Example Data Table
This example shows typical engine combinations and their cubic inch displacement.
| Bore (in) | Stroke (in) | Cylinders | Total CID (in³) | Total Displacement (L) |
|---|---|---|---|---|
| 4.00 | 3.48 | 8 | 350.0 | 5.7 |
| 3.50 | 3.94 | 6 | 227.5 | 3.7 |
| 3.30 | 3.50 | 4 | 119.4 | 2.0 |
Formula Used
The displacement of a single cylinder approximated as a right circular cylinder is:
Vcyl = (π / 4) × bore² × stroke
- bore is the cylinder diameter (inches).
- stroke is piston travel from top to bottom (inches).
- π / 4 is the circular area factor.
Total engine displacement in cubic inches is:
CID = Vcyl × number of cylinders
To convert cubic inches to liters this calculator uses:
Displacement (L) = CID × 0.016387064.
How to Use This Calculator
- Enter the bore and select its unit, if using geometry mode.
- Enter the stroke with the correct unit for your measurements.
- Provide the number of cylinders in your engine.
- Optionally, enter total displacement in cc or liters to skip bore and stroke.
- Set your desired decimal precision for rounded results.
- Click “Calculate Displacement” to see per-cylinder and total volumes.
- Use Download CSV or Download PDF to save results.
Compare different combinations quickly when planning rebuilds, swaps, or performance tuning.
Cubic Inch Displacement Deep Dive
Understanding Engine Size in Practical Terms
Engine size expressed in cubic inches tells you how much air and fuel an engine can theoretically draw in one complete four-stroke cycle. Larger displacement usually means greater torque potential, stronger low-end pull, and more flexibility for performance upgrades or towing work.
Relationship Between Bore, Stroke, and Power
Increasing bore allows larger valves and improved breathing at high rpm. Longer stroke improves leverage on the crankshaft and low-speed torque. This calculator lets you explore different bore and stroke pairings to match intended engine behavior with your driving style.
Comparing Cylinders and Engine Configurations
Engines with many smaller cylinders can rev smoothly while maintaining good displacement. Fewer large cylinders may deliver a different torque curve and sound. By changing cylinder count while keeping total cubic inches similar, you can study configuration effects without losing overall capacity.
Translating Between Cubic Inches, Liters, and Cubic Centimeters
Manufacturers often publish engines in liters or cubic centimeters. This tool automatically converts cubic inches to liters and cc using precise factors. That means you can directly compare domestic V8 figures with metric specifications used for modern compact vehicles and motorcycles.
Using Displacement for Tuning and Component Selection
Accurate displacement helps you choose carburetors, injectors, camshafts, and exhaust systems. Many tuning charts reference engine size ranges. Entering your actual bore, stroke, and cylinder count here ensures you select appropriately sized components instead of relying on marketing names or approximate labels.
Planning Future Modifications and Overbores
When rebuilding an engine, machinists may increase bore slightly within safe limits. This calculator lets you model standard, oversize, and stroker combinations before committing. You can see the exact cubic inch changes and judge whether the gain justifies machining cost and parts selection.
Documentation, Record Keeping, and Comparison
The CSV and PDF download features help you archive multiple setups for future comparison. Keeping displacement records alongside compression ratio, cam data, and dyno results provides a valuable logbook. Over time, you can understand which displacement ranges delivered the best reliability and performance.
Frequently Asked Questions
What does cubic inch displacement actually measure?
It measures the total swept volume of all cylinders as pistons move from top dead center to bottom dead center. It does not include combustion chamber volume or intake manifold volume.
Why are results shown in cubic inches and liters together?
Many classic engines are described in cubic inches, while modern specifications usually list liters. Showing both units lets you compare historical and modern engines quickly without doing manual unit conversions.
Does this calculator account for turbochargers or superchargers?
No, the tool only calculates geometric displacement based on cylinder size and count. Forced induction changes airflow and power output, but it does not change the actual physical displacement.
Can I mix units for bore and stroke values?
Yes. You may select inches, millimeters, or centimeters independently for bore and stroke. The calculator converts every value into inches internally before applying the displacement formulas.
How accurate are the displacement results?
The mathematics uses precise constants and conversions, so numerical accuracy is very high. Real engines can differ slightly due to manufacturing tolerances, wear, and machining variations during rebuilding.
May I use this tool for motorcycles and small engines?
Absolutely. As long as you know bore, stroke, and cylinder count, this calculator works for motorcycles, marine engines, lawn equipment, generators, and other multi-cylinder or single-cylinder machines.