Audi RS 6 Avant: World’s Most Powerful Wagon

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January 21, 2008

Source: Audi AG

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Text: At-a-GlanceEngineDrivetrainChassisStylingInteriorFeaturesThe RS Models

Photo Gallery: Audi RS 6 Avant

Discussion Forum: Audi RS 6

With an output of 426 kW (580 bhp), torque of 650 Nm, acceleration from zero to 100 km/h in 4.6 seconds and an electronically governed top speed of 250 km/h (optional: 280 km/h), the new Audi RS 6 Avant raises the bar for performance dynamics to new heights in the business class. The tiptronic automatic transmission and quattro permanent all-wheel drive transfer all of the immense forces to the road, without any losses; and the performance of the chassis, too, is equally uncompromising with DRC Dynamic Ride Control and heavy-duty brakes. Like all RS models from Audi, the new RS 6 Avant adheres to a strict philosophy – to achieve the ultimate in sporty performance without sacrificing suitability for everyday driving.

Breathtaking power and fascinating dynamics – the Audi RS 6 Avant lends new meaning to the term high-performance. Its 426 kW (580 bhp) make it the most powerful model in the current Audi portfolio and the most powerful production vehicle ever to bear the four-ring emblem. Its high horsepower also places it well above any competitor in the upper business category – it is simply the most powerful production wagon in the world.

The engine in the RS 6 Avant, whose power output comes from a displacement of 4,991 cc, is based on the V10 powerplants installed in the Audi S6 and Audi S8, but nearly all of its details have been newly developed. With its combination of a ten-cylinder layout, FSI direct fuel injection, two turbochargers and the same kind of dry-sump lubrication used in motor racing, this engine is totally unlike anything the competition has to offer. In terms of its power-to-weight ratio, too, the RS 6 Avant can rival the sports car elite: Every horsepower has to propel just 3.5 kg.

The turbocharging system provides extremely high and consistent delivery of the torque across almost the engine’s entire rpm range. Its maximum torque is an awesome 650 Nm, available from 1,500 to 6,250 rpm, while maximum power output is produced between 6,250 rpm and the engine’s top speed of 6,700 rpm.

The biturbo V10 catapults the Audi RS 6 Avant to the level of a high-performance sports car. Accelerating from zero to 100 km/h takes just 4.6 seconds, and the sprint to the 200 km/h mark a mere 14.9 seconds. The speed then keeps on rising rapidly until 250 km/h, at which point the speed governor gently intervenes. Audi also offers a higher top speed of 280 km/h as an option.

The ten-cylinder engine makes for fascinating driving in every situation. It closely and tenaciously follows the action of the accelerator pedal, instantly responding to even the slightest movement with a burst of acceleration. Its dual-branch exhaust system with two oval tailpipes accompanies the acceleration with a full, rich sporty sound, which perfectly rounds out this car’s high-performance profile.

The V10 – the ideal sport engine

A turbocharged ten-cylinder powerplant is the ideal recipe for sporty, dynamic performance. It has fewer components, lighter moving masses and less internal friction than a similar twelve-cylinder engine; the result is higher efficiency. Moreover, it is lighter and more compact – with all ancillaries, the engine in the new Audi RS 6 Avant measures only 670 mm in length, 790 mm in width and 655 mm in height. The length of the bare engine is 560 mm.

The V10 is a member of the Audi family of V-engines, which are all designed with a 90-degree included angle between cylinder banks and center-to-center spacing of 90 millimeters between cylinders. The offset between the two banks is 18.5 mm. The cylinder bore is 84.5 mm, the stroke 89.0 mm.

The crankcase is manufactured of hyper-eutectic aluminum alloy by means of low-pressure die-casting. This high-tech material unites low weight with high strength. The cylinder barrels of the single-piece crankcase are honed to mechanically expose the hard silicon crystals. The complete engine weighs only 278 kilograms – an outstanding achievement in the five-liter class.

