Modified 100mm Porsche 964 Nikasils - Progress

[hydra]

I guess I should have asked, what is the difference in cylinder height between the 964 cylinders and the stock T4 cylinders? I need to figure out the overall deck height with these cylinders...

[Wally]

I guess I should have asked, what is the difference in cylinder height between the 964 cylinders and the stock T4 cylinders?

The height from head sealing plane to the plane that lies against the case (still with me?) is a LOT shorter with the 964 barrels.
However, the part of the cylinder that goes into the case is considerable longer... Must also be, because stroke in a 964 is 76mm, but with a piston that has a much higher pin height and smaller skirt.
However, even then, the skirt of the 964 piston will extend quite a lot beyond the end of the cylinder at Bottom Dead Point. Don;t worry about that as porsche didn;t either, but thats probably the reason it is wise not to stroke more then that 76mm.
Even with 76mm stroke, you will need thick spacers (the 964 case is obviously wider then a T4. WBX is closer in width... Mine were 10mm iirc. With stock 2 ltr (71mm) stroke, less spacer is needed and the piston extends less. Probably better and esier to build.
BTW and I think I have mentioned this before: there is a difference in piston bottom thickness between early 964 P-pistons (P=pressed=forged) and later (>'90) 100mm pistons. The early cylinders also had flat wall tops and thick bottom pistons, while the later cylinders had the sealing groove and some of those pistons had thinner bottoms... so beware to check out what you have before starting that mill...
Good luck!