Compression Ratio Calculator

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Calculates the static and dynamic compression ratios of an internal combustion engine. Static compression ratio is based on the engine's physical dimensions, while dynamic compression ratio considers valve timing.

More tools:Science & Lab Calculators

How To Use

How to use this calculator

Start with your values, or try a preset.

Step 1

Enter Bore Diameter, Stroke Length, Cylinder Head Volume, Piston Dome/Dish Volume, Deck Clearance Volume, Intake Valve Closing Point (After Bottom Dead Center - ABDC), and Connecting Rod Length in the units shown.

Step 2

Read Total Combustion Chamber Volume, Cylinder Volume, Total Combustion Chamber Volume (cubic inches), Static Compression Ratio, and Dynamic Compression Ratio in the results panel. Results update as you change the inputs.

Step 3

Choose a preset to load an example, then adjust the values for your situation.

Worked Examples

Example calculations

See the inputs and their calculated results.

Small Block Chevy

Bore Diameter: 4 inches; Stroke Length: 3.48 inches; Cylinder Head Volume: 64 cc; Piston Dome/Dish Volume: -5 cc; Deck Clearance Volume: 10 cc; Intake Valve Closing Point (After Bottom Dead Center - ABDC): 65 degrees; Connecting Rod Length: 5.7 inches

Total Combustion Chamber Volume: 69 cc; Cylinder Volume: 43.7309328 cubic inches; Total Combustion Chamber Volume (cubic inches): 4.210654787 cubic inches; Static Compression Ratio: 11.38577965; Dynamic Compression Ratio: 18.66002776

Ford 302

Bore Diameter: 4 inches; Stroke Length: 3 inches; Cylinder Head Volume: 60 cc; Piston Dome/Dish Volume: 0 cc; Deck Clearance Volume: 10 cc; Intake Valve Closing Point (After Bottom Dead Center - ABDC): 60 degrees; Connecting Rod Length: 5.09 inches

Total Combustion Chamber Volume: 70 cc; Cylinder Volume: 37.69908 cubic inches; Total Combustion Chamber Volume (cubic inches): 4.27167877 cubic inches; Static Compression Ratio: 9.825354628; Dynamic Compression Ratio: 16.37559105

Honda Civic B18C1

Bore Diameter: 3.189 inches; Stroke Length: 3.433 inches; Cylinder Head Volume: 46 cc; Piston Dome/Dish Volume: -2 cc; Deck Clearance Volume: 0 cc; Intake Valve Closing Point (After Bottom Dead Center - ABDC): 52 degrees; Connecting Rod Length: 5.433 inches

Total Combustion Chamber Volume: 44 cc; Cylinder Volume: 27.42030975 cubic inches; Total Combustion Chamber Volume (cubic inches): 2.685055227 cubic inches; Static Compression Ratio: 11.21219582; Dynamic Compression Ratio: 19.18531284

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