1. the maximum engine speed
a maximum achievable engine speed is the highest rated engine speed. Usually the engine tachometer, a red scale start rotational speed is represented, but not the engine maximum speed achievable. The average value of the four-stroke engine speed is now: idle 600 to 800 rev / min, as the maximum engine speed, typically between 5000 to 6500 rev / min. Highest rated car speed can reach staggering 12,000 rev / min, or even higher. However, generally speaking, the engine speed level rising trend.