If the engine backfires, the sudden pressure in the intake manifold forces the valve back.

如果发动机回火，进气歧管骤增的压力就迫使阀门向后移动。

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The function of exhaust diffuser is to transform part of momentum energy of exhaust gases from engine into pressure energy to simulate actual exhaust back pressure and environment pressure.

排气扩压器的作用是将发动机排出燃气的部分动能转换成压力能，真实模拟发动机排气反压和环境压力条件。

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But because of reduced injection timing and increased exhaust back pressure, the BSFC of the engine will be increased of 8%.

但由于提前角减小，排气背压增大，发动机燃油消耗率上升8%左右。

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