2008 Audi R8 V12 TDI #2
Ultramodern Injection Technology
As 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.
The two new dual-piston high-pressure pumps form part of the common rail injection system supplied by specialty manufacturer Bosch. The two pumps build up a pressure of up to 2,000 bar in the rails. The piezo injectors with eight-hole nozzles have also been fundamentally revised.
The high pressure distributes the mixture optimally throughout the combustion chamber. The result is that the ignition process is faster, more homogeneous and more acoustically refined. The more efficient combustion process also increases power output, cuts consumption and reduces pollutant emissions.
The current generation of so-called inline injectors makes effective use of the piezo effect: piezo crystals expand in a fraction of a millisecond when an electrical voltage is applied. The number of injection processes per operating cycle can be varied across a wide range thanks to piezo technology – reaching as many as five fuel injection operations in the case of the V12 TDI.
As well as the main injection, pilot and post injections are possible. Pilot injections tone down the acoustic harshness of the combustion process. Retarded post injections are designed specifically to increase the temperature of the exhaust gas, promoting regeneration of the two standard particulate filters.
The two turbochargers are located on the outside of the engine's V, each of them supplying one bank of cylinders. Thanks to their variable turbine geometry, the full flow of exhaust gas always passes through the turbine, so the chargers respond slickly – even at low engine speeds – and operate very efficiently.
The two turbochargers, which 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 368 kW (500 hp), the diesel achieves a specific output of 62.0 kW (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 dynamic character of a sports car depends not just on its performance and torque; the transmission ratios have to be right too. In keeping with the character of a high-performance sports car with unbeatable torque potential, the transmission in the R8 V12 TDI has six manually operated gears.
The manual transmission is very compact in design. Together with the small-diameter 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 open gear lever gate. It is made from polished aluminum, has an agreeable feel and exquisite sports car looks.
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 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 rhombus-pattern cover on the air inlets and outlets is the hallmark of Audi's sporty top models and a familiar feature of the current RS generation.
Typical of the side view of the R8 is the sideblade. Much wider in the bottom third, it visually accentuates 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.
And yet the R8 is unmistakable for its powerful, elegant basic proportions. The selective but always 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. These, together with the glazed engine compartment behind, create a radically new formal element. The unmistakable 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. The engine can even be seen after dark, when white light-emitting diodes illuminate the engine compartment – as on the production R8 version. This "showroom" can additionally be fully lined in genuine carbon fiber, for a particularly exclusive look.
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 Night
The passion expressed through the elaborate 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.
But the absolute highlight is the all-LED headlights of the study 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.
"Horsepower sells motor cars, but torque wins motor races."