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The Audi R10 is a racing car prepared for sports car racing in the LMP1 class of the 24 Hours of Le Mans and other similar endurance races. The car was unveiled Tuesday, December 13 2005 at 12:00 CET, and went on to win both its maiden race at the 2006 12 Hours of Sebring and the 2006 24 Hours of Le Mans. It was the first diesel powered car to win either of those events. This is the most ambitious and the most expensive project ever undertaken by Audi Motorsport; the Audi R10 project costs Audi $15 Million a year.
Chassis
It supersedes the previous Audi R8, a proven model which won five times at Le Mans since 2000 while earning a reputation as one of the most successful racing cars of all time. In later years the ACO, who sets the rules for racing in the Le Mans 24 Hours, has reduced the restrictor size on the engine, and stipulated the R8 carry ballast, to make the races more competitive. In response to the new level of competition the development of a successor was necessary.
Though it bears a strong resemblance to the previous model, it is nevertheless a new design. The aerodynamic package is in compliance with the new regulations. A second rollover hoop is added and the wheelbase is lengthened to accept the new, longer V12 TDI engine. The design and aerodynamics were developed by Audi but the monocoque is built by Dallara and various suppliers, and then assembled at Ingolstadt.
Weight
At the beginning of the 2006 season, homologation rules for LMP cars were changed, for the LMP1 class, an increase in minimum weight from 900 kg to 925 kg was mandated. While officially this is to allow closed top prototypes to run with air-conditioning (as this would have added weight over open tops cars), some have speculated that this done at the behest of Audi to allow the R10 to be competitive.
The R10 itself, as it ran during the 2006 12 Hours of Sebring was overweight at 935 kg, meaning that the engineers did not have the ability to play around with the weight ballasts (which would have been used to bring the car up to minimum weight if it were lighter than 925kg) to affect handling and balance.
Engine
The main novelty of the R10 is its engine: a TDI turbodiesel engine, running on Shell V-Power Diesel. It is a 5.5 L (335.6 ci) all-aluminium bi-turbo 90° V12, with common rail direct injection of more than 1600 bar (23,206 psi). Its output should be 485 kW (650 hp) (regulated) and 1100 N·m (811 ft·lbf) of torque, and its usable power band is between 3000 and 5000 rpm. Its benefits are a broad range of usable power, high torque and economy.
Two Garrett TR3076R turbochargers limited by the regulations to 2.94 bar (42.64 psi) absolute breathe through two 39.9 mm intake air restrictors. It uses the latest Bosch Motronic (MS14) management, provided by Bosch Motorsport, 1600 bar piezo injectors, and makes a low noise for a race car. It can be difficult to hear the R10 on a track when other cars are present because of the much lower noise level.
The weight of this engine is a problem for Audi. The latest Audi TDI 3.0 L V6 (183 ci) weighs 220 kg (485 lb) and the 4.2 L V8 255 kg (256.2 ci, 562 lb) but their blocks are made of CGI iron. The V12 is rumoured to weigh upwards of 200 kg; Audi engineers admit that the weight per cylinder is the same as the precededing 3.6-litre FSI V8 of the Audi R8. The wheelbase has been increased over the R8 to 2980 mm to account for this. This is unfavorable against the 130 kg (287 lb) of a concurrent Judd V10, and even the 180 kg of the Ricardo turbodiesel prototype based on it.
The restrictor is larger than necessary, the car is rumoured to produce 700 hp in qualification, limited by the fuel combustion quality. This value couldn't be maintained in race because it could clog the particulate filter. The peak pressure in the cylinder is probably around about 200 bar, compared with 85 bar for an atmospheric petrol engine.
Diesels racing at Le Mans
Audi's decision to use a diesel engine emphasizes the commercial success of TDI (and its competitors) on Europe's roads. Diesels have been successfully used in other forms of racing as well, as their broad power band and fuel economy can prove advantageous, while in turn, the higher weight and lower rotational speed of the engine requiring new power transmissions are the disadvantages. The rules had to accommodate the need for a high capacity engine with a turbocharger and high boost, whether both possibilities are no longer allowed for gasoline engines, as these had developed over 1000 hp in several race series of the past.
It isn't, however, the first diesel to be raced at Le Mans. The first diesel-engined car to qualify and race at the 24 h race at Le Mans was a French entry in 1949, the first race held after the war. The car was the Delettrez Diesel entered by brothers Jean and Jacques Delettrez and was a 4395 cc 6-cylinder. It did not finish, running out of fuel about half way into the race.
