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Compression Ratio

The ratio of total cylinder volume at bottom dead center to volume at top dead center.

Definition

Higher compression improves thermal efficiency but limits boost and fuel octane tolerance.

Turbo engines often run lower static compression than naturally aspirated counterparts.

Related terms

  • PistonA cylindrical component that moves up and down inside the cylinder, transferring
  • CrankshaftThe main rotating shaft that converts reciprocating piston motion into rotationa
  • CamshaftA shaft with lobes that open and close intake and exhaust valves at precise timi
  • Cylinder HeadThe top section of the engine housing valves, ports, and often the combustion ch
  • Engine BlockThe main structural casting that houses cylinders, crankshaft bearings, and ofte
  • ValvetrainThe assembly of valves, springs, retainers, rockers, and camshaft that controls

Category: Engine · Updated August 31, 2026