How to Determine an Engine's Cubic Inches

Determining the cubic inch displacement of an engine requires some basic math and a knowledge of the bore and stroke of the engine. This information is not always easy to find, however, and may require you to partially disassemble the engine.

Difficulty: Moderately EasyInstructionsThings You'll Need:

Calculator
Cylinder micrometer
Calipers

Step 1
Look through the driver's side windshield at the lower corner of the dashboard. There should be a vehicle identification number stamped in a metal plate. Copy this number down and call your local dealer. Ask the parts department to tell you what engine you have in your car. They can also tell you the engine displacement.
Step 2
Convert the number the dealer gave you from cubic centimeters to cubic inches with this formula: cubic centimeters X 0.06102374409 = cubic inches
Step 3
Remove the cylinder head from the engine if you have been unable to find the bore and stroke information. This is a complicated procedure on anything but a small engine, and is not recommended for a novice.
Step 4
Measure the diameter of the cylinder with the cylinder micrometer. This is the bore.
Step 5
Turn the engine flywheel until one of the pistons is at the bottom of the stroke. Measure from the top of the piston edge to the top of the cylinder. This is the stroke.
Step 6
Divide the bore by two to obtain the radius. Multiply the radius by itself and then multiply that result by 3.14. This is the area of the top of the piston.
Step 7
Multiply the area of the piston by the length of the stroke. This is the cubic inches of that one cylinder.
Step 8
Multiply the cubic inches of the one cylinder by the number of cylinders in the engine. The resulting number is the cubic inch displacement of the engine.