mmCylinder diameter.
mmDistance the piston travels from bottom to top dead centre.
Result
Total displacement689.6 cc
How it is calculated, with your numbers
- Displacement per cylinder
per = π / 4 × bore² × stroke / 1000π / 4 × 80² × 68.6 / 1000 = 344.8 cc - Total displacement
cc = per × cyl344.821 × 2 = 689.6 cc
Working uses the metric units the formula is written in.
- bore Bore (mm)
- stroke Stroke (mm)
- cyl Cylinders
- per Displacement per cylinder
- cc Total displacement
What it means
Each cylinder sweeps a cylinder of air: the area of the bore (π/4 × bore²) times the stroke. Multiply by the number of cylinders for the engine's swept volume. Dividing cubic millimetres by 1,000 gives cubic centimetres (cc).
Makers usually round the result, so a 689.6 cc engine is sold as a "690" or "700". When you rebore an engine, put the new bore in to see the new size.
Assumptions and limits
- Swept volume only. The combustion chamber volume is not included (see the compression ratio calculator).
Sources
- Heywood, J. B., Internal Combustion Engine Fundamentals, McGraw-Hill, 1988.
Related calculators
Compression ratio calculatorStatic compression ratio from bore, stroke, chamber, gasket, deck height and piston volume.Bore-stroke and rod ratio calculatorBore/stroke ratio and rod/stroke ratio, the two numbers that shape an engine's character.Mean piston speed calculatorAverage piston speed from stroke and rpm, the classic measure of how hard an engine is revving.