What happens to the piston during the power stroke?

The power stroke is a critical phase in the operation of an internal combustion engine where the piston performs work. During this stroke, the combustion of the air-fuel mixture occurs within the cylinder, resulting in a rapid increase in temperature and pressure due to the expansion of gases produced by combustion. As these gases expand, they force the piston downward, converting the energy from the combustion process into mechanical work. This movement is essential for driving the crankshaft, which ultimately powers the engine and any connected machinery.

In contrast, during other strokes such as the compression stroke, the piston moves upward to compress the air-fuel mixture, or during the exhaust stroke, the piston moves upward to expel burnt gases. Understanding that during the power stroke the expansion of gases directly leads to the downward movement of the piston is key to grasping how internal combustion engines function efficiently to generate power.