The middle ring on a 4 cycle gas engine piston is known as what?

In a four-stroke gas engine, the middle ring on the piston serves a critical function related to combustion efficiency and engine performance. This ring is often referred to as the compression ring because its primary purpose is to maintain compression within the combustion chamber. When the piston moves upward during the compression stroke, the compression ring helps to seal the gap between the piston and the cylinder wall, preventing the escape of combustion gases and ensuring maximum pressure builds up for the power stroke.

In addition to its role in sealing, the compression ring can also help scrape away any oil that might get past the oil control ring, which is located below it. This dual function enhances the overall efficiency of the engine by promoting effective combustion and minimizing oil consumption. Being essential for proper sealing and effective power generation, the compression ring is a key component in optimizing engine performance and durability.