What is the compression ratio of a diesel engine?

[AnastasiaLee]

Diesel engines are not limited by knocking, and their compression ratio generally ranges from 12 to 22. Below is a related introduction: Compression ratio: It indicates the degree to which the gas in the cylinder is compressed when the piston moves from the bottom dead center to the top dead center. The compression ratio is one of the important parameters of an engine. To describe the technical parameters of an engine, one can roughly use the power and torque values. However, there are many factors that affect the output of power and torque, one of which is the engine's compression ratio. Minimum working volume of the cylinder: This refers to the total volume above the piston when the piston is at the top dead center, known as the combustion chamber volume, denoted by Vc. The total volume above the piston when the piston is at the bottom dead center, which is the maximum volume of the cylinder, is called the total cylinder volume, denoted by Va, i.e., ε=Va/Vc.

[DelAshlyn]

I've been driving diesel vehicles for many years. The compression ratio refers to the degree of air compression in the cylinder, which is typically very high in diesel engines, ranging from 15:1 to 23:1. The reason it's so high is that diesel fuel doesn't ignite easily and requires compression to generate high temperatures for spontaneous combustion to start the engine. For example, my old truck has a compression ratio of 18, which gives it strong power and good fuel efficiency compared to gasoline engines with compression ratios around 10. However, if the ratio is too high, the engine noise increases, and the mechanic mentioned that high compression ratios can cause faster wear on piston rings, requiring more frequent oil changes and maintenance. Overall, this design significantly improves diesel engine efficiency, saving a lot on fuel costs for long-distance driving, though it requires a bit more warm-up time when starting.

[VivienneLynn]

My last car repair experience taught me that diesel engines typically have a compression ratio ranging from 15 to 23. The higher the ratio, the more powerful the engine, delivering stronger acceleration. However, there are drawbacks: the noise resembles the rumbling of a tractor, and prolonged use may cause components to loosen due to vibration. Modern new models have more precisely tuned compression ratios, around 22, offering excellent fuel efficiency—I’ve noticed significantly less fuel consumption on the highway. Maintenance-wise, high compression ratios demand better-quality coolant and engine oil to prevent overheating and malfunctions. If you prefer a quieter ride, it’s best to avoid models with excessively high compression ratios when choosing a car.

[Ortiz]

Since childhood, I've loved tinkering with diesel engines, where the compression ratio is crucial, typically ranging between 15:1 to 23:1. Higher compression allows more complete fuel combustion—for instance, a 22:1 ratio can double the engine's power output. But the trade-off is accelerated component wear, requiring extra attention to pistons and gaskets during each maintenance check; otherwise, repairs become prohibitively expensive. When novice drivers ask me, I always advise that a moderate compression ratio best balances performance and safety.