The Automobile Club de l'Ouest (ACO), which sanctions the 24 Hours of Le Mans and provides the basis for the rules used in the American Le Mans Series, has just published its rules changes for 2010. The updates for next year are mainly targeted at tightening competition while maintaining series stability. Because sports car racing, unlike many other forms, allows an array of very different machines with different powertrains, the rules have to provide some means of equivalency to provide an even playing field.

To that end, the ACO is again making some adjustments to the rules for the diesel-powered cars that have dominated Le Mans for the past four years. Next year, the diesels from Peugeot and Audi (and anyone else who might opt to run one) will have to carry an extra 30 kg of ballast relative to gas-powered cars, bringing their minimum weight to 930 kg. Since power output is in part a function of how much air gets into the engine, the air restrictors for diesels will be reduced 2.1 percent in size and maximum turbo boost is being cut from 2.75 BAR to 2.59 BAR. Conversely, gas engines get 5 percent larger restrictors. The rules don't specifically say anything about hybrids at this point because ACO is still letting those cars run unclassified until some performance data is accumulated.

[Source: Automobile Club de l'Ouest]

The ACO unveils the 2010 Le Mans regulations

In accordance with the undertakings given after this year's Le Mans 24 Hours, and to enable manufacturers to have more time to prepare for the coming season, the ACO, today, unveils the 2010 Le Mans regulations. An update inspired by two main criteria: stability and consultation.

Vincent Beaumesnil, the ACO Sports Manager, says in the interview on page 4: "Regulations have to evolve from one year to the next to adapt to the context". The evolution follows on from the meeting with all the manufacturers on 29th-30th June at Le Mans. It is the result of a study carried out by the ACO technical directors and consultants in the light of the analysis of a lot of data - gathered by the ACO and supplied by the manufacturers - which was then validated by the ACO Sports Committee.

"In an unfavorable economic context, the idea was to modify the cars as little as possible, continues Vincent. All entrants want to be able to use their current cars in 2010, and possibly in 2011 and beyond*. It was necessary to make a few clarifications and to modify certain points in the regulations to prevent some entrants from investing in solutions that we consider too extreme, and which go against the aims we have set ourselves – to keep the cars' lap speeds above 3m 30s at Le Mans".

The other aim of the text published today is to adjust the performances between LM P1 cars with diesel engines, petrol engines or engines coming from a car homologated in LM GT1, of which the Aston Martin is the main example (see the table of the new engine equivalences on page 2).

Here are the details of this update that apply mainly to the technical regulations, which Messrs Rémy Brouard, the ACO General Manager, Pierre Fillon, Vice President and Vincent Beaumesnil, Sports Manager, will talk about this evening during a press briefing at 18H00 in the press room at the Nürburgring 1.000kms, the 4th round of the 2009 Le Mans Series.

*In particular, entrants who already have or who are thinking of buying an LM P2, which will become eligible
in LM P1 with a few modifications from 2011 onwards.

1- LM P1 & LM P2 bodywork:
At the rear:
Closing of the part behind the rear wheels. The use of grills or fairings to cover the rear wheel above the axis of the axle will no longer be allowed. The bodywork must be closed in this area and must carry the rear lights, rear stop lights and indicators.

On the sides:
Bodywork located at the rear of the axis of the rear wheels and above the reference plate must form a smooth, continuous, unbroken surface of convex form only, without cuts. It must not be set back more than 100mm in relation to the width of the bodywork at the axis of the rear axle (measured horizontally).

At the front:
Confirmation within 15 days of the aerodynamic definition of the front of the cars. It is currently under study and consultation with the manufacturers taking into account the technical feasibility and cost issues.

2- LM P1 engines: (figures for a given cubic capoacity)

These adjustments will be applied proportionally to all cubic capacities in the 2010 technical regulations answer several objectives:
- Guarantee technical equality between the different technologies.
- Each technology used should allow each entrant to be competitive. .../...

Engine equivalences 2009 2010 Variation (air restrictor surface, or supercharger pressure) 2009/2010
(5.2 to 5.5l)
(for 2 restrictors) 37.9 mm 37.5 mm - 2.1%
Supercharger pressure 2750 mbar 2590 mbar -5.8%
Restrictor advantage
for closed cars 0.4 mm 0.3 mm
(5.5 to 6l )
(for 2 restrictors) 32.5 mm 33.3 mm + 5%
Restrictor advantage
for closed cars 0.3 mm 0.3 mm

GT1 engine
(de 5.5 à 6.l)
(for 2 restrictors)
32.7 mm 33.3 mm
+ 2.4%
Advantage engine
restrictor over
8 cylinders
0.4 mm 0.2 mm

Restrictor advantage
for closed cars
0.3 mm 0.3 mm

GT1 engine regulations in LM P1:

GT1 engines installed in LM P1s must comply with article 5 of the LM GT1 regulations (see: with the exception of:
􏰀 Accelerator (free)
􏰀 Direct injection (modifications to the cylinder heads must be approved by the ACO)
􏰀 Air box (volume free)

Use of engines in the Le Mans Series:

At present the regulations oblige entrants to use the same engine for 2 consecutive races minimum. In 2010, 3 sealed engines can be used freely during the season.

The number of engines (2) allowed for the Le Mans 24-Hours week remains unchanged.

3- Weight of the cars :
The minimum weight of the LM P1 diesel cars is increased to 930 kilos (30 kilos of ballast cancelled). The minimum weight of the other categories remains unchanged

4- LM GT :
In accordance with the announcement made during the Le Mans 24 Hours Press Conference, confirmation of the ACO's position on the GT1 category at the end of September. For the GT 2 category, the 2009 ACO regulations will be applied in 2010.

Sporting regulations innovations
Mechanics carrying out wheel changes will be identified by arm bands supplied by the organisation. Four arm bands will be allocated per car. The number of mechanics authorised in the work space remains unchanged (2).
For the Le Mans Series, the maximum driving time of 4 hours per driver in a race will be reconsidered.
The selection criteria for the Le Mans 24 Hours will be reinforced on the basis of two main principals:
1. Entrants having raced in a full Le Mans Series (2009 ALMS, LMS or the Asian Le Mans Series) on a regular basis will be favoured.
2. Applicants presenting evident technological advantages will also be favoured by the ACO.

3 questions to...

Vincent Beaumesnil (ACO Sports Manager)
"Avoid escalation, guarantee a level playing field and safety"
- Why have these modifications been made to the 2010 regulations?
"Regulations must evolve from one year to the next to adapt to the context. When you publish them, entrants interpret them, work on them, find solutions and performances increase just at the moment when we have to prevent performance escalation to guarantee a level playing field and safety".
- Do you work in close collaboration with the manufacturers?
"The ACO has gathered a great deal of data, as we have at our disposal a multitude of sensors and time sheets. But we have always worked in close collaboration with the manufacturers.
They supply us with their own data which we analyse taking into account performances, advantages and disadvantages of different types of engines (GT1 engines in a prototype, diesel, traditional petrol power units). After that, our role is to define a fair set of regulations to give each configuration the opportunity to race".
- Will the engine equivalences close the gap in performance between diesel and petrol-engines prototypes?
"We'll see the real effect out on the track, but in any case it's the aim of this adjustment, which demanded a lot of hard work. As you know, our races include several different categories in which the technologies are also different. With the arrival of new cars, we have to do things so that all these technologies can co-habit properly, and then make the little adjustments that guarantee technical equality".

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