel pump that puts out more pressure than the throttle body pump.
Therefore, depending on whether you want to run the 3.4L with an XJ carburetor, aftermarket throttle body injection, or later model Jeep MPFI, you'll probably be faced with having to swap out the fuel pump.
Stryker is running a 3.1L in his MJ, but it replaced a blown 2.8L rather than a 2.5L.