Corrected and uncorrected compression ratios calculator

Enter your bore and stroke, the distance from the top of the exhaust port to the top of the barrel, along with the volume (in CC) of the heads combustion chamber to find out what you uncorrected and corrected compression ratio is.

Bore:  mm
Stroke:  mm
Height over exhaust port, top of port to top of barrel  mm
head volume (head cc)  cc
uncorrected  :1
corrected  :1
Note: The calculator does not take into account the stuffing effect of the expansion chamber. The stuffing effect increases the compression when the expansion pipe “comes on song”, in simple terms, this is what gives the engine a powerband. This needs to be taken into account when choosing head volume.