Automotive Calculators

Working with automotive quantities

Engine maths is geometry, and the relationships are not intuitive. Displacement scales with the square of the bore but only linearly with the stroke, which is why stroking an engine adds capacity faster than boring it — and why bore changes of thirty thousandths matter more than they sound.

Worth knowing: Manufacturer displacement figures round generously. A "350" is 350 cubic inches on paper and closer to 355 once bored thirty over.

These 6 calculators cover about 22,690 searches a month between them. Every one prints the formula it uses and a worked example, so you can check the result by hand before you order.