The Audi R15 TDI
AUDI AG is the world’s first automobile manufacturer to develop a "second” generation diesel racing sports car. Audi further improved the R15 TDI diesel race car for the 2010 season with the primary objective of securing victory at Le Mans.
"As far as Audi is concerned, the LMP1 is better than Formula 1 vehicles because this motorsport category involves technologies and developments that are relevant to series production,” explains Head of Audi Motorsport Dr. Wolfgang Ullrich. "The most important thing at Le Mans is efficiency. That’s precisely what is in greatest demand in production vehicles these days, and this is also one of Audi’s main strengths.”  
 
Efficiency – especially in relation to aerodynamics – was therefore a key focal point when the R15 TDI was being further developed. "This year’s Le Mans regulations prescribe smaller air restrictors and lower manifold pressure,” says Audi Sport’s Head of Technology, Dr. Martin Mühlmeier. "As the regulations resulted in reduced engine performance, we endeavored to make the aerodynamics even more efficient and improve the drag coefficient and downforce values. 
 
The entire shape of the R15 TDI bodywork has been reworked with maximum efficiency in mind, as has the modifi ed cooling and tank system. The V10 TDI engine has been optimized to cater for the smaller air restrictors and he reduced manifold pressure. The two air intakes have been reduced in size by just under two percent, from 37.9 to 37.5 millimeters. The manifold pressure, which is a key feature of turbo engines, had to be changed from 2.75 to 2.59 bar, which is a sizable reduction of 5.8 percent. "We aimed to keep the loss of power to a bare minimum, in spite of the curtailments introduced by the new regulations,” explains Audi Sport’s Head of Eingine Development, Ulrich Baretzky. "And we achieved this with a lot of work on details.” The 5.5-liter engine still generates more than 440 kW of power and it goes without saying that two diesel particulate fi lters clean the exhaust fumes of the Audi R15 TDI. The torque, which is still as big as ever, is passed on to the rear wheels by a pneumatically operated five-speed gearbox. 
 
"There were about 20 important points on our specifi cation sheet for the ‘R15 plus’ after Le Mans 2009,” says Dr. Martin Mühlmeier. "Most of them concerned issues of efficiency and reliability, but there were also details such as a request from the drivers for better night-time illumination of the racetracks. And we met this request with a new headlamp concept.”  
 
The new generation of the Audi R15 TDI is also equipped with a highly efficient electrical system. A lithium-ion battery and LED headlamps deliver an excellent light yield without adding excessive weight to the vehicle.  
 
The 2010 prototype of the Audi R15 TDI was fi rst put through its paces at the Audi proving ground in Neustadt at the beginning of March, before being fl own out to the USA to undergo testing, especially in relation to its aerodynamics. There then followed a fi ve-day endurance test at Sebring, in which the vehicle completed approximately 5,500 kilometers without any noteworthy technical problems. 
 
 
TECHNICAL DATA 
 
Vehicle type: Le Mans Prototype (LMP1)  
 
Chassis: composite-fiber design from carbon-fiber with aluminum honeycomb, complies with the strict FIA crash and safety standards  
 
Engine: 90° V10 engine, 4 valves per cylinder, DOHC, 2 Garrett turbochargers, 2 x 37.5 mm, engine air-intake restrictors, maximum turbo pressure of 2.59 bar absolute, diesel direct injection TDI, 2 Dow Automotive diesel particle filters, dry sump  
 
Electrics/electronics: lithium ion battery/Bosch MS 14  
 
Cubic capacity: 5,500 ccm  
 
Power: over 440 kW  
 
Torque: over 1,050 Nm  
 
Transmission/powertrain: Transmission rear wheel drive, traction control (ASR)  
 
Clutch: carbon fiber clutch  
 
Gearbox: sequential, pneumatically operated 5-gear sport gearbox, partner X-trac  
 
Differential: mechanical locking differential  
 
Driveshafts: constant-velocity tripod plunge-joint driveshafts  
 
Steering rack and pinion: electric power steering  
 
Suspension: independent front and rear double wishbone suspension, pushrod system with torsion bars and adjustable dampers  
 
Brakes: hydraulic dual-circuit braking system, monobloc light alloy brake calipers, front and rear ventilated carbon-fiber brake discs, driver adjustable infinitely variable brake-balance 
 
Wheels: O.Z. magnesium forged wheels, front: 13.5 x 18 inch, rear: 14.5 x 18 inch  
 
Tires: Michelin Radial, front: 33/68-18, rear: 37/71-18  
 
Dimensions/weight: Length 4,650 mm, Width 2,000 mm,  
Heigth 1,030 mm, Starting weight 930 kg, Fuell cell capacity 81 l  
 
 

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