Engine calculations

Engine displacement

The volume swept by piston in IC engine in a single movement from TDC to BDC.

  

Displacement= (π/4) * stroke * bore * bore * number of cylinders

Stroke length 

In reciprocating engine the piston moves in one direction first and then exactly opposite direction(TDC to BDC and BDC to TDC).Each of the movement is called stroke or stroke length.

Stroke lenght= engine displacement /(0.7854 * bore *bore *number of cylinders)

Compression Ratio

In an internal combustion engine, the ratio of the volume between the piston and cylinder head before and after a compression stroke is called compression ratio.A compression ratio of six means that the action of the piston compresses the mixture to one-sixth its original volume.

Compression ratio = (swept volume + total chamber volume) / total chamber volume    Cylinder bore diameter Cylinder bore diameter = square root of [engine displacement/(stroke X 0.7854 X number of cylinders)]  Swept volume   The volume of cylinder swept by the piston while move to TDC to BDC or BDC to TDC is called swept volume. Swept volume (cc) = cylinder bore diameter (inches) X cylinder bore diameter (inches) X stroke (inches) X 12.8704