GM-GMC: gmc 6.5 turbo diesel, turbo diesel, compression ratio

Question
Hi could you tell me how much i need to mill off the top of my pistons to take the compression ratio down from 22.1 to 18.1.Thanks in advance for any help or tips you can give.

Answer
About 0.010 inches for each point drop in compression ratio.

The pistons are marginal in GM 6.2/6.5 diesels.  Cutting metal from them may not be the best way to accomplish the desired 18:1 compression ratio.

Aftermarket companies offer 18:1 pistons and they may provide better service than machining the OEM pistons.