Five free planning tools for drag racers: ET, horsepower, rear gears, turbo airflow and nitrous system research.
Results update as you change inputs. All figures are estimates for planning, not guaranteed track results.
Convert between eighth-mile and quarter-mile ET using a selectable multiplier. Use your actual timeslip when available.
Typical 1/8-to-1/4 ET multipliers are about 1.55–1.60, but vary with power delivery, gearing, traction and vehicle setup. This is an estimate, not a timeslip.
Estimate quarter-mile power using a common empirical formula. For eighth-mile times, the tool first applies your conversion factor.
HP ≈ race weight ÷ (quarter-mile ET ÷ 5.825)³. This empirical formula is a rough estimate and is not a wheel-horsepower dyno result. Traction, aero, drivetrain loss and ET conversion affect accuracy.
Compare trap RPM with tire height, transmission ratio and estimated converter slip. Use the gear comparison below to plan a change.
Estimated engine RPM = MPH × rear gear × transmission ratio × 336 ÷ tire diameter ÷ (1 − converter slip). Actual rolling diameter, tire growth and slip can differ.
Estimate airflow needed for a target horsepower and compare rough compressor flow capacity. This is an early research tool—not a compressor-map match.
Airflow target ≈ HP × selected lb/min per HP. Engine displacement and boost do not uniquely determine compressor suitability. Verify pressure ratio, corrected airflow, efficiency islands, turbine/backpressure, fuel and thermal limits using the manufacturer compressor map and an experienced tuner.
Estimate the additional fuel flow a nitrous horsepower increase may require, then review system-specific safety checks. This does not determine jet sizes.
Fuel flow is an illustrative engineering estimate: added HP × selected BSFC ÷ fuel density. The margin is planning headroom, not a guaranteed safety factor. Actual nitrous enrichment and fuel jetting depend on the specific kit, flowing pressure, fuel type, tune and manufacturer instructions.
Do not substitute generic jet numbers for your system manufacturer’s chart. Fuel jet sizes, bottle pressure, fuel pressure, solenoid flow and timing strategy are not interchangeable across kits or fuels. Follow kit instructions and seek professional tuning for high-output combinations.