Hey Folks,

Looking for some advice on the cylinders in my F20C. This is my first build and I intend to build an F24C stroker using a K24 crank and some aftermarket rods/pistons. I don't yet know if there is a capable machine shop in Winnipeg that has experience with FRM cylinders. I was hoping that I could use the block as-is but I'm not sure given the measurements that I have. Here what I've got:

Cylinder - Top X - Top Y - Mid X - Mid Y - Bottom X - Bottom Y - Taper X - Taper Y - Diff Top - Diff Mid - Diff Bot

1_______87.04__87.08__87.04__87.07__87.03___87.03_ ____-0.01____-0.05___0.04_____0.03___0

2_______87.03__87.09__87.04__87.07__87.03___87.06_ ____0_______-0.03___0.06_____0.03___0.03

3_______87.06__87.09__87.05__87.08__87.04___87.05_ ____-0.02____-0.04___0.03_____0.03___0.01

4_______87.04__87.10__87.04__87.08__87.04___87.06_ ____0_______-0.04___0.06_____0.04___0.02

I know that's a bit difficult to read. But it seems as though the cylinders are within spec (albeit on the edge of it). But the service manual doesn't say anything about cylinders being out-of-round. One cylinder is .06mm longer in one dimension. Is that a problem? THe motor was burning oil when I had pulled it but I'm not entirely sure from where. I'm open to any thoughts and opinions, or if anyone happens to know of a shop in Winnipeg that has done FRM cylinders (I have some head machining I'd be happy to give them, too).

 

The sleeves may be within factory spec for diameter to run, but for a good ring seal the cylinders should be worked over by a competent shop. FRM cylinders can be cut and honed like anything else. The honing process is different than iron sleeves. They need to be honed slower than iron and they need a finer honing stone. I don't remember the specs off hand but they are on the interweb and service manual. Also Porsche has used the same sleeves for many years so any shop familiar with Porsche should be good.