A so-called bedplate design – an intermediate frame – gives the crankcase extremely high torsional rigidity and improves its vibrational behavior. Its cast-in bearing bridges, made from gray cast iron, reduce thermal expansion of the aluminum crankcase and keep the crankshaft’s main bearing clearances to within tight tolerances. The crankcase design features cross-flow cooling and has no ventilation openings between the crank chambers (pneumatic spring engine). This serves to recover energy at engine speeds of 2,500 rpm and higher, thus enhancing both power and fuel efficiency. The high-strength con rods are made of forged steel and the pistons, which are equipped with newly developed ring packages, are aluminum alloy. The common-pin forged steel crankshaft provides both increased strength and lower weight.

Dry-sump lubrication – for the ultimate in sporty driving

To meet the utmost demands in driving dynamics, a dry-sump lubrication system, known for its proven effectiveness in motor racing, was implemented in developing the engine’s oil circulation system. It features an extremely elaborate external oil tank and oil pump module, operating with numerous different vacuum stages. This ensures that lubricant is supplied to all engine components and the two turbochargers under all conditions – even at the extreme lateral acceleration forces of over 1.2 g of which the RS 6 Avant is capable. As a result, the dry-sump lubrication system has sheer limitless reserves, even under racetrack conditions.

The hydraulic variable valve timing system continuously adjusts all four camshafts through a crankshaft angle range of 42 degrees to vary valve overlap in response to engine loads and speeds. This optimizes volumetric efficiency for more effective combustion.

The camshafts, the oil pump module and the ancillary components are driven by maintenance-free chains at the rear of the engine. The valves, which are actuated by roller cam followers with hydraulic tappets, have a diameter of 33.9 mm on the intake side and 28.0 mm for the exhaust valves. To withstand high thermal loads, the exhaust valves are sodium-filled for improved cooling.

The fine oil separator that is integrated into the cylinder head works in accordance with the “Multitwister” separation principle, which ensures that the oil is returned directly to the cylinder head.

The V10 in the new Audi RS 6 Avant operates by means of FSI direct fuel injection. A common rail injection system injects the fuel directly into the combustion chambers at a pressure of 120 bar. The vacuum-controlled charge tumble flaps in the CVTS flange impart a tumbling motion to the intake air at engine speeds of up to 3,500 rpm – this circular motion perpendicular to the cylinder axis enhances combustion efficiency.

In combination with turbocharging, FSI becomes TFSI – bringing together two technologies that complement one another perfectly. The swirling of the fuel helps to absorb heat from the combustion chamber walls – this solves the old problem of high heat build-up in turbocharged engines. In the V10 for the RS 6 Avant, the Audi engineers have implemented an unusually high compression ratio of 10.5:1, which produces excellent combustion efficiency. This is why the V10 biturbo contents itself with standard-cycle fuel consumption of 14.0 liters of premium gasoline per 100 km – very good fuel efficiency considering its power potential. Exhaust gas after-treatment is accomplished by means of two preliminary and two main catalytic converters. Thanks to their proximity to the engine, they rapidly reach operating temperature, and thus full effectiveness, after the engine is started.

Audi’s TFSI technology has garnered an outstanding series of victories in motor sport. The R8 racer equipped with it drove to five overall wins in the Le Mans 24 Hours as well as numerous successes in other events. In the Audi RS 6 Avant, the TFSI engine is managed by a highly advanced Motronic system called the MED 9.1.2. It operates with ten individual pencil coils and two separate control units in accordance with the master/slave principle. For the first time in this class, engine load is measured by a pressure sensor in the intake manifold.

Piling on the pressure – the two turbochargers

The single-stage intake manifold made from pressure die-cast aluminum is equipped with a multifunctional cover and features two separate air paths with two turbochargers and air filters. The pressure sensor built into the intake manifold supplies the necessary data for the innovative p/n control system. The two integral turbocharger modules – one per cylinder bank – develop pressures of up to 0.7 bar. At full load, they have the theoretical capacity to compress 2,200 cubic meters of air per hour. The clamping flange joints allow optimum longitudinal thermal expansion of the integral modules, and the kind of continuous insulation shell used in aerospace engineering minimizes energy input into the engine compartment. The turbochargers and the entire air intake system have been optimized for spontaneous, virtually instantaneous response, and suitably sized intake apertures in the front apron provide the airstreams for the two large charge air coolers.

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.

Article Index:

Text: At-a-GlanceEngineDrivetrainChassisStylingInteriorFeaturesThe RS Models

Photo Gallery: Audi RS 6 Avant

Discussion Forum: Audi RS 6

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