Originally Posted by
captain america
Hi Monty. The P5XL crankcase I plan to use is actually the bare aluminum one, not the newer black one. I got it off e-Bay because my regular P5X case had a broken back-plate screw shaft stuck in the block and that was the closest replacement I could find on short notice.
The reason that I had some hesitation is that I noticed that the back-plate on the P5X has a couple of "dents" in it on either side of the channel where the bottom of the piston sits, whereas the same part on the XL did not, and it then dawned on me that the inside of the engine block was probably channeled differently between the P5X and P5Xs... Hence my wondering if the old P5X sleeve/piston/crankshaft would work or create some sort of power-robbing turbulence.
the only difference is the buttplate , the round one gives more low end torque through less case volume , try them both for yourself and you will see what you like
