Compression Check: Description and Operation

COMPRESSION





Piston engines should squeeze the intake fuel/air mixture to about 1/8 of its original volume before igniting it near the top of the piston compression stroke. The rapidly burning mixture creates pressure on the piston top, providing engine power.

The combustion chamber should be tightly sealed during the compression and power strokes. Poor sealing of intake or exhaust valves or leakage between the piston rings and cylinder walls will cause loss of power and economy. Use of a compression gauge is one quick way to check for leakage.