Audi R10 TDI, the first diesel powered car to win the Le Mans

German carmaker Audi created history by winning the Le Mans 24-Hours race employing a diesel powered car

Audi re-wrote the motorsport history at the recent Le Mans 24-Hours race. The Audi R10 TDI became the first diesel-powered car to win the world's toughest race, kick starting a new age of technological development. The overall race, in front of a record 235,000 spectators, was won by the Audi trio led by German Frank Biela and partnered by fellow countryman Marco Werner and Italian Emmanuele Pirro.

What many failed to notice was the work that went into preparing the R10 TDI for the victory run. Tier supplier, Bosch, together with Audi developed the diesel-injection system for the successful Audi R10 TDI racing cars, supplying high-pressure pumps, injectors, and the engine control unit for the motor-racing common-rail system. On June 18, 2006, the two racing cars came in first and third. With this result, the two companies have notched up a further success for their motor-racing alliance: in past years, Audi won several races in Le Mans with the predecessor model, the R8, whose FSI direct injection system was also developed together with Bosch. "We are pleased that this year we were able to play our part in racing success with our innovative diesel injection equipment," says Dr. Ulrich Dohle, president of the Bosch Diesel Systems division. "In recent years, high performance and low consumption have already helped the diesel engine to success in series-produced models. Now, the diesel has also shown what it can do on the race track."

As development partner, Bosch supplies the specially adjusted high-pressure pumps and piezo-inline injectors for the common-rail injection system installed in the R10 TDI. Its engineers have also used the specific racing know-how of Audi Sport as the basis for developing the new electronic control unit for the car's 12-cylinder engine. The 5.5-litre, 12-cylinder engine is a TDI, twin-turbo, fuel saving and silent unit. It develops a maximum power above 650 hp and more than 1100 Nm torque, which exceeds previous Audi racing engines including the previous R8. Audi ventures in an uncharted territory of diesel engines building a V12 entirely of aluminium. The same way Audi proceeded with the TFSI technology, which triumphed at Le Mans before it was taken into production, the same is expected to happen with this V12.”

"With A8 4,2 TDI Quattro Audi is building already one of the most powerful diesel engine powered car in the world", explained Martin Winterkorn, president of the administration council of Audi. He is also known to have said at the R10 presentation at Paris on the eve of the race that "The Le Mans Project will allow our specialists to obtain more out of the TDI technology. At this time one out of two Audi cars sold is powered by a diesel engine. We expect a growth in the diesel percentage in the future".

The V12 TDI engine was created at Audi Sport in the Sport and Special Engine Department which is located at the factory in Neckarsulm. "The direct link between Audi Sport and the AUDI AG Technical Development (TE) is one reason why we are so successful in motorsport”, explains Head of Audi Motorsport Dr. Wolfgang Ullrich. "We are able to resource completely the know-how and test rigs of our colleagues in the road car development. This made it possible for us to implement the advantages from Audi’s production technology into the first Audi TDI race engine at the 24 Hours of Le Mans, the world’s toughest car race – and all this in the shortest possible time frame.

At Audi, the transfer between motorsport and production technology also functions in the opposite direction. The Le Mans engine’s crankcase is manufactured from aluminium – a design that could well be seen in mass production in the future at Audi. The race engine’s fuel injection pressure lies well over the 1,600 bar that is currently achieved in production engines. The combustion pressures also reach values previously never before seen in any Audi engine. Dr. Wolfgang Ullrich is convinced that, “This engine will form the base from which the next generation of Audi TDI engines will do everything a little better than they do already today.” “For Audi, motorsport is more than a simple marketing instrument. The technology transfer between motorsport and production is very important to us. Last weekend’s Le Mans race is the latest proof.”

The V12 TDI engine has two particulate filters and is hard to recognise as a diesel engine because of its refinement. Audi engineers took the characteristics of the TDI street engines to a completely new level. The injection pressure exceeds 1600 bar. The power band is limited below 3000 and 5000 rpm, very low for a competition car. This way the R10 driver shifts gears much less often than in a R8, thanks to the generous torque response of a diesel engine. The huge torque of 1100 Nm created difficulties for the transmission of the R10 and even the newest technology of dynamometers from the Audi Sport garages had to be re-equipped to face this engine's torque.

Then, major changes to the chassis of the car were needed, claim industry sources, to handle the enormous torque of the V12. While the Audi R10 has a longer wheelbase than R8, the front tyres, which are extremely wide, are unique for a Le Mans racer, add sources. A series of new technologies in developing the mono-block carbon fibre body were employed even as the chassis, engine and transmission form a very rigid unit.

When developing the injection system of the V12, the greatest challenge was the variable control of the extremely high injection pressure. Bosch also supplies the telemetrics system that ensures an uninterrupted transmission of data from the vehicles to the pits during the race.

Bosch has pooled all its motor racing activities into one separate unit, "Bosch Motorsport." It is part of Bosch Engineering GmbH, the Bosch subsidiary that specializes in engineering services. Motor racing services at Bosch can look back on a long tradition: as early as 1903, Bosch engineering first helped racing drivers to victory.

Interesting, as it may sound, Bosch also partnered with French automaker, Peugeot, to create the Le Mans racer, the Peugeot 908. It is a 5.5-litre twelve-cylinder, common-rail, 100-degree vee, engine that delivers 700 bhp of power and more than 1200 Nm of torque.