DETROIT – Add another 500-hp super car to the growing list.
But this one, the Audi R8 V12 TDI concept bowing at the North American International Auto Show here, is diesel powered.
Audi AG says it is “writing a new chapter in diesel technology” with the R8 V12 TDI’s race-bred 5.9L V-12 engine, which already appeared in concept form at last fall’s Paris auto show lodged under the hood of Audi’s Q7 cross/utility vehicle.
The larger-displacement V-12 is derived from the 5.5L 650-hp diesel that powered the R10 racecar to wins at the 24-Hours of Le Mans in 2006 and 2007. However, the concept V-12 features a 60-degree angle between the cylinder banks, not the 90-degree offset of R10’s engine, though the distance between the banks remains 3.54 ins. (9.0 cm).
Bore measures 3.27 ins. (8.3 cm) and stroke stretches to 3.6 ins. (9.1 cm) to produce the 5.9L displacement, identical to Audi’s 3.0L TDI V-6. At 26.9-ins. (68.4 cm) long, it is only 6.54 ins. (16.6 cm) longer than the auto maker’s 4.2L TDI V-8.
Like the V-6 and V-8 TDI engines, the V-12 boasts a crankcase crafted from gray cast iron and vermicular graphite (also known as GJV-450). It is 40% more rigid and twice as fatigue resistant as one made solely of gray cast iron, Audi says. That extra strength allows for thinner walls, cutting crankcase weight 15% from that made with the more conventional material.
A no-maintenance chain drive employs two chains to regulate the camshafts and two more to trigger the oil pump and two high-pressure pumps that actuate the common-rail injection system. It is mounted at the back of the engine, conserving space.
Robert Bosch GmbH supplies the two new dual-piston high-pressure pumps that supply up to 29,000 psi (2,000 bar) of pressure to the fuel rails. Audi says the high pressure helps distribute fuel more evenly throughout in the combustion chamber, resulting in an ignition process that is faster, more homogeneous and quieter. It also boosts power and cuts fuel consumption and emissions, the auto maker says.
The engine’s twin turbochargers add up to 38 psi (2.6 bar) of boost pressure and help deliver a whopping 738 lb.-ft. (1,000 Nm) of torque and 84 hp/L.
Temperature is controlled via two large intercoolers. Two filters are incorporated along the twin-pipe exhaust system to trap particulates, and a special catalytic converter, downstream of the oxidizing catalyst and particulate filters, further cuts emissions. Also employed is Audi’s AdBlue urea-injection technology to break down oxides of nitrogen emissions before they leave the tailpipe.
Audi says the concept engine meets Euro 6 emissions standards likely to take effect in 2014.
The R8 V12 TDI is distinguished further by its matte-finish “Grace Silver” body Audi says was designed to give the car an “even wider and more resolute” appearance than the production model. A continuous aluminum spoiler lip connects the front and rear diffusers with side air baffles below the car’s enlarged sills, adding to the concept’s aggressive look.
Even more distinctive is the car’s twin-panel glass roof, bisected by a NACA duct, a feature typically limited to racecars. The engine compartment also has a transparent cover, distinguished from the production car’s by the air deflectors located beneath the glass lid. White light-emitting diodes provide light to the engine bay after dark.
Unlike the production model, the concept gets all-LED front headlamps. Inside the concept makes greater use of aluminum accents, particularly around the center console.
Aerodynamics are improved via a larger, rear spoiler that extends further at higher speeds, plus a fully clad diffuser underbody. Audi’s magnetic ride, which automatically adjusts suspension damping, is included on the concept. Carbon-fiber brakes, optional on the production R8, also are onboard the concept.