Engine Capacity

Engine Capacity = Swept Volume = Engine Displacement

We use all of these terms interchangeably and they all mean the same thing

When we calculate the capacity of an engine it is simply the bore, stroke and number of cylinders calculation. The swept volume of a single cylinder is the cylindrical volume = stroke x pi x bore2 / 4

An engine with a bore = 25mm and a stroke = 50mm has a capacity of 24500mm3 and you need to divide this by 1000 to convert to cubic centimeters = 24.5cc

Our excel workshop calculation has a tab for engine calculations and has this all in a simple spreadsheet.

We can achieve the same engine displacement by changing the bore and stroke, this will result in the same engine capacity, but those engines will have different characteristics.

If the stroke is bigger than the bore we term this a long stroke engine, characteristically: slow revving, tall and with higher torque.

The simple calculator below will let you enter bore and stroke and calculate engine capacity in cubic centimeters (cc) and cubic inches (cu. in).

Examples

EngineBore, mmStroke, mmCapacity, ccNotes
Cox Babe Bee 04910.319.80.82Small free-flight commercial glow plug engine first sold in 1956 for $3.95
Briggs & Stratton 300E6044.5125Single cylinder lawnmower engine
Ford Model T95.25101.62895First production vehicle.
Cosworth DFV V885.6764.92993Famous naturally aspirated F1 engine from the 1960s to 1980s
Rolls Royce V12 Merlin137.3152.527094Supercharged V12 that powered the Spitfire, Hurricane, Lancaster and North American Mustang

Leave a comment