JE Shelf Piston Size

[carmen78sc]

Are all JE off-the-shelf piston sizes xx.00mm? What I mean is if I buy a set of 98mm, will they measure out to 98.00mm?

With all the Mahle size groups being slightly smaller (e.g. 97.97mm), is it just a matter of finding good condition Nikasil cylinders and having them honed to the right P/C clearance? Would I have to worry about honing through the Nikasil coating, or is it thick enough that a few tenths of a mm won't be an issue?

Tom

[1fastredsc]

Usually after getting the pistons a machiner will match the bore to your piston's exact size because the clearance between the piston and the wall is really small.

[carmen78sc]

I think I understand that part. Let me rephrase my question(s) a little bit - are the shelf JE pistons always bigger than or equal to the biggest size group of equivalent Mahle pistons? (i.e. you can only machine a bore bigger, not smaller to fit) And, if you're machining the bore bigger to match the JE piston and get the right clearance, does one need to worry about machining/honing all the way through the Nikasil plating?

[JeremyD]

Yes and measure measure and measure.

For your piece of mind - the JE pistons I received were VERY accurate. less than .5 grams difference - bores size out to 3 decimal places

The cylinders in the other hand were not, even thouse were straight back from the plater. Measure. AND used cylidners that are rebored also have the opportunity to have some taper and some out of roundness.