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What compression ratios are typical in diesel engines?
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diesel engine
Diesel engine equipped with a precombustion chamber.
Diesel engines are typically constructed with compression ratios in the range of 14:1 to 22:1.1
These high ratios are a defining feature of the diesel engine, allowing it to heat the air charge within the cylinder to temperatures exceeding 526 °C (979 °F). This process, known as compression-ignition, enables the fuel to spontaneously ignite upon injection without the need for an electric spark. Because diesel engines compress only air rather than an air-fuel mixture, they avoid the preignition issues that limit compression ratios in spark-ignition engines, allowing for higher theoretical cycle efficiencies.1