ET Engine

Data-driven drag racing ET prediction · air density · humidity · elevation · wind · track

Pilot Build v0.9
1Get today's air 2See predicted ET & dial 3Log the pass ↻ repeat every run

Weather Station

Type a location and fetch — temp, humidity, barometer, elevation and wind fill in automatically and stay editable.

Use a trackside weather meter for best results. If pulling from a weather app, keep Sea-level corrected selected and enter track elevation.

Predicted ET — today's air
DA vs baseline
ET vs baseline
Air call
Suggested dial
rounded up · protects the breakout
Physics model
Baseline scaled by air-power correction + wind
Data model (run log)
Needs 3+ logged runs

Run Log

DateETΔ PredMPH60ftDA ftTempRH%BaroGrainsWindTrk°FNotes

Every logged run is checked against what the app predicted right before that run — the Δ Pred column and Model Accuracy tile track how close the calls are getting. Runs logged before this feature show . The data model fits ET vs density altitude across your log — the more runs, the sharper the prediction. Chart: ET vs DA with fitted line.

Computed Air

Density Alt (ft)
Air % of Std

Density altitude is the single best summary number — it rolls temperature, pressure, elevation and humidity into “how high the engine thinks it is.”

Full air analysis (density, dew point, grains, HP correction…)
Air Density (lb/ft³)
Dew Point (°F)
Grains H₂O
Vapor Press (inHg)
Dry Baro (inHg)
HP Correction

Combo Setup

Advanced tuning coefficients

Set the track heading (compass direction the car travels) and fetched wind auto-splits into head/tail component — no guessing at the flags.

Induction sets how sensitive the combo is to air — boosted cars self-correct for thin air, NA cars feel all of it. The advanced coefficients are tunable once you have data; leave track temp at 0 until the log shows a trend.

Baseline Run

No baseline yet — log a pass below and it fills in automatically.

The baseline is your reference pass — every physics prediction scales off it. In Auto mode it follows the last run you log; tap on any logged run to baseline that pass instead.

Parameters In The Model

ParameterEffect on ETHow it's handled
Air temperatureHot air = less oxygen = slowerDensity + HP correction
Humidity / dew pointWater displaces oxygenVapor pressure subtracted from dry baro; grains shown for methanol tuning
Barometric pressureHigher = denser air = fasterStation or sea-level corrected input
ElevationThinner air up highFolded into density altitude
WindHeadwind slows, tailwind helpsDirection-weighted, tunable coefficient
Track temperatureTraction window — nonlinearOptional linear coefficient, logged per run
Induction typeBoosted combos shrug off bad airSensitivity multiplier on air correction
60-ft timesLaunch consistency checkLogged per run for diagnostics

Now live: location-based weather fetch (Open-Meteo model + precise elevation) with auto head/tail wind split via track heading. Future candidates for the full build: on-site weather-station hardware feed, auto-refetch on a timer, tire pressure & compound, converter/trans temp, throttle-stop timers, fuel specific gravity, lane-by-lane track prep history, and per-car profiles with cloud sync.