2007 Audi A6 Allroad

Engine

 A total of four power units are available for the new A6 allroad quattro – two petrol and two TDI engines, each installed longitudinally. High reserves of power and muscular torque are common to all four engines, which stem from Audi’s state-of-the-art family of V-engines. These are designed around a cylinder angle of 90 degrees and cylinder spacing of 90 millimetres for an extremely compact basic layout. Further characteristics shared by the four powerplants include the maintenance-free chain drive for the camshafts and the low-friction valve gear using roller-type cam followers.

Continuous adjustment of all four camshafts and a variable intake manifold optimise mixture preparation in the two petrol engines – both of these techniques pave the way for high power combined with beefy torque. The cylinder blocks are made from light alloys, ensuring that both petrol units are amongst the lightest on the market – a key advantage which directly benefits the overall weight of the Audi A6 allroad quattro and its axle load distribution.

Two V6 diesel engines with displacements of 3.0 and 2.7 litres which made their debut in the A6 will be available for the new A6 allroad quattro, too. The two engines both use four valves per cylinder and are part of Audi’s new V-generation line-up. Featuring a chain drive for the camshaft and oil pump, they boast extremely compact dimensions.

The engines measure just 444 mm in length, while the 3.0 TDI unit weighs in at a mere 219 kg, making it one of the lightest diesel engines in its class. This is largely down to the use of an ultra-high-tech material for the cylinder blocks: high-strength vermicular-graphite cast iron.

To ensure an optimum throughput of air, the turbochargers in the two V6 diesel power units work on the principle of variable turbine geometry. Mixture preparation is the task of a latest-generation common-rail system, featuring a high-pressure pump and a rail for each bank of cylinders. The high injection pressure of as much as 1,600 bar results in even finer atomisation of the fuel, meaning superior mixture preparation and more efficient combustion.

The 3.2 FSI boasts all the same credentials of an ultra-modern engine that can be found in the V8. And, just like its larger sibling, it too has been designed for maximum space efficiency. Measuring only 360 mm in length and 430 mm in width, and weighing a mere 169.5 kg thanks to its aluminium construction, the engine offers tangible benefits in terms of handling characteristics. The cylinder bore of 84.5 mm and stroke of 92.8 mm – precisely the same dimensions as on the V8 FSI – add up to an overall engine capacity of 3,123 cc.

Fine-tuning of the exhaust system produces a distinctly sporty, classic V6 sound that is never intrusive however, making the qualities of the engine a truly sensory experience for the driver. The V6 power unit offers instantaneous throttle response and races all the way up to the red line at 7,200 rpm with consummate ease.

The 3.2 FSI delivers its maximum output of 188 kW (255 bhp) at 6,500 rpm; its peak torque of 330 Nm is available at just 3,250 rpm. Over 90 percent of the engine’s maximum torque is continuously available across a wide rev range from 2,400 to 5,500 rpm – an unprecedented characteristic for a naturally aspirated V6.

Partnered by the 6-speed manual gearbox, the V6 power unit catapults the A6 allroad quattro to 100 km/h in 7.2 seconds and on to a top speed of 242 km/h. Average fuel consumption is 11.0 litres of premium-grade fuel per 100 km, providing yet further evidence of the capabilities of the FSI technology. The corresponding figures for the 6-speed tiptronic transmission are 7.7 seconds, 240 km/h and also 11.0 litres per 100 km

With a capacity of 4,163 cc, the V8 FSI power unit that is now making its debut in the A6 range is derived from the engine in the Audi Q7 and is also a close relation of the powerplant which can be found under the bonnet of the mighty Audi RS 4. The reduction in the maximum rev speed means that the version in the A6 allroad quattro delivers 257 kW/350 bhp at 6,800 rpm. Torque, on the other hand, is even more abundant than in the RS 4, peaking at 440 Nm at 3,500 rpm. 85 percent of maximum torque is on tap as low down as 2,000 rpm.

The V8 engine’s cylinder block is based on a bedplate structure, where all of the crankshaft bearings are held together in a subframe for extra reinforcement. The crankcase is cast from an aluminium/silicon alloy, with the pistons sliding along the hard silicon crystals inside the cylinder liners. There is no need to insert separate liners allowing the use of bore bridges that are just 5.5 mm wide, a low overall weight and an overall length of just 464 mm.

