Gearhead Drag

From a hobby gearhead to a professional engine or chassis builder, Gearhead Drag saves you time! Gearhead Drag is the calculator app that us gearheads use for many performance automotive parameters. It calculates or estimates numerous engine, exhaust, gearing, tire, suspension, acceleration, weather effects, and other vehicle parameters along with tap and drill sizes. Gearhead Drag works in both standard and metric units and even has advanced settings to customize the calculations to your specific scenario so you can select the most compatible parts for your application.

Gearhead Drag calculates or estimates:

Speed/Gearing
- Engine RPM from vehicle speed, gearing, tire size
- Vehicle Speed from engine RPM, gearing, tire size
- Axle Gear needed for a specific RPM at a certain speed with a given tire size
- Tire Diameter and Cross section width from sidewall size
- Simple gear ratios based on drive and driven tooth count

Engine
- Displacement from cylinders, bore, and stroke
- Bore/Stroke ratio
- Static Compression Ratio
- Average Piston Speed
- Airflow
- Connecting Rod Ratio
- Maximum connecting rod angle from cylinder axis
- Compression Height (piston wrist pin height)
- Dynamic Compression Ratio from the point the intake valve closes
- Head gasket volume (from bore and compressed thickness if round)
- Valve opening and closing events from the cam duration, IC, and LSA
- Cam specs from the valve opening and closing events
- Valve overlap
- Valve lift based on new rocker ratio or lobe lift and rocker ratio
- Valve spring forces from valve spring specs to actual installed height and lift
- Mark dimension on your balancer to set a desired timing advance

Engine Externals
- Minimum air filter size for your engine
- Recommended header primary tube size for your engine
- Recommended exhaust size for your engine
- Cross-sectional flow area of a pipe, or the pipe size from a desired flow area

Suspension
- Instant Center and Anti-Squat of a 4 link rear suspension
- Cg height of your vehicle using the raise one end method

Weather
- Specific humidity
- Air Density Index
- MSA density altitude
- Power Correction Factor of the current weather conditions

Power
- Power from Torque and RPM, or vice versa

Fasteners and Threading
- Lookup a cutting tap drill size

Fuel System
- Total Fuel system flow for fuel pump selection
- Fuel injector flow for injector selection
- Convert an injector flow rating to a new pressure or flow

Acceleration
- Power of your engine based on your drag racing performance and weight
- Drag performance based on power and weight
- Time you would run on a ¼ mile track (.4 km) based on 1/8 mile (.2 km) performance
- ET or speed based on a previous ET or speed and a weight or weather change
- More power needed to achieve a new ET or speed

If you are looking for more please check out our "Gearhead Pro" app.
None of our apps have ads or use special permissions.