Engine Displacement and Compression Ratio
Cubic inches / liters and static CR from bore, stroke, chamber, gasket, deck, and dome volumes.
Example
You enter
- Bore (in) 4
- Stroke (in) 3.48
- Cylinders 8
- Combustion chamber (cc) 64
- Gasket bore (in) 4.1
- Gasket thickness (in) 0.04
- Deck clearance (in; negative if the piston sits above the deck) 0.005
You get
- Displacement (in³) 349.85
- Displacement l 5.73
- Compression ratio 10.73:1
- Premium octane required Yes
Checked against published worked examples from: PowerNation.
Details, formula, and sources
Formula or tableDisplacement (in³) = π × (bore/2)² × stroke × n_cyl. Static compression ratio CR = (V_swept_per_cyl + V_TDC) / V_TDC where V_TDC = chamber + gasket + deck − dome.
Source and editionClassical engine-design geometry; SAE J604 displacement / SAE J1349 power-rating by name.
Free accessSAE standards licensed; principles free in published engine-design texts.
What governsEstimate. AHJ and licensed professional govern.
API field namesbore_in, stroke_in, cylinders, chamber_cc, gasket_bore_in, gasket_thickness_in, deck_clearance_in, displacement_in3, displacement_l, compression_ratio, requires_premium_octane
- Bore / stroke / chamber inputs user-suppliedOEM service manual or measurement