Quarter-mile weight sensitivity
Hold engine power constant and compare an empirical ET model at different race weights. Change an input to explore the relationship.
Input parameters
Set your values below. The table updates automatically.
Comparison results
Model sensitivity only. No launch, traction, aerodynamic or weather corrections.
| Race weight (lb) | Race weight (kg) | Empirical ET (s) |
|---|---|---|
| 1,500 | 680.39 | 9.05 |
| 2,000 | 907.18 | 9.96 |
| 2,500 | 1,133.98 | 10.73 |
| 3,000 | 1,360.78 | 11.40 |
| 3,200 | 1,451.5 | 11.65 |
| 3,500 | 1,587.57 | 12.00 |
| 4,000 | 1,814.37 | 12.55 |
| 4,500 | 2,041.17 | 13.05 |
How this table is calculated
ET = 5.825 × (weight_lb / HP)^(1/3)Rows use the same assumptions while varying the value in the first column. Input-unit controls change the units used to enter values; column headers always state the output units.
How to read this comparison
Power stays fixed while race-ready weight changes. The ET column comes from the stated empirical cube-root model. Compare rows as model sensitivity rather than guaranteed time-slip outcomes.
A worked example with the initial inputs
At the initial 400 hp, the 3,200 lb row gives ET = 5.825 × (3,200/400)^(1/3). The quotient is 8 and its cube root is 2, so the result is 11.65 seconds.
The live table changes when you edit its controls.
Use the interactive calculator to explore more scenarios, units and relevant inputs.
Frequently asked questions
Does the table account for better traction after a weight change?
No. Only the entered model weight changes between rows. Launch, gearing, aerodynamic behavior, weather and traction are not simulated.
Why do input controls and column headers show different units?
The unit toggle changes how you enter dimensional inputs. Each output column keeps its stated unit so you can compare values consistently. Read the column header before copying a result.
Understand the method in more detail
Source and assumptions
Hale coefficient model: ET constant 5.825 and speed constant 234. Lucius documents the formulas and compares them with road-test data. These are empirical relationships, not physical laws or calibrated vehicle predictions.
Jeff Lucius / Stealth 316 — Quarter-mile formulas and original regression analysisRead the calculation methodology for model scope, unit conventions and review status.