Power band
（重定向自Powerband）
![A diagram comparing the power and torque of a](/Images/godic/202502/04/Powerband1025.gif")
![turning moment diagram for a four stroke internal combustion engine
A) intake
B) compression
C) expansion
D) exhaust
α) time average engine](/Images/godic/202502/04/Diagramma_di_coppia_motrice_motore_monocilindrico.svg1025.png")
The power band of an engine or electric motor refers to the range of operating speeds under which the engine or motor is able to operate efficiently. While engines and motors have a large range of operating speeds, the power band is usually a much smaller range of engine speed, only half or less of the total engine speed range (electric motors are an exception – see Electric Motors below).