As I understand it, most pistons from the factory are in the hole. If the cylinders are then zero decked, would that bump compression up, down, no difference?


Thanks!

 

If you reduce the area that the cylinder volume is compressed into, you increase compression. So if you make the combustion chamber in the head smaller by milling the head surface, compression increases. If the piston stock, is say 0.050 below the deck of the cylinder and you reduce that by machining the base of the cylinder, lowering it into the case, or mill the top of it ( same effect) and now that 0.050 is only 0.025, you increase the compression.

 

Zero deck would bump the compression if you were in the hole

 

Thank you! That is actually good news for what I'm needing to do.