Mechanical Efficiency (η_m)
Ratio of brake to indicated power. A falling η_m at fixed IMEP is the earliest sign of rising friction (piston rings, bearings, seals).
Mechanical efficiency
88.89%
Friction power
1,500.0kW
Formula, assumptions, and limits
Typical modern slow-speed η_m 0.90–0.92; medium-speed 0.87–0.90. Falling η_m at fixed IMEP = rising friction - early indicator of ring wear or bearing distress.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Brake power | kW | shaft torsionmeter | |
| Indicated power | kW | indicator / IMEP | |
| Mechanical efficiency | - | result | |
| Friction power loss | kW | result |