Mean Piston Speed
Cm = 2·s·N/60. Slow-speed engines 7–9 m/s; medium-speed 9–11 m/s; high-speed 12–16 m/s. Ring-reliability ceiling ≈ 10 m/s.
Mean piston speed Cm
8.75m/s
Formula, assumptions, and limits
Max safe Cm is mostly set by cylinder-liner cooling and ring-wear rate. Long-stroke slow-speeds keep Cm low (8–9 m/s) while maintaining high BMEP through large bore.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Stroke | mm (÷1000 for m) | engine spec | |
| rpm | rpm | tachometer | |
| Mean piston speed | m/s | result |