7 categories · 25 calculators
Engine Building Calculators
Compression, cam timing, airflow, gearing and the rest of the arithmetic an engine build runs on. Everything works out of the box with sensible defaults, shows the formula it used, and runs entirely in your browser — no login, and nothing you type leaves the page.
Displacement & Geometry
- Engine Displacement CalculatorWork out engine displacement in cubic inches, cc and liters from bore, stroke and cylinder count. Imperial or metric.
- Bore / Stroke Ratio CalculatorDivide bore by stroke to see whether an engine is oversquare, square or undersquare, and what that means for the power band.
- Rod Ratio CalculatorCalculate connecting rod ratio from rod length and stroke, with guidance on side loading, piston dwell and where each range belongs.
- Deck Height & Deck Clearance SolverSolve block deck height, deck clearance, compression height, rod length or stroke — leave any one field blank and get the fifth value.
- Overbore & Stroker Displacement ChangeCompare displacement before and after an overbore or stroker crank, in cubic inches, cc and percentage gained.
Compression
- Static Compression Ratio CalculatorCalculate static compression ratio from bore, stroke, chamber cc, piston dish or dome, head gasket and deck clearance.
- Dynamic Compression Ratio CalculatorDynamic compression ratio from your static compression plus the camshaft intake valve closing point. The number that actually predicts detonation.
- Cranking Compression Pressure EstimateEstimate cranking compression pressure in psi from dynamic compression ratio, with altitude and polytropic exponent adjustment.
- Boosted / Effective Compression RatioEffective compression ratio under boost. Enter static compression and boost pressure to see what the engine really sees.
Camshaft & Valvetrain
- Cam Centerline & Lobe Separation AngleWork out intake and exhaust centerlines, duration, lobe separation angle, installed advance and overlap from the four seat-to-seat cam card figures.
- Valve Overlap CalculatorCalculate valve overlap in degrees from intake duration, exhaust duration and lobe separation angle, with idle quality guidance.
- Valve Spring Pressure & Coil Bind CheckOpen spring pressure from seat pressure, rate and lift, plus a coil bind clearance check against installed height.
- Rocker Arm Ratio & Net Valve LiftGross and net valve lift from lobe lift, rocker arm ratio and valve lash, plus a side-by-side comparison of two rocker ratios.
Airflow & Fuel
- Carburetor CFM CalculatorSize a carburetor from displacement, peak RPM and volumetric efficiency using the standard CID × RPM × VE ÷ 3456 formula.
- Fuel Injector Sizing CalculatorSize fuel injectors from target horsepower, BSFC, injector count and duty cycle. Results in lb/hr and cc/min, plus the horsepower a given injector supports.
- Volumetric Efficiency CalculatorCalculate volumetric efficiency from measured airflow, or estimate it from horsepower, BSFC and air/fuel ratio.
- Air/Fuel Ratio & Lambda CalculatorConvert between air/fuel ratio and lambda for petrol, E85, ethanol, methanol, diesel and LPG, with a cross-fuel equivalence table.
Rotating Assembly
- Mean Piston Speed CalculatorMean piston speed in feet per minute and meters per second from stroke and RPM, with guidance on where each range belongs.
- Torque and Horsepower CalculatorConvert between torque, horsepower and RPM. Leave any one of the three blank and it is solved from the other two.
- Bobweight CalculatorCalculate bobweight for balancing a rotating assembly from piston, pin, ring, lock and connecting rod end weights.
Exhaust
Reference
- Gear Ratio, RPM and Road Speed CalculatorConvert between engine RPM and road speed using tire diameter, axle ratio and transmission gear, with a P-metric tire size converter.
- Tire Size to Diameter ConverterConvert a P-metric tire size such as 275/60R15 into overall diameter in inches for gearing calculations.
- Engine Builder Unit ConverterConvert the units engine work runs on: inches and millimeters, cc, cubic inches and liters, psi and bar, horsepower and kilowatts, lb-ft and N·m.
Ad · responsive