Typically 0.030"–0.060" (0.75–1.5 mm) larger than cylinder bore to prevent chamber overhang.
Combustion Chamber & Piston
Results
Static Compression Ratio
—
: 1
Total Displacement
—
in³
Piston-to-Head (Quench)
—
in
Piston Deck Clearance
—
in
Total Combustion Volume
—
cc
Rod-to-Stroke Ratio
—
ratio
⛽
Fuel System Sizing Calculator
Determines the minimum fuel pump flow and injector size needed for your target power level.
Results are based on actual fuel demand — size your pump above this to ensure margin at rated pressure.
4 Cyl6 Cyl8 Cyl
80% (Recommended)
3.0 bar / 43.5 psi4.0 bar / 58.0 psi
43.5 psi (3 bar)58.0 psi (4 bar)
7 psi (0.5 bar)14.5 psi (1 bar)22 psi (1.5 bar)
Results
Recommended Fuel Pump Capacity (+25% Headroom)
—
lph
Injector Size Required (per cylinder)
—
lb/hr
Minimum Fuel Demand (Engine 100%)
—
lph
Peak Full-Boost Fuel Rail Pressure
—
psi
Effective Injector Delta Pressure (ΔP)
—
psi
Flow Correction Factor
—
× rated injector flow
Pump Selection Guidance: Ensure your chosen fuel pump delivers at least — at your peak rail pressure of —. Electric fuel pump flow drops substantially as operating pressure increases.
⚙️
Gear Ratio & Vehicle Speed Calculator
Calculates vehicle speed in each gear at a given RPM. Enter "0" or leave a gear blank to skip it.
Use the tire helper to convert a P/E-metric tire size to overall diameter.
Enter a metric tire size (e.g. 245/45R17) to calculate outside diameter.
Gear Ratios
Speed at — RPM
GearRatioSpeedOverallShift Recovery
Cruising RPM at 70 mph (113 km/h)
—
RPM in top gear
Cruising RPM at 80 mph (129 km/h)
—
RPM in top gear
🔥
Exhaust Header Sizing Calculator
Calculates primary tube inside diameter and tuned primary lengths based on your engine's
displacement, cam timing, and target RPM. Lengths are measured as the tube centerline path.
Mild Street (212°)Street/Strip (224°)Hot Street (236°)Race / Track (252°)
NA Gas (1350°F / 732°C)Boosted (1550°F / 843°C)
Compact Head (2.5")Standard V8 (3.0")Deep Port (3.5")
The acoustic runner begins at the exhaust valve face. Deducting internal port length ensures the fabricated header tube matches the tuned harmonic.
Results
Recommended Primary Tube Size (O.D.)
—
16-gauge (0.065" wall) standard mandrel tubing
Primary Inside Diameter (I.D.)
—
inches (— mm) calculated bore
Collector Size & Merge Choke
—
—
Tuned Collector Length
—
inches (— mm) secondary resonator
Stepped Header Recommendation
—
broadens mid-range torque curve
Acoustic Speed of Sound
—
ft/s in exhaust gas
Fabricated Primary Tube Length Options
Physical tube lengths measured from the header flange to the collector entry along the centerline
(with cylinder head port length deducted). Choose based on available engine bay packaging and desired power curve width:
Fabrication Tip: For equal-length headers, aim to keep all primary tubes within ±0.75" (19 mm) of each other. Round diameter up to the nearest available commercial tubing size for high-RPM / boost applications.