What is the primary function of piston rings?

The primary function of piston rings is to seal the piston and cylinder wall. This sealing action is crucial for maintaining compression within the combustion chamber, ensuring that the air-fuel mixture does not escape during the combustion process. By creating a tight seal, piston rings help maximize engine efficiency and power output, as well as minimize the amount of oil that can enter the combustion chamber, thereby reducing oil consumption and emissions.

In addition to sealing, piston rings also play a role in heat transfer from the piston to the cylinder wall, but their most critical function is to provide a proper seal to support the engine's operation. This sealing is vital for preventing blow-by, where combustion gases escape past the piston into the crankcase, which would lead to a significant loss of engine efficiency and performance.