Pick a calculation below. Gear-ratio speeds update live across all ten gears as you type.
Setup km/h = (RPM ÷ (gear × final)) × π × dia(in) × 0.0254 × 60 ÷ 1000
Reminder: overall/loaded diameter goes in as inches. Need to convert from a tire size like 255/35R19? Use the "Tire size → wheel diameter" tab.
Speed by gear
Tire size dia = rim + 2 × (width × aspect/100)
e.g. for 255/35R19, enter width 255, aspect 35, rim 19.
Overall diameter
Sidewall height
Torque converter 1 lb·ft = 1.35582 N·m
Type into either field — the other updates instantly.
Power converter 1 kW = 1.34102 bhp
bhp here is mechanical (imperial) horsepower. Type into either field.
Displacement converter 1 cu·in = 16.3871 cc
Type into either field — the other updates instantly.
Inputs CR = (Vsw + Vc) ÷ Vc
Head gasket use compressed thickness, not listed thickness
Gasket bore is usually 0.5–2 mm larger than engine bore. Leave both blank to exclude the gasket (treated as zero volume).
Result
Static CR only — dynamic CR (accounting for cam timing / IVC) requires measured data. All volumes are per cylinder.