Tiivistysastetta

Tiivistysastetta, often translated as compression ratio, is a fundamental parameter in internal combustion engines. It represents the ratio of the volume of the cylinder above the piston at the bottom dead center to the volume above the piston at the top dead center. In simpler terms, it's how much the air-fuel mixture is squeezed before ignition. A higher compression ratio generally leads to a more efficient engine because it allows for more work to be extracted from the combustion process. This is because compressing the mixture more increases its temperature and pressure, resulting in a more powerful explosion when ignited by the spark plug.

However, increasing the compression ratio is not without its drawbacks. A very high compression ratio can lead to a phenomenon called knocking or detonation, where the fuel ignites prematurely and uncontrollably. This can cause significant engine damage. Therefore, engine designers must carefully balance the desire for high efficiency with the need to avoid knocking. The type of fuel used also plays a role; higher octane fuels can withstand higher compression ratios before detonating. Modern engines often employ sophisticated control systems to manage ignition timing and prevent knocking, allowing for higher compression ratios and improved fuel economy and performance.