ICE-05 — Displacement

ASSUMPTION — Formulas assume ideal cylinder geometry; real combustion-chamber shape and clearances affect total volume. This lesson covers swept volume.

In this lesson you will learn:

• How to compute single-cylinder volume
• How to find total displacement
• How displacement relates to engine character

1. Swept Volume

The volume swept as the piston moves from TDC to BDC is the swept volume: the cylinder cross-section (πD²/4) times stroke (S).

FACT — Single-cylinder swept volume: Vd = (π/4) × D² × S. Total displacement = Vd × cylinder count.

2. Example

EXAMPLE — Bore 80 mm (0.08 m), stroke 90 mm (0.09 m), 4 cylinders: single-cylinder volume ≈ (π/4) × 0.08² × 0.09 ≈ 0.452 L; total ≈ 1.81 L. This is a calculation example only, not a specific OEM engine.

3. Units

FACT — 1 litre = 1000 cc. A “1.6 engine” means roughly 1600 cc of total swept volume.

4. What Displacement Affects

Larger displacement draws more air-fuel per cycle, hence more potential torque.

FACT — Displacement alone does not determine power; volumetric efficiency (ICE-08), boost (ICE-15) and RPM also matter. A small turbo engine can out-power a larger naturally-aspirated one (downsizing).

5. Summary

• Swept volume = (π/4) × bore² × stroke.
• Total displacement = single-cylinder volume × cylinder count.
• Units: cc or litre.
• Displacement is only one component of power capacity.

6. Sources

• Heywood, Internal Combustion Engine Fundamentals
• Bosch Automotive Handbook

Next Lesson

• ICE-06 — Compression Ratio: volume ratio and its effect on engine character.