What does the term "compression ratio" indicate in an engine?

The term "compression ratio" specifically refers to the ratio of maximum to minimum volume within the combustion chamber of an engine. This is a critical parameter as it influences the engine's efficiency and power output. In simple terms, it measures how much the fuel-air mixture is compressed before ignition. A higher compression ratio generally allows for more power and efficiency because the air-fuel mixture is compressed more, leading to a more powerful combustion event.

Understanding the compression ratio helps technicians assess engine performance, optimize fuel choice, and evaluate how modifications might affect engine power and efficiency. This parameter is fundamental to the design of internal combustion engines and has a direct impact on their operational characteristics.