For a given displacement, how can power be increased?

To increase power for a given displacement, raising the compression ratio is an effective method. The compression ratio refers to the ratio of the maximum cylinder volume when the piston is at the bottom of its stroke to the minimum cylinder volume when the piston is at the top. A higher compression ratio allows for a more efficient combustion process because it increases the pressure and temperature of the air-fuel mixture before ignition. This promotes a more complete and quicker burn of the fuel, leading to greater energy extraction from the combustion process.

Additionally, an increased compression ratio can improve the overall thermal efficiency of the engine, allowing it to produce more power without increasing the size or weight of the engine itself. As a result, this method is frequently utilized in performance-focused engines to enhance their output within the constraints of a particular displacement.

The other options would typically result in a decrease in power. Lowering the compression ratio reduces the efficiency of combustion, shortening the time available for energy release. Decreasing the stroke of the piston limits the engine's ability to draw in air and fuel, which can diminish power. Increasing clearance between the piston and cylinder can lead to loss of compression, adversely affecting engine performance.