Compression Ratio Calculator
Calculate engine compression ratio from cylinder volume and combustion chamber volume.
Compression Ratio
Compression ratio compares total cylinder volume to combustion chamber volume.
Compression Ratio = (Swept Volume + Chamber Volume) / Chamber Volume
Where:
- Swept volume = the volume displaced by the piston (from BDC to TDC)
- Chamber volume = combustion chamber + head gasket + piston dish (or minus dome)
Typical compression ratios:
- Naturally aspirated gas: 9:1 to 13:1
- Turbocharged gas: 8:1 to 10:1
- Diesel: 14:1 to 25:1
- High-performance NA: 12:1 to 14:1
Effects of higher compression:
- More power and efficiency
- Requires higher octane fuel
- Higher stress on engine components
- Risk of detonation/knock if too high