Compression Ratio Programme

This programmme calculates the Trapped Compression Ratio for a Two-Stroke Engine.

In a two-stroke engine it is standard practice to calculate compression ratio based on the trapped swept volume i.e the swept volume after the exhaust port has closed. The calculated compression ratio is usually referred to as the "trapped compression ratio".

For four-stroke engines it is standard practice to calculate compression ratio based on the full swept volume of the engine. This is often referred to as "geometric compression ratio" but is also known as the "static compression ratio". The compression ratio can also be calculated based on the swept volume after the closure of the intake port. This is often called the "dynamic compression ratio".

Example

For an engine with a bore of 54.0 mm and a stroke of 54.5 mm. It has a cylinder head volume of 8.5 CC and the exhaust port opens 28 mm after tdc. Enter this data into the compression ratio programme as shown. The resultant trapped compression ratio is calculated as 8.54.

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