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Engine Displacement Calculator

Calculate engine displacement from bore, stroke, and cylinder count. Solve for bore or stroke with unit conversions.

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What is the Engine Displacement Calculator?

The Engine Displacement Calculator is a free online tool for computing total engine displacement from bore, stroke, and cylinder count. It uses the formula CID = N × (π/4) × B² × S. You can also solve for bore or stroke when displacement and the other dimensions are known.

This calculator is essential for automotive enthusiasts, engine builders, mechanics, and students working on engine design, performance tuning, and restoration projects.

How to Use the Engine Displacement Calculator

Select what you want to solve for from the dropdown menu. Enter the number of cylinders, bore diameter, and stroke length. Choose your preferred units (inches, millimeters, or centimeters). The calculator instantly computes the displacement in cubic inches and liters with a detailed step-by-step breakdown.

Understanding the Engine Displacement Formula

CID = N × (π/4) × B² × S

CID is total displacement in cubic inches, N is number of cylinders, B is bore diameter, and S is stroke length. Convert to liters by dividing by 61.024.

Applications

  • Engine building and rebuilding: verifying bore and stroke choices
  • Performance tuning: computing displacement for intake and carburetor sizing
  • Racing classification: checking displacement-based class limits
  • Engine swap planning: comparing donor engine displacement
  • Automotive education: learning engine geometry fundamentals

Frequently Asked Questions

How do you calculate engine displacement?

Use CID = N × (π/4) × B² × S where N is cylinders, B is bore diameter in inches, and S is stroke in inches. Multiply bore² by 0.7854 (π/4) for bore area, then multiply by stroke and cylinder count.

How do I convert cubic inches to liters?

Divide cubic inches by 61.024. For example: 350 in³ / 61.024 ≈ 5.74 L; 454 in³ / 61.024 ≈ 7.44 L; 302 in³ / 61.024 ≈ 4.95 L (often rounded to 5.0 L).

What is the difference between bore and stroke?

Bore is the inner diameter of the cylinder (how wide it is). Stroke is the distance the piston travels from bottom dead center to top dead center. Bore-to-stroke ratio influences engine character: oversquare favors high-RPM horsepower; undersquare favors low-end torque.

Does displacement include the combustion chamber?

No. Displacement is the swept volume only. The volume above top dead center is the clearance volume used to compute compression ratio, not displacement.

Why is a 5.0 L V8 sometimes called a 302?

Ford's 5.0 L V8 displaces 302 in³ (302 / 61.024 ≈ 4.95 L, rounded up to 5.0). Marketing uses metric while engineers use SAE cubic inches. Chevy's 350 ci is 5.7 L, and the Hemi 426 is 7.0 L.

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