Diesel Engine Compression Ratio
Calculate the high compression ratio typical of diesel engines, which rely on heat from compression rather than a spark plug.
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.
Diesel engines operate at compression ratios between 16:1 and 22:1 — enter your engine specs to calculate the exact ratio for your diesel build.
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.