Standing starts — the data behind the Dual Clutch article

Rudskogen Motorsenter — temperature sweep

274 measured standing starts across 26 consecutive track temperatures, every one a full sweep of bite points 41–49. One car, one setup, one gear stack, one grid box, one time of day, clear sky, 0% humidity, clean track surface — only the temperature was changed. iRacing sets weather in whole degrees Fahrenheit and displays a rounded Celsius value, so Fahrenheit is the step that actually moved; the track surface sits exactly 1°F below the air with the sun down.

Every launch, bite point by bite point

The lowest RPM reached at each bite point, at each temperature. The highlighted cell in a row is the bite point that produced that temperature's fastest launch.

Track	Air	Launches	41	42	43	44	45	46	47	48	49	Fastest	Its lowest RPM	Cost of the heat
17.8°C (64°F)	18.3°C	19	1,000	1,147	1,301	1,507	1,804	2,265	3,112	4,142	4,869	46	2,266	—
18.3°C (65°F)	18.9°C	9	1,077	1,238	1,431	1,687	2,083	2,810	3,803	4,659	5,251	46	2,810	+6 ms
18.9°C (66°F)	19.4°C	9	1,940	2,586	3,467	4,433	5,099	5,540	5,932	6,251	6,512	42	2,586	+8 ms
19.4°C (67°F)	20.0°C	22	1,571	1,894	2,414	3,350	4,345	5,031	5,493	5,896	6,223	43	2,415	+9 ms
20.0°C (68°F)	20.6°C	9	1,532	1,842	2,332	3,217	4,237	4,939	5,442	5,855	6,189	43	2,332	+13 ms
20.6°C (69°F)	21.1°C	9	1,185	1,343	1,569	1,900	2,420	3,360	4,353	5,037	5,499	45	2,420	+14 ms
21.1°C (70°F)	21.7°C	9	1,020	1,161	1,318	1,544	1,858	2,357	3,262	4,275	4,974	46	2,357	+18 ms
21.7°C (71°F)	22.2°C	12	1,194	1,383	1,631	1,986	2,658	3,591	4,524	5,171	5,598	45	2,657	+21 ms
22.2°C (72°F)	22.8°C	9	965	1,099	1,249	1,437	1,704	2,113	2,856	3,869	4,703	47	2,856	+25 ms
22.8°C (73°F)	23.3°C	9	910	1,018	1,177	1,335	1,562	1,891	2,416	3,352	4,351	47	2,416	+27 ms
23.3°C (74°F)	23.9°C	13	1,111	1,267	1,471	1,744	2,172	2,965	3,991	4,781	5,337	45	2,173	+32 ms
23.9°C (75°F)	24.4°C	9	1,413	1,669	2,056	2,767	3,751	4,631	5,238	5,666	6,034	44	2,767	+34 ms
24.4°C (76°F)	25.0°C	9	1,623	1,985	2,657	3,593	4,525	5,173	5,602	5,983	6,295	43	2,657	+35 ms
25.0°C (77°F)	25.6°C	9	906	1,016	1,174	1,331	1,557	1,885	2,403	3,342	4,344	47	2,403	+35 ms
25.6°C (78°F)	26.1°C	14	1,126	1,271	1,470	1,753	2,189	2,998	4,033	4,807	5,353	45	2,189	+42 ms
26.1°C (79°F)	26.7°C	9	985	1,118	1,265	1,464	1,751	2,179	2,974	4,007	4,792	46	2,179	+45 ms
26.7°C (80°F)	27.2°C	9	759	935	1,036	1,183	1,375	1,610	1,964	2,622	3,538	48	2,622	+45 ms
27.2°C (81°F)	27.8°C	14	1,788	2,242	3,084	4,125	4,865	5,396	5,821	6,162	6,436	42	2,241	+52 ms
27.8°C (82°F)	28.3°C	9	1,011	1,149	1,298	1,517	1,821	2,299	3,175	4,207	4,927	46	2,299	+52 ms
28.3°C (83°F)	28.9°C	9	1,269	1,466	1,746	2,178	2,982	4,019	4,801	5,352	5,783	44	2,178	+57 ms
28.9°C (84°F)	29.4°C	9	1,166	1,322	1,548	1,871	2,384	3,321	4,333	5,026	5,498	45	2,384	+58 ms
29.4°C (85°F)	30.0°C	9	930	1,029	1,180	1,362	1,589	1,936	2,595	3,488	4,453	47	2,595	+59 ms
30.0°C (86°F)	30.6°C	9	749	880	998	1,145	1,297	1,500	1,803	2,275	3,140	48	2,275	+64 ms
30.6°C (87°F)	31.1°C	9	1,431	1,694	2,087	2,832	3,850	4,696	5,283	5,718	6,075	44	2,832	+67 ms
31.1°C (88°F)	31.7°C	9	1,200	1,387	1,648	2,014	2,701	3,686	4,588	5,218	5,648	45	2,701	+69 ms
31.7°C (89°F)	32.2°C	9	862	970	1,095	1,252	1,451	1,720	2,141	2,921	3,950	47	2,141	+74 ms

