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    Producing Quality Computer Tools for Racers and Engine Builders since 1986






Cylinder Volume

What is Cylinder Volume?

Cylinder Volume is the volume of each cylinder in the engine, and is made up of 2 parts.

1) First is the swept volume, which is pretty easy to figure out. The formula for the Swept Volume of the cylinder is Pi X radius squared X the height. For engine's, this would be:

     Swept Volume = 3.14159 x (Bore/2) x (Bore/2) x Stroke

Swept Volume x number of cylinders in the engine is the engine's displacement. This is the number most people think of when describing the engine's size. You can change an engine's displacement by changing it's bore, stroke or number of cylinders.

2) Second is the combustion chamber volume at the top of the piston, when the piston is at top dead center (TDC). This is made up of the volume in the Cylinder Heads combustion chamber, any depression (dish) in the piston, and other minor volumes.

The ratio of the cylinder's swept volume to the combustion chamber volume is the Compression Ratio of the engine.

    Compression Ratio  =    Swept Volume + Combustion Chamber Volume 
                                                  Combustion Chamber Volume

Swept volume affects how much air the engine can pump and therefore engine performance level. Compression ratio has a significant impact on engine performance, and the likelihood for detonation. For certain classes of racing, the swept volume and/or compression ratio are limited by the rules. Therefore, engine builders must pay especially close attention to cylinder volumes.

Programs that take Cylinder Volume into account

We have 3 programs that work with Cylinder Volume when conducting Engine SimulationEngine Analyzer v3.4, Engine Analyzer Plus v3.4. And Engine Analyzer Pro v3.9 also uses Cylinder Volume in Engine Simulation.

And we have 2 other programs that take Cylinder Volume into account when making calculations. Compression Ratio Calculator v2.3, and Engine Log Book v1.1.