🔧 Engine Displacement Calculator
Calculate engine displacement from bore and stroke
Cylinder bore diameter
Piston stroke length
Common: 4, 6, 8 cylinders
How to Use This Calculator
Enter Bore Diameter
Input the cylinder bore diameter in inches. The bore is the diameter of each cylinder. Common values: 3.5", 4.0", 4.25", 4.5". This is typically found in engine specifications or measured with a bore gauge.
Enter Stroke Length
Enter the piston stroke length in inches. Stroke is the distance the piston travels from top dead center to bottom dead center. Common values: 3.0", 3.48", 4.0", 4.25". Check engine specifications or measure from crankshaft throw.
Enter Number of Cylinders
Input the total number of cylinders in your engine. Common configurations: 4-cylinder (I4), 6-cylinder (I6, V6), 8-cylinder (V8). Default is 8 for V8 engines.
Calculate Displacement
Click "Calculate Displacement" to compute the total engine displacement. Results are displayed in both cubic inches (CID) and liters for your convenience.
Formula
Displacement = (π/4) × Bore² × Stroke × Number of Cylinders
Where:
- Displacement = Total engine displacement (cubic inches or liters)
- Bore = Cylinder bore diameter (inches)
- Stroke = Piston stroke length (inches)
- Number of Cylinders = Total cylinders in engine
- π/4 = Constant (approximately 0.7854) for circular cylinder volume
Example Calculation:
For a V8 engine with 4.00" bore, 3.48" stroke:
Displacement = (π/4) × 4.00² × 3.48 × 8
Displacement = 0.7854 × 16 × 3.48 × 8
Displacement = 349.85 cubic inches (≈ 350 CID or 5.7L)
For a 4-cylinder engine with 3.5" bore, 3.0" stroke:
Displacement = (π/4) × 3.5² × 3.0 × 4 = 115.45 CID (1.89L)
Note: This formula calculates the total swept volume of all cylinders. The π/4 factor comes from the area of a circle (πr²) where r = bore/2, so area = π(bore/2)² = (π/4) × bore². Engine displacement is a key specification used for engine classification, performance comparison, and legal/racing categorization.
About Engine Displacement Calculator
The Engine Displacement Calculator computes the total volume displaced by all pistons in an engine during one complete cycle. Displacement is one of the most fundamental engine specifications, indicating engine size and capacity. It's calculated from the bore (cylinder diameter), stroke (piston travel distance), and number of cylinders. Displacement directly relates to potential power output, torque, and fuel consumption characteristics.
When to Use This Calculator
- Engine Design: Calculate displacement when designing or modifying engines
- Engine Identification: Verify engine displacement from bore and stroke measurements
- Performance Analysis: Understand engine size in relation to power output
- Engine Modifications: Calculate new displacement after boring or stroking modifications
- Educational Purposes: Learn how engine geometry relates to displacement
Why Use Our Calculator?
- ✅ Dual Units: Provides results in both cubic inches (CID) and liters
- ✅ Accurate Formula: Uses the standard displacement calculation
- ✅ Quick Calculation: Instantly compute engine displacement
- ✅ Step-by-Step Display: Shows the complete calculation process
- ✅ Free Tool: No registration required, works on all devices
Understanding Engine Displacement
Engine displacement represents the total volume of air/fuel mixture that can be drawn into all cylinders during one complete engine cycle. Larger displacement generally means more power potential, but also typically higher fuel consumption. Displacement is measured in cubic inches (CID) in the United States or liters (L) internationally. A 350 cubic inch engine equals approximately 5.7 liters.
Common Applications
Automotive Engineering: Engineers use displacement calculations to design engines, determine cylinder sizing, and predict performance characteristics during the design phase.
Engine Modifications: Hot rodders and engine builders calculate new displacement after modifications like boring cylinders (increasing bore) or stroking engines (increasing stroke) to track engine size changes.
Racing Classifications: Many racing organizations categorize vehicles by engine displacement, making accurate displacement calculation essential for compliance and fair competition.
Tips for Best Results
- Measure bore and stroke accurately - small measurement errors multiply in the calculation
- Use actual measured values after modifications rather than nominal specifications
- For overbored engines, use the actual bore diameter after machining
- Remember that displacement doesn't directly equal power - engine efficiency matters greatly
- Displacement is often rounded for marketing (e.g., 350 CID, 5.7L) - actual calculated values may vary slightly
Frequently Asked Questions
What is engine displacement?
Engine displacement is the total volume swept by all pistons in one complete engine cycle. It's calculated by multiplying the area of one cylinder (based on bore) by the stroke length and the number of cylinders. Displacement indicates engine size and is typically measured in cubic inches (CID) or liters (L).
How do I convert cubic inches to liters?
To convert cubic inches to liters, multiply by 0.0163871. For example, 350 cubic inches × 0.0163871 = 5.735 liters (commonly rounded to 5.7L). Conversely, to convert liters to cubic inches, multiply by 61.0237. The calculator automatically provides both measurements.
Does larger displacement always mean more power?
Not necessarily. While larger displacement provides more potential for power, actual power output depends on many factors including volumetric efficiency, compression ratio, fuel type, turbocharging/supercharging, and engine design. A smaller, well-designed engine can often produce more power per liter than a larger, less efficient engine.
What's the difference between bore and stroke?
Bore is the diameter of the cylinder, measured across the cylinder opening. Stroke is the distance the piston travels from top dead center (TDC) to bottom dead center (BDC), determined by the crankshaft throw radius. Bore affects cylinder area, while stroke affects piston travel distance. Both contribute to displacement.
How does boring or stroking affect displacement?
Boring (increasing cylinder bore diameter) increases displacement because you're increasing the cylinder area. Stroking (increasing piston stroke length) also increases displacement because the piston sweeps more volume. Both modifications increase total engine displacement and typically require other engine component changes to work properly.