If you're breaking your engine in on the street or racetrack, the high speed incoming air will keep the engine temperature in the normal range.

如果你在马路或赛道上磨合你的发动机，高速进风可以使发动机温度保持在正常范围。

youdao

Valve rotator is an important device to ensure the normal operation of the inlet and exhaust valves of a medium speed diesel engine.

旋阀机构是保证中速柴油机进、气阀正常工作的重要装置。

youdao

The witness said he did not hear any irregular engine noise when the helicopter went past and the height and speed of the craft were normal.

BBC: Colin McRae's neighbour describes helicopter crash