To be more technical, in the diagram the 1-2 curve shows the compression stroke in which pressure (y-axis) rises and volume (x-axis) drops as the piston does work on the gas, squeezing it.

Most piston manufacturers list the volume of their pistons. See All 4 Photos Whether the piston is above deck or in the hole at top dead center also affects compression ratio.

You can learn how to calculate piston compression height with this easy guide. Click here for more details or check out the December 2012 issue of Hot Rod Magazine.

The patent diagram appears to show a high and low position currently, not a variable height. The car starts off with the piston in the high position. When the turbo begins injecting pressurized ...

Key to Porsche’s six-stroke engine is an eccentric crankshaft mechanism that changes the piston’s stroke, giving each cylinder two top and two bottom dead centers and three stroke lengths.

It explodes, expands and pushes the piston down. Get the timing or compression wrong and the fuel might preignite, exerting destructive pressure on the piston while it’s still moving upward.

Most piston manufacturers list the volume of their pistons. See All 4 Photos Whether the piston is above deck or in the hole at top dead center also affects compression ratio.

Rounding out the rotating assembly will be 6.385-inch rods and pistons with a 1.270-inch compression height and 18cc dome. We’re using a seasoned block that required a bit of surface ...