Wednesday, May 30, 2007

Petrol vs diesel at Le Mans

My compadres over at the Ten-Tenths sportscar forum are all a-twitter at the moment about equivalency formulae between diesel and petrol Le Mans Prototype cars. I've tried to stay out of the discussion because it seems like one of those threads where no-one really hears what anyone else is saying and it all ends up being a bit pointless.

But it's an important issue that impacts the future of Le Mans sportscar racing. The perceived problem is that the current rules format favours diesel-powered cars unfairly. In theory, ACO Le Mans rules are supposed to offer teams and manufacturers the option of running different fuels, none of which offer an advantage over any other, thus encouraging innovation and use of alternative fuel technologies.

In reality, there are two teams running cars with diesel engines, and both those teams appear to be running significantly faster than any of their rivals. As a result, many people are saying that the rules favour diesels. The one point I made on the aforementioned forum thread was that it just so happens that the only two teams running diesels are the only two Le Mans entrants in the prototype class who can effectively be considered "manufacturers".

So is the apparent pace of the Peugeot and Audi diesels down to their engine or their HUGE AMOUNT OF FINANCIAL RESOURCES??? This is a question that will be answered in 2008 (maybe) and 2009 (certainly), when Acura step up their ALMS prototype project to the LMP1 class. It will be the first time EVER that a factory Audi will have been challenged by a petrol-powered prototype from a manufacturer with a legitimate shot at winning Le Mans. Until then, Audi and Peugeot's closest rivals will be privateers such as Pescarolo, Creation, Zytek and Courage, all of which run petrol engines and all of which operate on a fraction of the budget of the two big diesel teams. It's like comparing apples and oranges, something that some of my friends over at 10/10ths seem to be missing.

The elephant in the room here is Porsche. Despite running very close to Audi in the ALMS all year, they believe that the current engine equivalency formulae in LMP1 are so tilted in the favour of diesels that they are considering delaying their entry into LMP1. Personally I think Porsche should suck it up and get on with the job. If it becomes clear that petrol engines are being unfairly legislated against, I'm sure the ACO will make adjustments.

The numbers seem to indicate that any adjustment is either unnecessary or would need to be tiny. Last year, Pescarolo ran a 3:30 on the Le Mans test weekend, and a 3:32 in qualifying, with Audi doing vice versa. So performance was close prior to the race itself. In the race, Pescarolo lost by four laps. Audi's 27 stops gave a total of 2700 litres of fuel taken onboard. In 2007, Audi's fuel tank will go from 100 litres down to 81 litres, giving 34 pitstops. So if both teams run the same pace with the same fuel economy this year, Audi's seven extra stops will cost them an extra 11 minutes, which is equal to three laps. What this means is that the change in fuel tank size has gone a long way to levelling the playing field, and that really it seems as though petrol performance is only about 0.25% below what it should be (at Le Mans at least) in order to produce a straight fight against diesels.

We'll know in 18 days. I'll be watching very carefully from my pitlane grandstand seat how many laps diesel teams are getting on one stint versus what the petrol cars get.

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