Compression Ratio

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

The compression ratio, abbreviated as CR, in an engine is the ratio of the maximum volume to the minimum volume in a cylinder. The equation and calculator below can help find the compression ratio. 

\(\large{ CR = 1 +  \frac{\pi}{4} \; \frac { BORE^2 \; STROKE }{CCV \;+\; HGV \;+\; PVD  }  }\) 

Where:

\(\large{ CR }\) = compression ratio

\(\large{ BORE }\) = bore

\(\large{ CCV }\) = combustion chamber volume

\(\large{ HGV }\) = head gasket volume

\(\large{ PDV }\) = piston deck volume

\(\large{ STROKE }\) = stroke length

Tags: Equations for Engines