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24 HOUR RACE TECHNOLOGY VOLUME 5 2011
DOSSIER : AUDI LM P1 The #2 ran day, night and the second day without problems (All photos: Anne Proffit) Dr Wolfgang Ullrich, Head of Audi Motorsport A SPECIAL REPORT
BATTLE OF THE COUPES Audi beats Peugeot at its own game
competition Closed
THE PROTOTYPE CHASSIS Under the skin of today’s Le Mans cars
POWER AROUND THE CLOCK Endurance race engine design secrets
Anne Proffit reports on how Audi’s preparations for this year’s LM P1 race paid off on the podium
T USA $50, UK £20, EUROPE E35
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he 2011 R18 TDI coupe was the third new Le Mans car from Audi in the past three years. Its appearance was triggered by changes in the regulations that downsized the largest permitted turbo diesel engine from 5.5 to 3.7 litre
displacement. Audi opted to move from a twin turbo V10 to a single turbo V6, with the turbocharger located within the vee in the interest of its feed from an overhead air intake and in the interest of overall car packaging. A forced reduction of fuel tank capacity also assisted packaging, opening up even more scope for the aerodynamicists, who found that a coupe body rather than Audi’s traditional open cockpit approach maximised the potential they had to play with. Dr Wolfgang Ullrich, head of Audi’s motorsport department, had long been a fan of the open car, starting with the first R8R of 1999. After seeing the results of wind tunnel tests with a closed roof placed on the outgoing R15 TDI, even he was convinced it was time to change. New refuelling rules for this year took some of the emphasis away from quick driver changes, a hallmark of the previous, open Audi Prototypes.
Even with the obvious additional mass represented by a coupe body,
aided by a significantly lighter engine Audi reduced the overall weight of the new racecar, its base weight coming in at 850 kg, a figure that permits the careful allocation of 50 kg ballast about the car to meet the mandated 900 kg minimum. Audi would prefer to see 850 kg adopted by the Automobile Club de l’Ouest (ACO) as the minimum weight for all non-hybrid LM P1 prototypes, a premise that had not been met with approval by the ACO at the time of writing. Everywhere at the Le Mans circuit, there were advertisements for
Audi’s ultra-lightweight principles, the manufacturer’s trend in road- going machines, all on diets aimed at increasing efficiency without sacrificing power and handling characteristics. Audi’s Le Mans cars have, of course, always been as light as feasible within the prevailing conditions and the 2011 car was no exception. A trio of Audi R18 TDI coupes came to Le Mans following third- and fifth-place positions on the car’s debut at the Spa-Francorchamps road course. Third and fifth places were not exactly what Dr Ullrich
had been looking for; his team had been beaten by the new 3.7 litre V8 Peugeot 908 turbodiesel at Spa. Prior to that the Audi team had contested the season-opening 12 Hours of Sebring Intercontinental Le Mans Cup (ILMC) race with two of its holdover open-cockpit R15 Plus machines.
Although the new R18 TDI racecar wasn’t ready for Sebring it had been put through its testing paces less than 100 miles further down the Florida coast at Homestead-Miami Speedway. Testing moved to the Sebring circuit for four days following the 12-hour race, with all factory drivers nominated for Le Mans on-hand. “We did a lot of testing on track and we’ve been on special
racetracks where you can do good aerodynamic work,” Dr Ullrich reported. “Sebring for sure isn’t the place to do that but we tested there after the race. We also tested on an oval in Germany and on an oval in the United States [both of which he declined to identify]. Those ovals are where we did our initial aero testing.”
Wide angle six The first track test for the R18 TDI took place in November 2010, a full five months after arch-rival Peugeot Sport had begun the track testing of its V8-powered 908 turbo diesel. Not only would Audi be behind Peugeot in critical on-track test time leading up to the 2011 six-race ILMC series and the headline Le Mans 24-hour race, it had also decided to tackle the challenge of a V6 engine with a wide 120º bank angle and a single Garrett turbocharger providing 3.0 bar absolute plenum pressure. The rules also force it to breathe through a single 47.5 mm air restrictor. Ulrich Baretsky, head of engine development at Audi, said his engine team made this configuration choice, which lowers the centre of gravity compared to a 90-degree bank angle but sets the weight of the turbocharger high, to enhance airflow to the turbo and to enhance car packaging. The air intake is on the roof of the car, giving a direct line to the turbocharger; the single exhaust outlet pipe exits through the rear deck of the racecar.
“We did a lot of testing on track, and we’ve been on special tracks where you can do good aerodynamic work”
All three Audi R18 TDI coupes lined up for scrutineering in downtown Le Mans
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24HRTv5 contents
• Dossier: AuDi LM P1 Anne Proffit reports on how Audi’s preparations for this year’s LM P1 race paid off on the podium
• insigHt: Le MAns engines What are the guiding factors in designing a petrol race engine for LM P1 competition? Oliver Allan reports
• Focus: trAnsMissions Lawrence Butcher examines how manufacturers have made huge leaps in improving the durability of transmission systems for Le Mans racing
• Dossier: HoPe rAcing
LM P1 HYBriD What does it take to prove that a flywheel- based hybrid can compete at LM P1 level? Anne Proffit finds out
www.highpowermedia.com
Focus: PrototYPe cHAssis What are the ingredients needed to create a top-flight sportscar chassis in the 21st century? Lawrence Butcher finds out
• Dossier: roBertson
rAcing ForD gt Anne Proffit explains how a family-owned team won a podium place at Le Mans with the venerable Ford GT
• Le MAns 2011 A review of this year’s Le Mans engines, results plus our directory of suppliers
• Ps: AuDi AnD LM-gtP Recalling the late 1990s, and the evolution of the Audi R8C
RACE ENGINE TECHNOLOGY SPECIAL REPORT
24 HOUR RACE TECHNOLOGY 2011
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