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Audi R8 V12 TDI concept The Drivetrain The roadgoing version of the new V12 TDI is built at the Györ plant, in Hungary. And the R8 V12 TDI still has a massive 500 hp on tap. In developing the six-liter engine, it was a clear priority to integrate it into the current family of Audi V engines, of which many thousands of versions with 6, 8 and 10 cylinders have already been built – both gasoline and TDI. Audi's engineers were in an ideal position to use their experience building the racing engine to develop the road version. Like the other power units in this range, the distance between cylinder bore axes on the V12 TDI is 90 mm (3.54 in.). Yet its included angle is 60 degrees, not 90 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 83.0 mm (3.27 in.) bore and 91.4 mm (3.60 in.) stroke produce a total displacement of 5,934 cc – just like 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 mid-engined Audi R8. The V12 TDI crankcase is made from gray cast iron with vermicular graphite – a high-tech material referred to as GJV-450 that is already used on the V6 and V8 TDI engines. GJV-450, made by a patented casting process, is about 40 percent more rigid and 100 percent more fatigue-resistant than gray cast iron. This enabled the developers to make its walls thinner, cutting its weight by around 15 percent compared with conventional gray cast iron. The two cylinder heads are each made from three main elements. These are a base section made from a high-strength aluminum alloy incorporating the intake and exhaust ports, an oil-bearing upper section, and a reinforcing ladder frame supporting the two camshafts. The valves are actuated by low-friction roller cam followers; the compression ratio is 16.0:1. Map-controlled swirl variation of the combustion air has been adopted from the V6 and V8 TDI engines. This produces permanently optimized swirl concerning both emissions and high performance. 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 Chassis The precision chassis of the Audi R8 V12 TDI concept remains supremely in control of the sporty performance, but is capable of assuring relaxed driving pleasure over long distances too. The sports car is spontaneous and agile at obeying steering movements, always demonstrating exceptionally good driving safety. The suspension, with double wishbones at both the front and rear, is optimized for a neutral self-steering response and maximum ease of control. The study car, too, has the innovative dampening technology known as Audi magnetic ride. This adapts the chassis characteristic to the profile of the road and the driver's style within milliseconds. Ceramic Brakes with Extreme Reserves A generously dimensioned brake system supplies the necessary braking force. It applies a total of 24 pistons to the four brake disks, combining excellent performance with minimal weight and high durability. The disks are made from carbon fiber reinforced ceramic, a material that has repeatedly proven its worth in the aviation and aerospace sectors. The basis is very hard, frictionally resistant silicon carbide, with its diamond-like crystalline structure. Embedded in it are high-strength carbon fibers that absorb the stresses occurring in the material. The intricate geometry of cooling ducts in the ventilated disks prevents extremely high temperatures. The ceramic brake disk ring is bolted by 10 spring-loaded elements to a stainless steel central element that acts as the connection with the wheel's hub. The ceramic brakes are identifiable at a glance by the special red, six-piston monobloc aluminum calipers and the fixed calipers at the rear. The advantages of the ceramic brakes include a further reduction in weight of around 20 kilograms (44.09 lbs.), which in this case improves the handling characteristics and comfort. The high abrasion resistance permits an operating life of up to 300,000 kilometers (186,411 miles). Their key strength, however, is their ability to withstand very high loads. Even on the racetrack, for example, the ceramic brakes always maintain their full reserve performance. The Design 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. The Genes of the Winner Thanks to their high performance and pulling power, all Audi TDI engines are ultra-dynamic sources of power. The brand has often enough demonstrated its sporty character in its production cars, especially the six- and eight-cylinder 3.0 TDI and 4.2 TDI. Audi has also been writing a new chapter in its success story on the racetrack since 2006. The diesel engine in the R10 sports prototype won its very first endurance race at Sebring, Florida, when it was pitted against an entire field of gasoline-engined challengers. But its most crucial victories were surely in 2006 and 2007 in the 24 Hours of Le Mans, when it simply outclassed the international elite. The V12 TDI race engine in the R10 produces over 650 hp from a displacement of 5.5 liters, giving it the potential for a top speed as high as 330 km/h (205.05 mph) depending on the gear ratios. Its power and sturdiness immediately impressed both fans and experts, who were impressed by its restrained noise level. Unusual for a race engine, this powerful Audi diesel makes barely more than a whisper. Long traditions of motor racing and production technology complement each other at Audi. The FSI engine of the R10's predecessor, the R8, captured five wins at Le Mans with a direct gasoline injection system. Audi is also looking to maximize the advantage by using the race-tested FSI principle in its production models. The latest examples of this are the V8 with high-revving concept in the RS 4 and the production version of the Audi R8. Diesel Milestones from Audi Audi has reached another milestone in diesel technology with the new V12 TDI. The brand with the four rings has been performing vital pioneering work in this area for the past three decades. The first TDI auto engine made its debut in 1989. The 2.5 liter five-cylinder power unit developed 88 kW (120 hp) and 261 Nm, catapulting diesel driving into an entirely new dimension. This was followed in 1994 by a development version generating 103 kW (140 hp). This engine was optionally available with all-wheel drive – the first TDI quattro model. A new four-cylinder diesel appeared at that time in the Audi 100 and Audi 80, the 1.9 TDI developing 66 kW (90 hp) that has now become legendary. At the end of 1995 the output of this four-cylinder unit rose to 85 kW (115 hp) with the advent of pump-injector fuel injection. Slightly more than one year later, at the start of 1997, the world's first 2.5 V6 TDI appeared. With four valves per cylinder, it achieved an output of 110 kW (150 hp), and its top speed of 220 km/h (136.70 mph) made the Audi A8 the fastest production diesel on the market. The first eight-cylinder TDI followed in 1999 – a V8 engine with a 3.3 liter capacity. The 3.0 TDI made its debut early in 2004 as the first V6 diesel with inline piezo injectors in the common rail system. The 4.2 liter TDI launched in the A8 in 2005 is currently at the vanguard of Audi's TDI range. One in three A8 buyers in Germany chose this V8 engine. The next logical step was to make the V8 TDI available in the Audi Q7 in summer 2007. With extremely clean, ultra-low emission technology, Audi is continuing its tradition of leadership in diesel engine technology. In 1989 it was the Ingolstadt brand that developed direct injection technology. Since then the diesel engine has become around 30 percent more efficient. The equipment, specifications and prices stated herein refer to the model line offered for sale in Germany. Subject to change without notice; errors and omissions excepted.
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