Engine Displacement Calculator
Calculate engine displacement from bore, stroke, and cylinders
How to Use
- Enter the bore diameter (cylinder diameter)
- Enter the stroke length (piston travel distance)
- Enter the number of cylinders
- Select your preferred units
- Click calculate to see total engine displacement
What is Engine Displacement?
Engine displacement refers to the total volume of all cylinders in an internal combustion engine. It's a key specification that indicates the engine's size and capacity. Larger displacement typically correlates with more power and torque output.
Displacement is commonly expressed in cubic centimeters (cc), liters (L), or cubic inches (ci). For example, a '350 engine' refers to an engine with approximately 350 cubic inches of displacement.
Displacement Formula
Engine displacement is calculated using:
Displacement = π/4 × bore² × stroke × cylinders
Where:
- bore = cylinder diameter
- stroke = piston travel distance from top to bottom
- cylinders = number of cylinders
- π/4 ≈ 0.7854
Understanding Bore and Stroke
Bore refers to the cylinder diameter - the width of the hole where the piston moves. Stroke refers to the distance the piston travels from its highest point (top dead center) to its lowest point (bottom dead center).
- Long-stroke engine: Stroke > bore (better low-end torque)
- Square engine: Bore ≈ stroke (balanced characteristics)
- Oversquare engine: Bore > stroke (better high RPM power)
Applications and Significance
- Fuel tank sizing: Larger displacement engines use more fuel
- Insurance classification: Affects insurance premiums
- Emissions testing: Displacement determines emission standards
- Racing categories: Many competitions organize by displacement
- Performance tuning: Displacement affects power output potential
- Engine rebuilding: Helps determine component compatibility
Frequently Asked Questions
- Why does displacement matter for engine performance?
- Larger displacement allows more air-fuel mixture per combustion cycle, which typically produces more power and torque. However, efficiency, fuel quality, and engine design also significantly affect overall performance.
- What's the difference between displacement and engine size?
- Displacement is the total volume swept by all pistons. 'Engine size' can refer to displacement, but also to physical dimensions. A 2.0L engine has approximately 2000 cc of displacement.
- How does bore and stroke ratio affect performance?
- Oversquare engines (large bore, short stroke) excel at high RPMs. Long-stroke engines (small bore, long stroke) produce better low-end torque. Square engines offer balanced performance across the RPM range.
- Can you change an engine's displacement?
- Yes, through boring (increasing bore diameter) or stroking (using a longer crank). This is called displacement modification or 'boring and stroking.' It requires precision work and new components like pistons and connecting rods.
- Why is 5.0, 5.7, 7.3, etc. used for engine names?
- These numbers refer to approximate engine displacement in liters. A 5.0L engine has roughly 5000 cc of displacement. This naming convention helps quickly identify the engine's approximate size and power class.