Production - Useful Information

How to Calculate Engine Capacity

By Trevor Hedge

The measurements you need to work this out are the bore and stroke dimensions. Take half of the bores' dimension and multiply it by itself, then multiply by Pi (3.14). Next, take the stroke dimension and multiply this by the previous figure you calculated, then multiply this number by the number of cylinders in the engine and there you have it.

For an example we will use my stroked V8. This was a 318 fitted with a 360 crank and bored 30 thou. So we take the 3.91 bore of the 318 and add the 30 thou overbore which gives us 3.94 and divide it by 2, which gives us 1.97. We then multiply this figure of 1.97 by itself, and then by Pi which is 3.14 which then gives us 12.186026. We now take this figure and multiply this by the 360 cranks' stroke which is 3.58, 12.186026 multiplied by 3.58 gives 43.62597308. Now we then multiply this by the number of cylinders which is 8, so 43.62597308 multiplied by 8 is 349.00778464.  At last this gives us the final engine capacity of around 349 cubic inches.

Now if you want to know how many cubic centimetres your engine displaces you multiply the cubic inches by 16.43. So our 349 multiplied by 16.43 gives us 5734, which is how many cc's my engine displaced.

You can use the method described for determining capacity with the bore and stroke dimensions in centimetres or millimetres to give you cc in the first place if you are more metric minded. But remember if you use millimetres you will have to move the decimal place three places to the left when you get your final figure for it to be in cubic centimetres.

Now that you have learnt how to perform this calculation, if it all seems like too much effort you can simply use our online calculation function.