Audi and Peugeot diesel sportscars set to battle in Le Mans 24 Hour
By Loz Blain
June 14, 2007
June 15, 2007 Since the invention of the automobile, winning on Sunday has meant selling lots of cars on Monday and beyond and this weekend’s running of the fabled Le Mans 24 hour race looks set to influence a lot of sales over the coming decade. It all started when Audi began strategising for a nationwide Diesel road car offensive in the USA and the increasingly popular American Le Mans Series was seen as the perfect platform. Watch the race progress here, and read on for the background on this exciting encounter.
Audi had a great starting point in building the new diesel-engined race car. Its R8 race car introduced in 2000 was the most successful sports car in history, winning five of six Le Mans 24 hour races it entered, plus 50 victories in the American Le Mans Series plus numerous other endurance race wins.
The R10 TDI uses a purpose-built, all-aluminium, 5.5-litre, twelve-cylinder bi-turbo TDI power unit producing over 650 bhp - significantly more than the 550 bhp of its R8 predecessor. Most significantly, it produces more than 1100 Newton metres of torque, a figure that required the race department to build a new dynamometer, not to mention a five-speed gearbox capable of handling this brutal output. The usable power band lies between 3000 and 5000 rpm, an unusually low rev range for a racing engine and one which enables drivers to change gear far less often than in the R8 because of the TDI engine’s meaty torque curve.
The resultant car was the first of a new breed of race machinery with the advantages of TDI technology - superior efficiency, lower fuel consumption, enormous torque and exceptional power . Unlike the roadgoing diesels we all know, the R10 TDI can only be recognised acoustically as a diesel-powered sportscar during the warming-up process or in pit lane.
The R10 is equipped with a pair of diesel particle filters for the 24 Hours of Le Mans, so the customary flashes of flame from the exhaust, which are created by unburned petrol in spark-ignition engines, are missing. One of the diesel engine’s biggest advantages is the low fuel consumption, especially at part-throttle and overrun. However, when compared to more classic circuits which demand a higher ratio of part throttle, the lower specific consumption will hardly be noticeable at Le Mans because the quota of full-throttle is almost 75 percent.
The R10 TDI posted phenomenal results in its 2006 debut season of racing, going undefeated until April 2007 in the American Le Mans Series competition and winning Le Mans in a canter. It would have been reasonable to expect that Audi would rule the roost with the R10 for several years with such a head start on the competition.
Announced in June 2005, Peugeot’s Le Mans programme did not really get underway until the last WRC competition was over in November 2005. After that, the Peugeot Sport team reorganised to produce a mock-up of its own V12 HDi FAP engine in June 2006, followed by a mock-up of the 908 HDi FAP at the Paris Motor Show in September 2006, unveiling the 908 near Paris in January of this year.
Until the end of 2005, Peugeot Sport concentrated on identifying its main technical options and fine-tuning the technical team for the new programme. The pace then hotted up to cope with the very short lead-times. In early March 2006, the concept of a closed car was settled on, with the single-cylinder engine simultaneously being put through its paces on the test bench. In April, the mock-up of the 908 underwent the first wind-tunnel test.
The design of the shell was finalised in July, with assembly of the first V12 HDi FAP engine in September. This had its first test bench start-up the day after the 908 HDi FAP was presented at the Paris Motor Show. As soon as the shell arrived in mid-December, the assembly of the first car began for a burn-in on 31 December 2006.
Between the test periods, mainly designed to iron out any problems and develop the car, two other chassis were built, taking the number of 908 HDi FAP to three. Two of these are being used in races, and the third is used for development work.
The all-aluminium 5.5 litre V12 HDi FAP engine is even more brutal than the Audi, producing 700 bhp and 1200 Nm of torque. The choice of a twelve cylinder engine helps keep the cylinder bore diameter very close to that of a production series engine to leverage Peugeot's extensive knowledge of diesel combustion and ensure the engine has a reasonable piston stroke.
So far in 2007, the Peugeot 908 HDi FAP has had two starts for two very emphatic wins. On April 15, Nicolas Minassian and Marc Gené took a 908 HDi FAP into the winners circle at Monza in its first appearance at the Le Mans series, with a second Peugeot crew of Stephane Sarrazin and Pedro Lamy taking third. Three weeks later, Sarrazin and Lamy turned the tables with a flag-to-flag win in Valencia
Now the Audi and the Peugeot are facing each other for the first time in the biggest Le Mans race of them all – the real deal over 24 hours at Le Mans and the 908 HDi FAP has leapt out of the gates at a blistering pace and set a provisional pole for the upcoming 24 Heures Du Mans race, a half a second ahead of the Audi. So this year's Le Mans is shaping up to be a battle of the latest generation high-torque diesels - and a test of whether the lightning-quick Peugeot has the reliability to take on the rock-solid Audi over 24 hours of hard endurance racing.
Le Mans week action kicked off Wednesday evening with the first official practice session which saw Team Peugeot Total claim the fastest and third fastest times in the dying seconds. The evening’s run was interrupted by two red flag incidents, and was also upset by a brief but heavy thunderstorm that dumped rain over much over the French circuit. Stéphane Sarrazin (N°8 Peugeot 908 HDi FAP) and Nicolas Minassian (N°7) profited from drying conditions late in the session, however, to post their quickest times in a particularly thrilling finale. Practice resumed last night but rain soaked the track for the final qualifying session and the times from Wednesday have decided the grid positions – they’re not nearly as important as with shorter races, but provide an insight into the Peugeot’s potential.
The two four-hour test sessions organised on the Wednesday and Thursday evenings prior to the weekend’s celebrated 24-hour classic are, along with the preliminary test day organised earlier in the month, the only chance teams get to put the finishing touches to their race preparations round the full 13.629km track. The job list traditionally involves fine-tuning the set-ups of the cars in race-trim, completing final systems and fuel consumption checks, and ensuring all drivers cover the mandatory minimum number of night-time laps (three). Plus, if conditions and time allow, attempting to secure the best possible position on the grid for the start of Saturday’s race (3pm).
And that is exactly what Team Peugeot Total succeeded in doing on Wednesday evening in an exciting final flurry of top times that saw Stéphane Sarrazin (N°8 Peugeot 908 HDi FAP) post the quickest lap of the day in the dying seconds of the session. In an all out attempt on his final lap, during which he admitted to being very close to the limit, the Frenchman succeeded in toppling his rivals from top spot with an emphatic 3m 26.344s, while team-mate Nicolas Minassian narrowly failed in his bid to join his team-mate on the front row of the provisional grid.
Minassian and Sarrazin monopolised the driving of their respective cars during the first half of the session before the storm broke. After a short initial run, the two Frenchmen pitted (to fine-tune the set-up in the case of the N°7 car and to make a precautionary rear wheel-bearing change in the case of car N°8) before going back out on fresh rubber. However, despite laps of 3m 29.836s (N°7) and 3m 29.635s (N°8) - which put them 4th and 2nd respectively on the timesheets - both drivers suggested they could have done better had they not been caught in traffic, while Minassian’s second flying lap was thwarted when the red flag was shown for the first time.
With lingering damp conditions forcing the team to switch to wet weather tyres, much of the second half of the session was essentially given over to ensuring that Jacques Villeneuve, Marc Gene, Pedro Lamy and Sébastien Bourdais all completed their three obligatory night-time laps. Then, as the track began to dry, Sarrazin and Minassian threw all their strength into their bid to secure the best possible place on the grid.