When Audi joined the endurance racing scene in 1999 with the R8R and R8C, the company had very little experience. Valuable lessons were learned that first year and put to good use when designing the R8 for 2000. Dozens of victories later, including five at Le Mans, the R8 was left obsolete by the latest rule changes. Almost as impressive as the never-ending list of wins was the fact that in six years of racing the V8 engines never missed a beat. Between 2003 and 2005, fielding the cars was left to private teams, but with plenty of backdoor support from the factory. In those years, the competition had gradually caught up and passed the Audi for outright speed, but thanks to the car's superior fuel consumption and reliability the various teams kept racking up victories on both sides of the Atlantic.
Although having little more to prove, Audi set out to conceive a replacement for the aging R8 in complete secrecy halfway through 2003. Instead of trying to carry as much over from the proven machine, the German manufacturer decided to start with a clean sheet and took it upon themselves to finally remove the diesel powerplant's bad reputation as a performance engine. In Europe, the latest generation diesel engines are already very popular with the well known mileage advantage now matched with high horsepower and low noise figures. In one of Audi's most important markets, North America, people have yet to accept the fuel as a viable alternative to petrol. The company's marketing department must have figured this could be changed if an 'oil-burner' would start to win the world's most prestigious endurance races.
There had been attempts in the past to race a diesel powered sportscar, but these were usually poorly funded and failed miserably. If anything, these efforts showed that it would not be as easy as installing a diesel engine in a conventional chassis. Exploiting the regulations to the fullest a displacement of 5.5 litres was chosen for the new engine. High pressures in the combustion chambers and the common rail Fuel Injection system were a concern, so to get them as low as possible the designers opted for a V12 instead of a production engine derived V10 or V8. To cope with these inevitable high pressures, diesel engines are usually constructed from cast-iron, making them considerably heavier than their petrol counterparts. This was another reason for the designers to create the engine from scratch. Using some smart, but yet undisclosed design tricks, the boys at Audi managed to construct the twin Turbocharged, direct injection V12 completely from aluminium.
Just as with the R8, the chassis design for the new R10 was completed in-house, but construction was outsourced to Italian experts Dallara. In the same way, many other parts were built by third party specialists to Audi's specifications. The new regulations, and the larger dimensions and weight of the V12 engine resulted in different proportions compared to the R8. Most noticeable is the considerably longer wheelbase. The weight balance also shifted forward, which was addressed by fitting wider front tires. The monocoque type chassis specified is relatively conventional in design and construction, but the front and rear suspension is again somewhat unusual. Up front the upper wishbones are exposed to the airflow, clothed in carbon fibre cowlings, in similar fashion as the final version of their sister company's Bentley Speed 8. Pushrod actuated torsion bars are combined front and rear by a third spring to control the dive and squat. New for sportscar racing are brakes that feature plates on both sides to increase cooling and aerodynamic efficiency. For the spectators this means a lack of the popular glowing discs. Finally there is the XTrac built semi-automatic gearbox, which only has five gears; sufficient for the low revving engine and strong enough for the high torque figures.
Ending months, maybe years of speculation, Audi officially unveiled the R10 in December of 2005 at the Trocadero square in Paris. Together with the revolutionary car, a carefully planned schedule for 2006 was presented with the Sebring 12 Hours and the 24 Hours of Le Mans as the most important appointments. As a warning to the competition and another clue for the skeptics, Audi released the performance figures for the V12 oil burner; 650 bhp and 1100 Nm available from around 3000 rpm. Prior to the launch, the car was shaken down briefly by long time factory driver Frank Biela, but the real testing was yet to begin with just three months until the first appointment. It proved to be more than sufficient to get the R10 up to speed at Sebring as the two cars entered qualified first and second. With Audi's impeccable reliability record, many believed it would be an easy, and of course historic victory for the diesel V12. A last minute repair forced one of the cars to start from the pits, but within the first hour the two silver Audis were easing away from the field. The leading car suffered from telemetry problems and the team was unaware that dirt clogged the radiator causing the engine to run hot. After two hours the problem was spotted and the car was retired to prevent the engine from blowing. After being thoroughly cleaned, the other R10 continued to lap the concrete track well ahead of the competition. The historic first diesel win was scored at their first opportunity.
In preparation for the 24 Hours of Le Mans, Audi continued the intensive testing schedule in relative secrecy, while the competition tried their machines in the Le Mans Series in Europe and the ALMS in North America. So up until the official test day, less than two weeks before the race, it was uncertain how the new Audi would fare against the higher rated European competition. It was also the first opportunity for us to see the racer in action and it impressed us greatly by being eerily silent and immediately on pace. Both cars were in the top four of all day and finished the eight hour session in second and fourth, beaten only by the two Pescarolos. In the last qualifying session for the race it became obvious that the pace during the test day was deceiving as the two Audis took a convincing one-two.
All seemed well for the race until the #8 was pulled off the grid for last minute gearbox repairs. Fortunately it was ready in time for the five o'clock start, which saw the two Audis take off in the distance. The #7 car hit trouble overnight, but there was no stopping the repaired #8 car, which cruised to a ground-breaking first diesel win at Le Mans. The two cars were then shipped to the United States where they competed in and won all the remaining rounds of the ALMS. The R10's domination was so big that the organizers allowed the other LMP1 cars to run considerably lighter, but the rock-solid reliability and pace were sufficient to complete the 2006 season unbeaten.
Actually Henri Pescarolo quoted several times that the real power of the R10 TDi engine is somewhere around 700 hp - and that was for 2006! The 2007 car, and the 2008, might get even stronger. The top speed difference between the R10 2006 and the R10 2007 at Le Mans was 329 km/h vs. 339 km/h. It's also true that the Tetre Rouge entrance to Hunaudieres was changed, but anyway... 339 km/h starts to sound again like the 1999 times :D I'm really curios about the R10's performance in 2008!
Great looking car, even if itsn't as good as the former R8 FSI was, the V12 diesle TDI, is too powerfull without creating any noise, for Le Mans 2006 it was very easy againt Pescarolo and the rest of the P1 field, but for 2007, Peugeot is coming with a close LMP1, the 908 HDI as well as Pescarolo with a brand new chassis. In ALMS it will run lonely in P1 class againt factory teams from Porsche and Acura, both in the smaller class.