What does this P&C measurement mean?
 

I am trying to order my rebuild kit for my 3.2L ('87), turbo'd 911 but don't know what piston ring size to order.

Originally, I thought the engine simply had 930 P&C's on it but my friend I bought it from said it has 3.4L Mahles P&C's and possibly explains the weird measurements I am getting.

So, the 930 uses 97mm cylinders and the stock 3.2L uses 95mm cylinders, correct?

I am getting an average 97.86mm using a digital dial caliper using ID jaws. I know dial calipers are not that accurate (I come from aviation and they are not allowed for critical measuring) but 0.030" (converting to SAE) off, I really don't think it could be since measuring my crank journals have been within specs.

Where do I find the Mahle 3.4L P&C's specs for a C3.2L engine at? Couldn't find on the interwebs....

Talk to Don at EBS.

3.4 Mahles are 98mm. Anyone who sells Mahle should be able to source rings for you.

Yeah, it must be 98mm. That would only be .005" off from my measurement - accounting for the caliper error. I'll check with Wayne before Don; it's only fair to our host.

Just to be careful, measure the ring thickness of each ring to make sure you will be getting the right ones if there are more than one type of ring setup.

Yeah, I was told that when calling around. Thanks for the info and good catch.