Audi R8 V12 TDI in Detroit Motor Show
Audi is presenting a revolution in the top class at the Detroit Auto Show 2008 – the first 12-cylinder diesel engine in a high-performance roadgoing sports car. The V12 TDI with a displacement of six liters powers a concept car based on the Audi R8. This unit generates a huge 500 hp and 1,000 Newton-meters (737.56 lb-ft) of torque. Audi is writing a new chapter in diesel technology with this power unit. Equipped with the expertise that Audi has built up through its motor sport activities, the R8 V12 TDI in matt “Grace Silver” embodies superb road handling, pioneering technology and fascinating design.
The V12 TDI is closely related to the engine in the Audi R10, the two-time Le Mans winner – so it catapults the Audi R8 into supercar terrain concerning performance too. It sprints from zero to 100 km/h (62.14 mph) in just 4.2 seconds and its top speed is well over 300 km/h (186.41 mph). The peak torque, reached at only 1,750 rpm, paves the way for effortless acceleration that is unrivaled even at this level.
The new V12 TDI belongs to Audi’s family of V engines but has the ideal included angle for this engine type of 60 degrees between cylinder banks. Its highlights include the new chain drive layout that includes the two newly developed high-pressure pumps for the common rail injection system.
Its sound is as thrilling as you’d expect in a sports car of this caliber. For all the subtle smoothness that typifies this design principle, the twelve-cylinder unit is full-bodied and equipped with energetic overtones that make no secret of its performance potential.
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.
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.
