High Compression Race Engine Ratio
Calculate compression ratio for a high-performance race build with a large bore, long stroke, and minimal clearance volume.
How to use this tool
- Enter the cylinder bore diameter and stroke length in millimeters.
- Enter the combustion chamber (clearance) volume in cc from the cylinder head specs.
- The calculator returns swept volume and compression ratio.
Race engines often target 12:1 or higher compression — enter your bore, stroke, and clearance volume to confirm you hit your target ratio.
Frequently asked questions
- What is compression ratio?
- Compression ratio is the ratio of the cylinder volume at bottom dead center to the volume at top dead center. Higher ratios increase thermal efficiency but require higher-octane fuel.
- What compression ratio is best?
- Most naturally aspirated gasoline engines run 9:1 to 12:1. High-performance engines reach 13:1+. Diesel engines typically use 14:1 to 25:1 for compression ignition.