Rod Ratio Calculator

Analyze connecting rod to stroke ratio and its effects.

inches
Center to center distance
inches
inches
For bore/stroke ratio

Rod Ratio Guidelines

RatioCategoryCharacteristics
< 1.5Short RodMore torque, higher side load
1.5-1.65Common StreetBalanced performance
1.65-1.8PerformanceGood all-around
1.8-2.0High PerformanceBetter ring seal, less friction
> 2.0Race/High RevBest for high RPM

Rod Ratio Effects

  • Longer rod ratio - Less side loading, better ring seal, higher RPM potential
  • Shorter rod ratio - More leverage at TDC, often more low-end torque
  • Piston dwell - Longer ratio = more dwell time at TDC for combustion
  • Piston speed - Longer ratio = more consistent piston speed through stroke