The final step came when steam was introduced into the cylinder to drive the piston backward as well as forward, thereby increasing the speed of the engine and cutting its fuel consumption.

最后一步是将蒸汽引入气缸，使得活塞前后推动，从而提高了发动机的速度，降低了燃料消耗。

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In a diesel engine, there is no spark plug. Instead, diesel fuel is injected into the cylinder, and the heat and pressure of the compression stroke cause the fuel to ignite.

柴油发动机内没有火花塞，取而代之的是将柴油喷入发动机气缸，然后压缩冲程在高温高压下引起燃料点火。

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To boost fuel efficiency more diesel engines are popping up, as well as improved four-cylinder engines.

为了提高燃料效率，更多的柴油发动机和改良的四缸发动机应运而生。

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When powered by gasoline, the C-MAX Energi uses the all-new 2.0-liter Atkinson-cycle four-cylinder engine - powerful and fuel efficient and among the most advanced non-turbocharged four-cylinder powertrains Ford has ever offered.

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As with the Optima, the Regal offers a choice of two direct fuel-injected four-cylinder engines.

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The engines do away with expensive cylinder heads where fuel combustion takes place.

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