Static Compression Ratio Calculator

Definitions:

Your engine's static compression ratio is easily calculated if you know six measurements or volumes:

 Bore-- The diameter of the cylinder bore Stroke-- The distance the piston travels in the cylinder Deck Height-- The distance between the top of the cylinder bore and the top of the piston, when the piston is at TDC (Top Dead Center, or at its highest position Compressed thickness of the head gasket-- Usually 0.040", but varies with gasket manufacturer and application Piston top volume-- If the piston is dished, domed, or dimpled, that has an affect on compression ratio. Combustion chamber volume-- How much open space is in the head above the cylinder

Static Compression Ratio Calculator

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If you want to take the formulas with you and put them in your tool box, here they are. 16.387 is a number than converts cubic inches to cc's.

 Displacement  = (Bore ÷ 2)2  x  3.14  x  Stroke  x  16.387 Head Gasket space  = (Bore ÷ 2)2  x  3.14  x  Gasket thickness  x  16.387064 Deck Height space  = (Bore ÷ 2)2  x  3.14  x  Deck Height  x  16.387064 Compressed Volume  = Head Gasket space  +  Deck Height space  +   Piston Top volume  +  Combustion chamber volume Uncompressed Volume  = Compressed Volume  +  Displacement Compression Ratio  = Uncompressed volume  ÷  Compressed volume