The compression ratio compares the maximum cylinder volume at bottom dead center to the minimum clearance volume at top dead center. A higher ratio extracts more mechanical energy from the air-fuel mixture, improving thermal efficiency and power output. High-compression engines require higher-octane fuel to prevent premature ignition of the charge.
We milled the cylinder head to bump the compression ratio up to 11 to 1 for the new race build.
Also heard as
- CR
Related terms
Compression
The phase in an internal combustion engine where the piston squeezes the air-fuel mixture.
Bottom dead center
The lowest point of a piston's travel within its cylinder during an engine cycle.
Top dead center
The exact point in engine rotation where a piston reaches its highest position in the cylinder.
Knock
An abnormal and damaging combustion event where the air-fuel mixture self-ignites prematurely.