I have a set of mahle pistons that supposely came out of a high perf m30 motor. I was told they are 10.5:1 compression. They do have dome on top of the piston. Piston have been sitting around for years and have lots of carbon deposit on top.How can I tell visually. part#'s where to find.
thanks guys
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usually on the underside of the crown, quite often you need to remove the rod to see the number properly.

If its high comp it might have come from a euro motor, 3.5's came with a 10:1 comp ratio.

Do you know what the diameter of the crown is? help to work out what motor it came from.

usually on the underside of the crown, quite often you need to remove the rod to see the number properly.

If its high comp it might have come from a euro motor, 3.5's came with a 10:1 comp ratio.

Do you know what the diameter of the crown is? help to work out what motor it came from.


I found these numbers on the inside of the piston skirt, 0031 and 89V7, know what they mean