The four camshafts are driven by a low maintenance double-stage chain drive consisting of three simplex roller chains. It is fitted in a space-saving location on the rear face of the engine, reducing the overall length by a whole 52 mm. A fourth chain drives the ancillaries.

The V8 power unit features a two-stage variable intake manifold made of magnesium. Two high-pressure pumps driven by the intake camshafts feed the petrol to two interconnected stainless steel rails. The petrol is then injected directly into the combustion chambers via the injector valves. The entire process is managed by a single control unit from Bosch – the Motronic MED 9.1.1, one of the most sophisticated units on the international market.

The prodigious power reserves of the V8 FSI unit bestow the new Audi A6 allroad quattro with performance on a par with a sports car. The sprint from standstill to 100 km/h is over in a fleeting 6.3 seconds; top speed is limited to 250 km/h. The sublime V8 is available exclusively in conjunction with tiptronic.

Thanks to the super-efficient FSI technology, consumption is just 11.2 litres of Super Plus per 100 km; the V8 will also run on premium unleaded petrol, albeit with a slight loss of power. It goes without saying that the V8 FSI engine meets the EU4 emissions standard. Two close-coupled multi-stage catalytic converters are integrated into the exhaust system in a compact manifold/catalytic converter module. Tubular sheet-metal manifolds with air-gap insulation are designed for extra-fast activation of the catalytic converters, ensuring that exhaust emission control starts as quickly as possible after the engine has been switched on.

A veritable powerhouse is available for the A6 allroad quattro in the guise of the 3.0 TDI. Delivering 171 kW/233 bhp at 4,000 rpm and 450 Nm, this diesel unit is able to call upon vast reserves of output and torque from its capacity of 2,967 cc. Maximum torque is available from a mere 1,400 rpm, giving the driver phenomenal pulling power throughout the rev range.

For optimum charging of the cylinder under all operating conditions, the engine has a turbocharger which is accommodated inside the "vee" to make the best use of the available space. Two intercoolers running in parallel reduce the temperature of the intake air drastically, further optimising cylinder charging. The high-speed glow plugs in the combustion chambers are designed to operate in extreme cold, heating up to a temperature of 1,000 degrees within the space of just two seconds.

The exhaust gas is purified by a close-coupled preliminary catalytic converter – located close to the turbocharger – and the main underfloor converter. As a result of all these measures, the A6 allroad quattro 3.0 TDI comfortably undercuts the limits imposed by the EU4 emissions standard. As on the 2.7 TDI, a diesel particulate filter is included as standard in Germany.

The Audi A6 allroad quattro 3.0 TDI is available with a choice of a 6-speed manual gearbox and the 6-speed tiptronic transmission. It covers the standard 0 100 km/h sprint in just 7.5 seconds (with tiptronic 7.8 s); top speed is 231 km/h (with tiptronic 230 km/h). The mighty diesel exercises extreme restraint when it comes to its fuel consumption however, requiring just 8.4 litres per 100 km (tiptronic: 8.8 l).

Fun yet economical, refined and ecological: the 2.7 TDI is an extremely gifted all-round talent. It also lists high output and abundant torque amongst its strengths, and combines them with excellent fuel efficiency.

Reducing the stroke by 8.3 mm to 83.1 mm whilst leaving the bore unchanged at 83.0 mm results in an overall swept volume of 2,698 cc. The vital performance statistics read as follows: an output of 132 kW (180 bhp) across an engine speed range of 3,300 to 4,250 rpm and a peak torque of 380 Nm available from just 1,400 rpm all the way up to 3,300 rpm – as far as the driver is concerned, this translates into remarkable power in virtually any situation. The highly refined acoustics are just another of the 2.7 TDI’s many virtues.

The time of just 9.3 seconds for the sprint from standstill to 100 km/h testifies to the dynamism of the 2.7-litre diesel model; the fuel consumption figure of 8.7 litres per 100 km bears witness to its fuel efficiency. The 2.7 TDI engine is coupled with the silky smooth 6-speed tiptronic transmission.

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