**Compression Ratio**

Is calculated as follows (fill in the blanks)

Bore = Orig Bore Size + Clearance + Overbore amount

___________ | with | ____________ | clearance on | ____________ | overbore |

Original Bore i.e. 4.360 | piston clear in .000 i.e. .0025 | amt of bore i.e. .030 or .040 | |||

__________ | + | __________ | + | __________ | = | ___________ |

bore |

**Swept Volume in Cubic Centimeters (cc’s)**

Bore 2 X 12.8704 X Stroke 12.8704 = .7854 x 16.387 (# of CC per CI)

_{________________} |
x | 12.8704 | x | _____________ | = | ______________ |

Bore x Bore |
Stroke |
Swept Volume |

_________________ X 12.8704 X _______________ = ________________

Clearance Volume in Cubic Centimeters (cc’s)

Chamber CC | + | Deck Volume | + | Gasket Volume | + | Piston(relief or dome)Volume | = Clearance Volume |

(See "A" below) + or - number

_________ | + | _________ | + | ___________ | + | ____________ | = | ______________ |

chamber cc | deck volume | gasket volume | piston volume +/- | clearance volume |

**"A"** - Deck volume is the amount of additional clearance above the block
and must be calculated just like swept volume; except instead of using stroke length you
use clearance amount.

Bore^{2 } |
x | 12.8704 | x |
____________ | = | _____________ |

i.e. .015 or .025 |

Knowing all these numbers now … you can fill in this formula

Compression Ratio | = | Swept Volume | + | Clearance Volume | / | Clearance Volume |

___________ | = | __________ | + | __________ | / | ________ |

Clearance can be backed into by reversing the formula above to

Clearance volume =Swept Volume / Comp Ratio -1

__________ | __________ | __________ | ||||

Clearance Volume | = | Swept Volume | / | Comp Ratio - 1 |

EXAMPLE

Bore = Orig Bore Size + Clearance + Overbore amount

4.036 | with | .0025 | clearance on | .030 | overbore |

Original Bore i.e. 4.360 | piston clear in .000 i.e. .0025 | amt of bore i.e. .030 or .040 | |||

4.036 | + | .0025 | + | .030 | = | 4.3925 bore |

**Swept Volume in Cubic Centimeters (cc’s)**

Bore ^{2} X 12.8704 X
Stroke
12.8704 = .7854 x 16.387 (# of CC per CI)

_{19.294056} |
x | 12.8704 | x | 3.85 | = | 956.04 cc |

Bore x Bore |
Stroke |
Swept Volume |

Clearance Volume in Cubic Centimeters (cc’s)

Chamber CC | + | Deck Volume | + | Gasket Volume | + | Piston(relief or dome)Volume | = Clearance Volume |

(See "A" below) + or - number

96 | + | 3.73 | + | 11.4 | + | 4.7 | = | 115.83 |

chamber cc | deck volume | gasket volume | piston volume +/- | clearance volume |

**"A"** - Deck volume is the amount of additional clearance above the block
and must be calculated just like swept volume; except instead of using stroke length you
use clearance amount.

19.294056 | x | 12.8704 | x |
.015 | = | 3.73 |

i.e. .015 or .025 |

Knowing all these numbers now … you can fill in this formula

Compression Ratio | = | Swept Volume | + | Clearance Volume | / | Clearance Volume |

9.25 | = | 956.04 | + | 115.83 | / | 115.83 |

Clearance can be backed into by reversing the formula above to

Clearance volume =Swept Volume / Comp Ratio -1

115.83 | = | 956.04 | / | 8.25 |

Clearance Volume | = | Swept Volume | / | Comp Ratio - 1 |