Engine / Volume
Engine Displacement Calculator: Bore, Stroke and Cylinders
Calculate swept engine volume in cc, litres and cubic inches, or enter a target displacement to solve for bore or stroke.
Engine Displacement Calculator: Bore, Stroke and Cylinders: Adds the swept volume of equal circular cylinders using bore, stroke and cylinder count. Reverse modes solve bore or stroke for a target displacement. The volume excludes combustion-chamber clearance. Runs 100% locally in your browser with zero server file uploads.
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Bore 86.000 mm × stroke 86.000 mm × 4 cylinders
V (cc) = π × bore² × stroke × cylinders ÷ 4000, with lengths in mm. Bore = √[4000V ÷ (π × stroke × cylinders)]. Stroke = 4000V ÷ (π × bore² × cylinders). 1 in³ = 16.387064 cc.
For circular cylinders with equal bore and stroke. Swept volume excludes combustion-chamber clearance. NASA: bore and stroke
Swept volume
NASA Glenn, Bore and Stroke: piston area is πB²/4, and swept volume is area multiplied by stroke. Multiply by cylinder count and convert mm³ to cc by dividing by 1000. https://www.grc.nasa.gov/www/k-12/airplane/stroke.html
Reverse and unit conversions
For displacement V in cc, bore B and stroke S in mm, and cylinder count N: B = √(4000V/(πSN)); S = 4000V/(πB²N). One litre is 1000 cc, and one cubic inch is exactly 16.387064 cc.
How to use it
- Choose displacement, bore or stroke as the unknown.
- Enter the known dimensions in millimetres, cylinder count and target volume where needed.
- Read the solved dimensions and displacement in three units.
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Engine dimensions are processed in your browser.
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Frequently asked questions
Does displacement include the combustion chamber?
No. It measures the volume swept by the piston from top to bottom dead centre, summed across the cylinders.
Why is an 86 mm by 86 mm four-cylinder engine about two litres?
Its swept volume is π/4 × 86² × 86 × 4 / 1000, approximately 1998.23 cc or 1.998 L.
Does a reverse result prove the engine can be built?
No. It solves geometry only. Wall thickness, piston and rod design, clearances and structural limits require separate checks.
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