Wednesday, 4 June 2014

Le Mans Test Day - more than sector times

In the ‘old’ days, when I first went to Le Mans, it was all about straight line speed. The Mulsanne straight, more than 6km long, represented very nearly half of the total lap length. Aerodynamics were important, of course, but minimising drag down that long straight was absolutely vital, even if it meant that the car was a bit lively through the Porsche Curves.

Then the chicanes were installed in 1990, and no-one was sure quite what to do. Porsche 962 entries were numerous, entered by experts like Reinhold Joest and Richard Lloyd. The factory recommended they be run in long-tail trim, but some privateers (most notably Walter Brun) ran short-tail, high downforce configuration. Those who were there will remember that short-tail proved the way to go.

These days, Toyota and Audi have had two aerodynamic configurations: one specifically for Le Mans and the other more suitable for the more typical circuits of the rest of the season. But Toyota demonstrated at the six hours of Spa that the ‘Le Mans’ configuration is really rather good at Spa as well, leaving Audi (run by Joest, coincidentally) rather scratching their heads.

Since the data from the Test Day has now been issued, I am trying to work out what it all means. Looking purely at the fast laps that were set by Marco Bonanomi in the no. 3 Audi in the morning session, the fastest lap of the session at 3m 23.799s included a sector 2 time of 1m 18.480s. Sector 2 is from the beginning to the end of the Mulsanne straight, if you are not familiar with the layout of the track, so really represents the ‘power’ element of the circuit. On that same fast lap, Marco’s time through the Porsche curves was 16.321s.

To put these two times into context, the fastest time through sector 2 in the morning session was 1m 17.667s and the best time through the Porsche Curves was 16.156s, so Bonanomi was around 1% off the best time in both the ‘power’ element and the ‘handling’ element of the circuit. So where did the time come from?

Well, fairly obviously, it came in sectors 1 and 3. But it didn't come in the ‘tight bits’ of sector 3; in both the Porsche Curves and the Ford Chicane, the Audi was not the quickest. So the advantage must have come from the Dunlop Chicane up to Tertre Rouge and from Mulsanne Corner back through Indianapolis and Arnage, to the start of the Porsche curves.

Traffic may have played a part - Bonanomi overtook five cars on that fast lap - and we cannot really know what fuel was being used, but it would certainly seem that there was more going on there than met the eye.

In the afternoon session, of course, Toyota established its position as the fastest car; a situation to which we have become accustomed this year. Right at the beginning of the session, Sebastien Buemi went out in the no. 8 car and set a series of fast laps. In two five lap stints, he set three laps under 3m 24s, with an outright best of the day of 3m 23.014s. Again, though, it is interesting to note that Buemi's best time through sector 1 on these laps were not as quick (by a margin of more than 1%) as those achieved by Davidson in the same car, later on. Down the Mulsanne though, and back through sector 3, Buemi was practically as quick as the best - to within a few tenths, at least.

Again though, the time does not seem to be coming from the Porsche Curves nor the Ford Chicane: Buemi’s time through the Porsche curves on his fastest lap was 16.034s; his time through the Ford Chicane 6.068s. Compare these times to the fastest times in those specific sectors in the afternoon session: 15.709s by Kristensen in Porsche Curves and 6.011s in the Ford Chicane (by Buemi on a slower lap earlier in his stint). So it must be the long straight(ish) bits before and after Arnage where the Toyota was making up time.

I’m aware that all this analysis doesn’t really prove anything conclusively. But it seems to me that we have moved into an era where the hybrid power units are delivering power in a different way from what we are used to; where driver techniques have changed so that time is made up differently.

Toyota, with over 100,000 hybrid road car drivers in the UK alone, seemed to have the Test Day nailed. Whether Porsche and Audi will be able to learn and adapt by the time the tricolor waves on Saturday afternoon next week, remains to be seen.


  1. Hi Paul, Nice article. Is it possible that some of the time is coming from improved acceleration as the Audi and the Toyota now aceleate with both front and rear axles without the disadvantage of the "not under" 120km/h rule of last year.

    The reason I say this is that the 2 sections you mention both have extreme braking from very high speeds which would fill the ERS systems nicely for the hard acceleration out of Mulsanne and Arnage

    I think its clear though 2014 LM24Hr is going to be great

    1. I wonder what the impact of. Safety car or even a yellow flag will have this year. The different energy recovery systems will store energy for different lengths of time before degradation and importantly, will not all recover the same relative amounts under these specific conditions. In a close race, this really could be the critical difference. I guess everyone is learning this year,engineers, drivers and fans alike.