Delettrez entered again in 1950, as did another diesel car, the MAP. Again, both cars did not finished due to engine problems, a cooling system leak in the case of the MAP. The MAP was interesting in that it was the first mid-engined car to race at Le Mans; the engine was located immediately behind the driver, and was a two-cylinder opposed piston two-stroke with rocking levers connected to a single crank, similar to the later Commer TS3 engine.
In 2004, a Lola equipped with a Caterpillar re-badged VW V10 TDI ran for a few hours before breaking its gearbox. Peugeot competed with its new diesel effort in 2007 in its 908 race car.
Results
2006
On 18 March 2006, the #2 Audi R10 won the 54th annual 12 Hours of Sebring after earning pole position by setting a qualifying record. The #1 car did not finish due to an overheating problem. On the day after the Sebring victory an R10 flipped over during testing while running through Turn One.
On 18 June 2006, the #8 Audi R10 placed first at the 2006 24 Hours of Le Mans, completing 380 laps, more than the R8 did, but less than the record set in 1971. The #7 Audi R10, which set fastest lap times in practice and race, came in third after suffering injector pump damage, completing 367 laps. At one point, the Joest team changed the #8 car's gearbox in under ten minutes, compared to the hour and a half the fifth-place Pescarolo-Judd spent in the garage for similar repairs, prompting the ACO to change rules for the next season.
On 30 September 2006, the #2 Audi R10 won the 9th annual Petit Le Mans endurance race in Road Atlanta, Georgia. The win was seventh in a row for Audi in Petit Le Mans, but first for the R10 model. The #1 car was not running at the finish due to late race collision with another car resulting in damaged front suspension. #1 car was still classified in seventh place overall.
2007
On 17 March 2007, the #2 Audi R10 won the 55th annual 12 Hours of Sebring. The #1 car finished 2nd in its class (LMP1) and 4th overall. The R10 remained undefeated in American Le Mans Series competition until April 14, 2007 at the Long Beach Grand Prix; where it finished seventh overall to the Porsche RS Spyders of Penske and Dyson Racing. The car still won the LMP1 class.
It is however, still undefeated at the 24 hours of Le Mans as the R10 successfully defended its 2006 victory. On June 17, 2007, the #1 R10 finished first overall, overcoming the loss of two of the three team cars and defeating a new challenge from the Peugeot 908 HDi FAP diesels. The #3 Audi was put out of the race by driver error, whereas the #2 car suffered a wheel failure at approximately 300km/h and collided with a barrier. Video pictures showed the car being dropped prematurely during a prior pitstop with the wheel in question not being properly attached, but Audi's official statement is that the incident was not the fault of the pitcrew, as the car had been on track for over 50 minutes since its tires were last changed. Audi intends to carry out full technical analysis of this incident.
According to ACO's official data, the Audi R10 TDi reached a top speed of 329 km/h on the Mulsanne Straight in the 2006 race. In 2007, while changing their pace in order to beat Peugeot, the Audi R10 TDi hit 339 km/h on the Mulsanne Straight, which was faster than any other car in the race. The R10 TDi also set the best lap of the race at 3:27.176. The car seems to have managed a top speed of 354 km/h in practice at Le Mans in 2007, which would be the absolute speed record of an LMP car at Le Mans (since LMP's only run from the introduction of the two Mulsanne chicanes on). At the car's official launch in Paris, 2006, the Audi R10 TDi was presented as capable of reaching a top speed in the region of 370 km/h.
References
- "Audi Competes with Diesel Sports Car at Le Mans" (Press release). Audi Communication Motorsport via AudiWorld.com. 2005-12-13.
- Bill Center (19 April 2007). "San Diegan isn't discouraged about not being able to gain on rich Audi team". San Diego Union-Tribune.
- Michael J. Fuller. "2006 Audi R10". Mulsanne's Corner.
- Mulsanne's Corner News, 12.12.05, Michael J. Fuller
- Mulsanne's Corner News, 3.25.06, Michael J. Fuller
- 2006 Audi R10, Michael J. Fuller, Mulsanne's Corner, 2006
- Racing Toward Relevance, Christopher A. Sawyer, Automotive Design & Production, May 2006
- Ricardo-Judd Diesel V10, Mulsanne's Corner, 2003
- John Judd interview (17th July 2007). "Compression or Spark?". Energy Efficient Motorsport.
{{cite web}}: Check date values in:|date=(help) - Audi’s new diesel-powered R10 dominates Le Mans, Gary Watkins, AutoWeek, 06/19/06
- 55th Annual Mobil 1 Twelve Hours of Sebring Final Race Results, IMSA, 03/17/07