Chamber Volume for a Target Compression Ratio
The combustion-chamber volume needed to hit a target static compression ratio.
Example
You enter
- Bore (in) 4
- Stroke (in) 3.48
- Target compression ratio (x:1) 10.73
- Head-gasket bore (in) 4.1
- Head-gasket thickness (in) 0.04
- Deck clearance (in) 0.005
You get
- Required chamber volume 64.0 cc
Details, formula, and sources
TDC_volume = cylinder_cc / (target_CR - 1) and chamber = TDC_volume - gasket - deck + dome. A 4.0 x 3.48 in cylinder (716.7 cc) targeting 10.73:1 needs a 64 cc chamber; drop the target and the chamber grows. Tells you how much to mill the head or how large a dished/domed piston to run for a target CR, instead of the CR from one chamber. Static CR only; cc'ing the actual chambers governs.
TDC_volume = cylinder_cc / (target_CR − 1); chamber_cc = TDC_volume − gasket − deck + dome. The inverse of CR = (cylinder_cc + TDC_volume) / TDC_volume. 1 in³ = 16.387 cc.
Classical engine-design geometry; SAE J604 displacement by name.
SAE standards licensed; principles free in published engine-design texts.
Estimate. AHJ and licensed professional govern.
Field names used by the API: bore_in, stroke_in, target_cr, gasket_bore_in, gasket_thickness_in, deck_clearance_in, chamber_cc
- Static CR only solves the static geometric CR; dynamic CR, cam timing, and quench are not modeledengine-design geometry
- Bore / stroke / clearance inputs user-suppliedOEM service manual or measurement