Each cell is the lowest engine RPM reached in first gear after the clutch release, at that bite point and temperature. Repeated launches at the same bite point and temperature agree within about 5 RPM, so these are single stable values rather than averages of noise.

The fastest dual clutch bite point at each track temperature, jumping between 42 and 48 with no trend — Dots are the fastest bite point measured at each degree; the line is the bite point that would land the engine at 2400 RPM, interpolated between the two measured bite points either side of it. Neighbouring degrees can want bite points five clicks apart, and there is no trend to interpolate along.

Milliseconds lost against the coldest run, rising steadily with track temperature — The best launch available at each temperature, against the best launch of the coldest run, over the same 83 metres. Unlike the setting, this one is orderly: every step up in temperature costs a little more, with no exceptions.

Lowest RPM at the fastest bite point, landing in a narrow band at every temperature — Whatever bite point won, it produced the same thing: an engine speed of 2,141–2,856 RPM. This is the number to aim at, and it is why the bite point itself is not worth memorising.

The cost of dialling one fixed bite point

If you always use the same value regardless of conditions, this is what it costs against the optimal bite point for the day, measured over the 83 metres to the end of first gear, across all 26 temperatures.

Bite point	Average	Median	Worst
41	1.58 m	1.71 m	3.13 m
42	1.15 m	1.23 m	2.18 m
43	0.83 m	0.85 m	1.84 m
44	0.72 m	0.73 m	2.15 m
45	0.90 m	0.53 m	4.59 m
46	1.55 m	0.60 m	7.46 m
47	2.69 m	1.10 m	10.59 m
48	4.55 m	3.43 m	13.95 m
49	7.10 m	6.14 m	17.51 m

44 is the best fixed bite point. Too soft costs more than too aggressive: 2.69 m on average three clicks high, 1.58 m three clicks low.

Earlier work — one run at a time

These runs came before the sweep above and focused on changing multiple parameters. They are kept for the record, but read them in that light: the sweep showed that a single unnoticed condition can move the best setting further than the effects these runs set out to measure.

Virginia International Raceway — North course

16 runs, 95 measured standing starts, with the virginia.sto setup (baseline_wet.sto for the wet runs). Condition-controlled protocol: a baseline run (Tall gear stack, 25°C track, 0% humidity, dry, clean track surface, 17 L), then one condition changed per run. All launches from the same grid box.

