Calculate engine displacement, compression ratio, and piston speed for performance builds, restorations, and racing applications. Essential tools for engine builders and enthusiasts.
Calculate total engine displacement from bore, stroke, and cylinder count. Results shown in both cubic inches (CI) and liters.
Formula: Displacement = (π/4) × Bore² × Stroke × Cylinders
Calculate compression ratio from swept volume and clearance volume. Critical for selecting camshafts, fuel octane requirements, and preventing detonation.
Formula: CR = (Swept Volume + Clearance Volume) / Clearance Volume
Calculate average piston speed to evaluate engine stress and longevity. High piston speeds increase wear and require stronger components.
Formula: Piston Speed (ft/min) = (Stroke × RPM × 2) / 12
Piston Speed Guidelines: Under 4,000 ft/min = Street engine | 4,000-4,500 ft/min = Performance street | Over 4,500 ft/min = Racing engine
These calculators are essential tools for anyone planning an engine build, rebuild, or modification. Understanding displacement, compression ratio, and piston speed helps you select compatible components and predict engine behavior.
Engine displacement represents the total volume swept by all pistons during one complete rotation of the crankshaft. Larger displacement generally means more power potential, but also affects vehicle classification, insurance rates, and racing class eligibility. Common modifications to increase displacement include boring cylinders to a larger diameter (overbore) or installing a crankshaft with longer stroke (stroker kit).
Low Compression (8.0:1 - 9.5:1): Compatible with boost (turbo/supercharger), runs on regular fuel, good for street reliability.
Medium Compression (9.5:1 - 11.0:1): Best for naturally aspirated street performance, requires premium fuel, excellent balance of power and drivability.
High Compression (11.0:1 - 13.0:1): Maximum naturally aspirated power, requires race fuel or E85, careful tuning essential to prevent detonation.
Race Compression (13.0:1+): Purpose-built racing engines, requires race fuel, aggressive camshaft profiles, not suitable for street use.
Piston speed directly affects engine durability and component stress. The piston must accelerate, stop, and reverse direction twice per revolution. Higher piston speeds increase loads on connecting rods, bearings, rings, and cylinder walls. Long-stroke engines reach high piston speeds at lower RPM than short-stroke engines, which is why high-revving engines typically have oversquare (bore > stroke) designs.
Small Block Chevy 350: 4.00" bore × 3.48" stroke = 349 CI (5.7L)
Small Block Chevy 383 Stroker: 4.03" bore × 3.75" stroke = 383 CI (6.3L)
Big Block Chevy 454: 4.25" bore × 4.00" stroke = 454 CI (7.4L)
LS3 Corvette: 4.06" bore × 3.62" stroke = 376 CI (6.2L)
Ford Windsor 302: 4.00" bore × 3.00" stroke = 302 CI (5.0L)
Ford Windsor 347 Stroker: 4.00" bore × 3.40" stroke = 347 CI (5.7L)
| Engine | Bore | Stroke | Displacement |
|---|---|---|---|
| Chevy 305 | 3.736" | 3.48" | 305 CI (5.0L) |
| Chevy 350 | 4.00" | 3.48" | 350 CI (5.7L) |
| Chevy 383 | 4.03" | 3.75" | 383 CI (6.3L) |
| Chevy 454 | 4.25" | 4.00" | 454 CI (7.4L) |
| LS1/LS6 | 3.898" | 3.622" | 346 CI (5.7L) |
| LS3 | 4.065" | 3.622" | 376 CI (6.2L) |
| Ford 302 | 4.00" | 3.00" | 302 CI (5.0L) |
| Ford 351W | 4.00" | 3.50" | 351 CI (5.8L) |
| Mopar 340 | 4.04" | 3.31" | 340 CI (5.6L) |
| Mopar 360 | 4.00" | 3.58" | 360 CI (5.9L) |