Bore and stroke volume:
With the bore and the stroke volume, the cylinder capacity can be calculated. The formula for a four-cylinder engine is as follows: Vs = π/4 x d² x S x 4
- Bore: This is the cylinder diameter and is always given in mm (in the formula as d).
- Stroke: This is the distance the piston travels in the cylinder (from BDC to TDC) (in the formula as S).
These data are always listed in a car manufacturer’s specifications (e.g. a four-cylinder engine with a bore / stroke of 75 X 90). These values can be used with a formula to calculate the cylinder capacity.
Calculating cylinder capacity:
The cylinder capacity of this four-cylinder engine is calculated using the formula:
- We enter the data of the engine (bore, stroke and the number of cylinders). This yields an answer in cubic millimetres, which is converted to cubic decimetres. This is approximately 1.6 litres.
- Now we take as an example a six-cylinder engine with a bore / stroke volume of 88/85. The cylinder capacity is 3.2 litres.
Long-stroke engine:
When the stroke length is greater than the bore, this is called a long-stroke engine (e.g. 75 X 90).
Square engine:
When the bore is greater than the stroke length, this is called a square engine (e.g. 90 X 75).
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