Automobile Club de l’Ouest Changes Le Mans Regulations

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The performances of the cars will be adjusted for the Le Mans 24 Hours

Following the Spa-Francorchamps 1000 kms (7th May), the second round of the Intercontinental Le Mans Cup, the Automobile Club de l’Ouest has decided to adjust performances between cars in the same category as foreseen by the regulations before the Le Mans 24 Hours (11th-12th June).

Vincent Beaumesnil, the Automobile Club de l’Ouest’s sports manager, explains the reasons in a question and answer session.

“Vincent, why has the Automobile Club de l’Ouest decided to adjust performances between cars in the same category?”

VB: “2011 has seen the introduction of new technical regulations. If, in theory, things were evaluated beforehand, it is important to analyze what really happens on the track. When the 2011 petrol/diesel equivalences were announced last year, they received almost unanimous approval. Teams entering petrol-powered cars said that the new regulations gave this type of engine a real boost compared to the 2010 equivalences. To evaluate the results on the track, the ACO bases its calculations on the performances of the cars in the race only: qualifying and free practice don’t come into the equation. Performance is an overall concept that takes into account all the factors that can influence the results of a car. Thus, not only lap times, but also everything that contributes to the final result, power, torque, aerodynamics, cornering speeds, pit stop times, fuel consumption tyres etc, are evaluated.”

“Why have these adjustments been introduced after the Spa-Francorchamps 1000 kms and not before?”

VB: “In the regulations it was laid down that the ACO would analyze the situation after two races. Thus, it was necessary to wait for the Spa-Francorchamps 1000 kms (second round of the ILMC) to have two areas for comparison. The Sebring 12-Hours race alone would not have been enough. In addition, all the types of engine technology such as diesel power did not enter for the Le Castellet 6 Hours (LMS event) or the Long Beach race (ALMS) to enable us to calculate all the adjustments necessary. By making these adjustments after the Spa-Francorchamps race, the ACO has accumulated enough data, and it gives the teams sufficient time to carry out these modifications before the Le Mans 24 Hours.”

ACO annual press conference: ACO Sport Director Vincent Beaumesnil
ACO annual press conference: ACO Sport Director Vincent Beaumesnil

Photo by: Eric Gilbert

“What data were taken into account?”

VB: “All the factors that determine the performance of a car, which the ACO can then use to adjust performance.”

• Temps au tour (Lap Time)
• Temps sectoriels (Split Time)
• Phases d’accélération (Phases of acceleration)
• Vitesse de pointe (Top speed)
• Autonomie / Consommation (Autonomy/Consumption)
• Temps de remplissage du réservoir (Time of filling of the tank)
• Consommation de pneus (Consumption of tires)

“What decisions has the ACO taken?”

VB: “They have to be explained category by category.

“In LM P1, (Le Mans prototype 1 : Audi R18, Peugeot 908, Pescarolo-Judd, Rebellion-Toyota, Aston Martin AMR-ONE etc).”

• “Let’s look at article 19 of the technical regulations, first of all: an analysis of track data (including the timing measuring acceleration - confidential data not given to the entrants at Spa) and the information collected by the ACO data acquisition systems have enabled the club to define a compensated engine performance figure between diesel and petrol technologies. In this context, only the engine performance has been assessed and taken into account, not the lap times. On this basis the ACO has applied a modification to the fuel refuelling nozzle (+ 10 mm for petrol-engined cars, - 3 mm for diesel-powered ones).”

• “We then took into account Article 1.3 of the ACO sporting regulations, usually known as the 2% rule. According to this article only the cars that have raced in two events can take advantage of the adjustment that allows the performance level of the quickest car in a slower technology (petrol in this case), to be tweaked by 2% maximum compared to that of the quickest car in a faster technology (diesel). This additional adjustment complements article 19 where necessary (if the adjustment of article 19 does not give the 2% gap then an addition is granted). In the present case: + 0.3 mm for the engine air restrictor and - 10 kilos for petrol-engined cars eligible for this modification. Or + 0.5 mm in the case of a car whose weight cannot be changed.”

Can you explain each of these measures?

VB: “Let’s start with the modifications to the refuelling nozzle, particularly the slide, which can be adjusted in a consistent fashion. Changing a simple component in the hose can increase the difference in refuelling times by over twenty-two seconds, the equivalent of two seconds a lap over the Le Mans 24-Hours race. It’s a simple and inexpensive measure for the teams. But don’t be misled, it’s not because the diesels will take longer to refuel that they will use more fuel than the petrol-engined cars. The maximum quantity of fuel on board is 65 litres for the diesels and 75 litres for the petrol-engined cars. The number of laps between two refuelling stops should be the same for petrol and diesel engines. The latter should spend more time at their pits because the fuel flow will be slower.”

“Weight of the cars (-10 kgs) and air restrictors (+ 0.3 mm or +.5 mm). These relatively low figures are an addition to achieve the aims defined by the study of the performance data. Certain manufacturers were unable to exceed these figures (because of engines already at the limit of their development t or due to the tricky problem of weight reduction, particularly complex with no ballast), and the ACO did not want to create an imbalance between teams.”

“The modification to the fuel tank for petrol-engined cars was also excluded as it implied too big a job for some teams.”

“What results are you hoping to achieve on the Le Mans circuit?”

VB: “Overall, these adjustments will be more noticeable on the distance covered at the finish, rather than the seconds gained over a lap as we’re acting mainly on the pit stop times. It may translate into a gain of four or five laps during the Le Mans 24 Hours.”

“Why have you modified the petrol-engined cars in priority?”

VB: “That’s what’s laid down in the ACO regulations which state: “the cars with the slowest technology will be adjusted.”

"Why have you reduced the weight of the Oreca-entered Peugeot 908 HDi FAP (2010 car) by fifteen kilos?”

VB: “Article 19 also provides the possibility of adjusting the performances of the 2010 LM P1s compared to the 2011 cars while giving the latter a slight advantage. As the 908 HDi FAP is just outside the 2% bracket in relation to the quickest 2011 diesels, this weight reduction is easy to achieve as the car already carries thirty kilos of ballast, and it helps reduce what is a big gap.”

What about the LM P2s (Le Mans Protoptype 2): Oreca–Nissan, Honda Performance Development, OAK-Pescarolo etc).”

VB: “As the ACO gave an undertaking that all cars not meeting the capped price ceiling should not be quicker than those complying with the 2011 regs (max. price: 345 000 euros), an adjustment has been made to the refuelling nozzle (+ 3.5 mm for the 2011 cars). Concerning the engines we’ve seen that the Juud seems slightly down on performance, so we’ve adjusted its power as we did for the Honda Performance Development engine.”

“And finally, what about the LM GTEs (Le Mans Endurance Grand Touring Cars): Lotus Evora, Ferrari F 458 Italia, BMW M3, Corvette, Porsche)?”

VB: “Article 19 of the LM GTE technical regs (performance adjustments) has been applied mainly to the Lotus Evora, which had a difficult debut, and the Doran Ford GT to which we’ve applied the performance balance it has in the United States.”

-source: aco

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Series ALMS , LEMANS , ELMS
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