What does the engine's compression ratio refer to?

The engine's compression ratio is defined as the ratio of the maximum volume of the combustion chamber when the piston is at the bottom of its stroke (Bottom Dead Center) to the minimum volume of the combustion chamber when the piston is at the top of its stroke (Top Dead Center). This ratio is crucial because it directly affects the efficiency and power output of the engine. A higher compression ratio typically leads to more power and better fuel efficiency, as it allows for more complete combustion of the air-fuel mixture.

In terms of the function of an engine, the compression ratio influences how much air-fuel mixture is compressed before ignition. This compression affects the thermal efficiency of the engine and its ability to produce power. Optimizing the compression ratio is important for performance while also considering factors like fuel type and engine design. Understanding this concept is essential for anyone studying engine mechanics and design, as it plays a pivotal role in how an engine operates and performs.