Thoughts From Le Castellet
Inspector Truswell Examines The Evidence

After the race at Paul Ricard, it was suggested to me that Bart Hayden, of Rebellion Racing, was disappointed that the #13 car of Jean-Christophe Boullion and Andrea Bellichi had been unable to catch up with the winning Pescarolo. Despite problems early in the race with a door that would not shut properly, Rebellion hoped that their 2011-specification, Toyota-engined Lola would be able to close the gap on the Pescarolo, which was running to the ACO’s ‘grandfather’ rules, enabling cars conforming to 2010 regulations to compete in this year’s Le Mans Series, but with smaller restrictors to equalise their performance. In fact, the LMP1 regulations state that the 2011 cars will have “a small advantage” over the older cars, in order to encourage teams towards the new rulebook. Of course, the Pescarolo is more of a great-grandfather really, having originally appeared (as a chassis manufactured in its own right) in 2005.

So I thought I would take a look at the data and see if there was any evidence either that the ACO’s sums were right, or that Bart Hayden’s disappointment could be assuaged.

To start off with, here is a graph showing the gap between the Pescarolo #16 and the Lola #13 over the course of the race.

I am looking particularly at the first ninety minutes of the race, to the left of the thick blue line. In this period, the Lola pits three times, on laps 13, 17 and 33, whereas the Pescarolo has only one stop, on lap 28. At this point in the race, the Rebellion car had spent 3m 36s in the pits, compared to the Pescarolo’s 58.7s. No surprise, then, that the graph shows that Tinseau’s lead over Boullion is 2½ minutes.

The question that I want to try to answer though, is whether that gap was too large for the Rebellion team to be able to recover in the remaining 4½ hours, had all other factors remained equal.

In the following graph, I have extended the downward sloping lines from laps 21 to 31 and from 34 to 54. The first of these seems to indicate that the Rebellion Lola could have taken the lead just after the four hour mark on around lap 125. However, following the second pit stop on lap 33, it looks less likely.

However, note the impact of the final safety car period, from lap 103 to 105. Although both the Pescarolo and the Rebellion Lola stopped during this period, once the safety car had gone in, the gap between the two leading cars had reduced by more than a minute. This impact, applied to the projected plan of the Rebellion Lola in the second half of the race, would also have enabled it to win the race.

The other thing which this data suggests is that the pace advantage that the Rebellion Lola appeared to show in the early stages is not so noticeable in the later stages. I wonder if Bart Hayden is drawing to the attention of Andrea Bellichi the fact that the Italian’s driving shifts (from lap 55 to 103 and from lap 163 to the end), do not seem to have the same impact on the gap as those of Jean-Christophe Boullion?

The talking point of the paddock (apart from the chaos at the start) was the relative performances of the various LMP2 entrants. In particular, it was alleged (pretty vocally, from a number of corners) that the turbo-charged Honda Performance Development cars were not giving as much power as the normally-aspirated cars. Having said that, in the race, the Strakka Racing HPD was well up the order and was leading the LMP2 class from lap 99 to lap 139, until Nick Leventis took over the driving duties.

In terms of top speed, the official timing (by Al Kamel Systems) gave the following top speeds (measured at the end of the Mistral Straight).

Now I am extremely nervous about top speed figures, as they always seem to be misleading, but I give them in order for you to draw your own conclusions.

Perhaps more interesting are the best sector times:

But even this data is inconclusive. One of the attractions of endurance racing, to me, is that not everything is equal. Different cars have different strengths and weaknesses; there are two or three drivers in each car, each of whom have a different skill set; different teams excel under different conditions. What makes endurance racing interesting is not watching cars battling nose-to-tail or side-by-side over the course of six or more hours, (although some people seem to disagree). The fascination of endurance racing is watching cars with a speed disadvantage overcoming that disadvantage, and winning - sometimes, not always - against the odds. Audi’s wins at Le Mans in 2010 and 2008 were such examples.

It would certainly seem that the HPDs were not as quick at any point as most of their Nissan or Judd-engined rivals. And in terms of pit stops, only the RML HPD and the class-winning Greaves teams managed the race on just six pit-stops (the same as the race-winning Pescarolo). The rest of the P2 field all completed the race on seven stops.

In the following table, I open up the complexity of the matter, a little. Taking the period of the race from the withdrawal of the safety car with half an hour of the race gone, up to the point, about four hours later, when the Strakka entry lost the lead of the class, each of the top four LMP2 teams completed five stints, the length and average lap time for which are shown.

In order to make it a fair comparison, I ignore the time spent in the pits and also the time spent behind the safety car, during the fourth stint. Now this is where the maths gets a bit dodgy, but if you take the difference between the fastest and the slowest stint for each car, you get:

..which I think shows why the Strakka HPD led the class for so long, despite being ‘slower’. If the ACO is going to meddle with the technical regulations either at Spa or at Le Mans, it ought, I suggest, to consider all the aspects of performance balancing very carefully indeed.

Paul Truswell