	Conditions						Best settings
Run	Gear stack	Track temp	Humidity	Wetness	Track usage	Fuel	Fastest	2nd fastest	3rd fastest	Settings tested
07-17 20:10	Tall	50.6°C	0%	dry	clean	17 L	43 · 5.300s · 2207	44 +0.004 · 3017	42 +0.011 · 1762	40–46
07-17 20:16	Tall	50.6°C	0%	dry	maximum usage	17 L	43 · 5.298s · 2208	44 +0.005 · 3022	42 +0.012 · 1762	41–45
07-17 20:19	Tall	25°C	0%	dry	maximum usage	17 L	45 · 5.230s · 2262	46 +0.005 · 3092	44 +0.010 · 1807	41–48
07-17 20:27	Tall	25°C	0%	dry	clean	17 L	45 · 5.228s · 2261	46 +0.007 · 3093	44 +0.011 · 1806	30, 35, 40, 42, 43, 44, 45, 46, 47, 50
07-17 20:33	Tall	25°C	100%	dry	clean	17 L	44 · 5.293s · 2636	43 +0.005 · 1974	42 +0.019 · 1614	41–46
07-17 20:38	Standard	25°C	0%	dry	clean	17 L	45 · 5.455s · 2241	46 +0.005 · 3068	43 +0.026 · 1494	43–47
07-17 20:40	Short	25°C	0%	dry	clean	17 L	44 · 4.227s · 2160	45 +0.002 · 2633	43 +0.005 · 1833	42–46
07-17 20:44	Very Tall	25°C	0%	dry	clean	17 L	45 · 5.342s · 2262	46 +0.006 · 3093	44 +0.011 · 1808	43–47
07-17 20:47	Tall	25°C	0%	dry	clean	3 L	45 · 5.182s · 2296	46 +0.008 · 3124	44 +0.009 · 1834	43–47
07-17 20:50	Tall	25°C	0%	dry	clean	22 L	45 · 5.244s · 2252	46 +0.006 · 3086	44 +0.012 · 1796	43–47
07-17 20:54	Tall	17.8°C	0%	very lightly wet	clean	17 L	45 · 5.229s · 2261	46 +0.007 · 3101	44 +0.011 · 1807	43–47
07-17 20:58	Tall	17.2°C	0%	lightly wet	clean	17 L	45 · 5.232s · 2261	46 +0.007 · 3112	44 +0.010 · 1807	42–47
07-17 21:01	Tall	17.2°C	0%	moderately wet	clean	17 L	45 · 5.232s · 2261	46 +0.007 · 3115	44 +0.011 · 1806	42–47
07-17 21:05	Tall	17.2°C	0%	very wet	clean	17 L	45 · 5.236s · 2261	46 +0.006 · 3116	44 +0.010 · 1807	42–47
07-17 21:09	Tall	16.7°C	0%	extremely wet	clean	17 L	45 · 5.239s · 2259	46 +0.007 · 3118	44 +0.011 · 1805	43–47
07-17 21:13	Tall	18.3°C	0%	dry	clean	17 L	45 · 5.228s · 2262	46 +0.006 · 3094	43 +0.024 · 1512	43–47

Mosport (Canadian Tire Motorsport Park)

4 runs, 28 measured standing starts, all with the mosport.sto setup.

	Conditions						Best settings
Run	Gear stack	Track temp	Humidity	Wetness	Track usage	Fuel	Fastest	2nd fastest	3rd fastest	Settings tested
06-27 07:04	Tall	38.3°C	35%	dry	maximum usage	16 L	48 · 5.520s · 2139	49 +0.004 · 2489	47 +0.013 · 1712	45–55
06-27 07:13	Tall	38.3°C	35%	dry	maximum usage	16 L	48 · 5.516s · 2144	49 +0.001 · 2917	47 +0.013 · 1715	45–50
06-27 07:22	Tall	38.3°C	35%	dry	maximum usage	16 L	48 · 5.508s · 2149	49 +0.001 · 2919	47 +0.013 · 1721	47–50
06-27 07:26	Tall	38.3°C	35%	dry	maximum usage	16 L	48 · 5.519s · 2140	49 +0.001 · 2913	47 +0.014 · 1713	47–50

Reading the min RPM column: the minimum RPM identifies the setting error without any timing. The ideal is around 2200–2800 RPM; above ~3000 the engagement is too soft (setting too high); below ~1800 it is too aggressive (setting too low). Near 750 the anti-stall has intervened and the launch loses seconds.

Repeatability / noise floor: identical settings repeat within a run to 0–2 ms, and a baseline rerun two hours later reproduced the original to 2 ms — podium places closer than ~5 ms are effectively ties.

Large deviations (from the Virginia 20:27 sweep, settings 30–50): setting 50 costs +0.319 s over 1st gear alone, setting 40 +0.060 s, settings 30–35 +0.11–0.13 s.

Wet runs are also colder (rain cools the track), so two conditions move at once; the late dry run at 18°C confirms 45 remains fastest on a cool dry track at Virginia.

Cross-track: the winning setting differs (Mosport is fastest at ~48 where Virginia is fastest at 45) but the winning minimum-RPM band is the same everywhere — which is why we recommend tuning by the minimum RPM, not by a remembered number. More tracks and conditions to come.