Audi R8 V12 TDI

16Jan08

The V12 TDI powered matt silver Audi R8 concept represents a revolution in the high-performance class. The 6 liters V12 generates 500 hp and a peak torque figure of 1,000 Nm (737.56 lb-ft) at only 1,750 rpm. Sprints from 0 to 62 mph takes just 4.2 seconds, top speed is well over 185 mph.The V12 TDI was derived from Audi’s two-time Le Mans winner, the R10. The diesel engine in the R10 sports prototype won its very first endurance race at Sebring, when it was pitted against a field of gasoline-engined challengers. The V12 TDI race engine in the R10 produces over 650 hp from a displacement of 5.5 liters, giving it a potential top speed of over 200 mph. Unusual for a race engine, this powerful Audi diesel makes barely more than a whisper.The DrivetrainThe roadgoing version of the new V12 TDI is built at the Györ plant, in Hungary. Like other power units in this range, the distance between cylinder bore axes on the V12 TDI is 90 mm. Yet its included angle is 60 degrees. This means no free inertial forces or mass moments of inertia can occur with the V12. The results are refined in every respect.The bore and stroke are the same as in the 3.0 TDI. At only 684 mm (26.93 in.) long, this large diesel engine is very compact and just 166 mm (6.54 in.) longer than the V8 TDI. This compact length is key to accommodating the V12 in the midengined Audi R8.The V12 TDI crankcase is gray cast iron with vermicular graphite making it 40 percent more rigid and 100 percent more fatigue-resistant than gray cast iron. This enabled engineers to make the walls thinner, cutting weight by around 15 percent compared with conventional gray cast iron.Ultramodern Injection TechnologyAs is the case in the Audi V engines, the no-maintenance chain drive is mounted at the back of the engine, where it occupies little space. Its layout has changed on the new V12 TDI. The camshafts’ sprocket engages in an intermediate gear via which two Simplex chains drive the camshafts. Two more chains drive the oil pump and the two high-pressure pumps actuate the common rail injection system.Two Bosch high-pressure pumps build up a pressure of up to 2,000 bar in the common rail injection system. Piezo injectors with eight-hole nozzles release the mixture in the combustion chamber. Besides the main injection there is pilot injections to tone down the acoustic harshness. Retarded post injections increase the exhaust temperature, promoting regeneration of the two particulate filters. This refined process increases power, cuts consumption and reduces pollutant emissions. Two turbochargers are located on the outside, each of them supply one bank of cylinders. Thanks to their variable turbine geometry, the chargers respond slickly even at low engine speeds.The two turbochargers generate up to 2.6 bar of boost pressure, play a crucial role in producing the huge torque of 1,000 Nm (737.56 lb-ft) that the V12 TDI maintains from 1,750 rpm to 3,000 rpm. In developing 500 hp, the diesel achieves a specific output of 84.3 hp per liter displacement.Two large intercoolers reduce the temperature of the compressed air. The V12 has a twin-pipe exhaust system with two particulate filters. The intake system is similar in structure with one air cleaner per cylinder bank, with an airflow meter behind it. Two control units, sharing the workload in a master/slave principle, manage events in the engine.The Audi R8 V12 TDI concept already fulfills the Euro 6 emissions standard that is likely to take effect in 2014 and calls for sharply reduced nitrogen oxides. By also designing in ultra-precise fuel metering by the common rail system, Audi’s engineers have made full use of current clean diesel technology.The heart of the system is a special catalytic converter downstream of the oxidizing catalyst and the particulate filter. The second component in the system is an additional tank containing an aqueous urea solution. Small quantities of the solution, known as “AdBlue,” are injected into the exhaust system. The hot exhaust gases break the solution down to form ammonia that splits the nitric oxides into nitrogen and water. The system remains effective for the entire service life of the vehicle.The very compact transmission in the R8 V12 TDI has six manually operated gears. Together with the smalldiameter double-plate clutch, this means it can be installed low down. The manual transmission has very short shift travel and utterly precise guiding of the shifter into the polished aluminum open gear lever gate.Such a high-performance Audi also has quattro permanent all-wheel drive. In the case of this mid-engine sports car, power is distributed variably between the front and rear wheels from a starting ratio of 40:60 to optimize the handling.The DesignThe R8 V12 TDI concept with matt “Grace Silver” bodywork looks even wider and more resolute than the core model. It shows its potential through its muscular proportions, accentuated wheel arches and even larger air apertures. The R8 sideblades are much wider in the bottom third visually accentuating the engine’s position as well as acting as an enlarged air deflector.The continuous aluminum spoiler lip that connects the front and rear diffusers with side air baffles below the enlarged sills also pays tribute to this version’s highly developed dynamic talents.The selective but precise use of lines is another typical Audi characteristic, as is the curved arc of the roof. One new aspect is the glass roof of the passenger compartment with two large transparent sections. The NACA duct in the middle of the roof is a functional detail that is normally reserved for racing cars. Its ingenious shape accelerates the air drawn in here for the two cylinder banks of the V12 TDI engine.The V12 TDI is displayed as the beating heart of this sports car, like a work of art inside a large showcase. Its look, underscored by the air deflectors located beneath the restyled rear glass lid, differs clearly from its production counterpart. After dark white LED’s illuminate the engine compartment that can be fully lined in genuine carbon fiber. The continuous line running from the front apron across the wheel arches and flanks to the tail end, then back down the other side, is one of the latest design hallmarks of the Audi brand. This “loop” naturally encompasses the air apertures, the headlights and the taillights.Unmistakable Face by Day and NightThe passion expressed through the design of the lights is another typical Audi trait. Nor is anyone likely to overlook this Audi sports car from behind: the LED taillights have a three-dimensional look that can’t be missed. The highlight is the all-LED headlights of the concept vehicle. With their lenses and reflectors, not only do these innovative light sources have a ground-breaking appearance, they also have an enormous functional advantage: LED light, with its color temperature of 6,000 Kelvin, resembles daylight much more closely than xenon or even halogen light. Better light means the driver will have much less fatigue when driving at night.

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