purustussuhe

Purustussuhe is a Finnish term that translates to "compression ratio" in English. It is a fundamental concept in internal combustion engines, referring to 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. Essentially, it indicates how much the air-fuel mixture is compressed before ignition.

A higher purustussuhe generally leads to greater thermal efficiency and increased power output from the engine. This is because compressing the mixture more tightly before combustion causes it to burn hotter and produce more pressure on the piston. However, excessively high compression ratios can lead to engine knocking or detonation, a phenomenon where the fuel ignites prematurely and uncontrollably, potentially damaging the engine.

The optimal purustussuhe for an engine is determined by various factors, including the type of fuel used, the engine design, and performance requirements. Gasoline engines typically have purustussuhte values ranging from 8:1 to 12:1, while diesel engines, which rely on compression ignition, often have much higher ratios, sometimes exceeding 20:1. Engineers carefully select and tune the purustussuhe to balance efficiency, power, and engine longevity.