|September 26, 2000
Twelve Cylinders for the A8
At the Paris Motor Show Audi is presenting a vehicle full of superlatives - the new A8 L 6.0 quattro. This luxury saloon is powered by an aluminium twelve-cylinder engine with a capacity of six litres, which develops 309 kW (420 bhp). This engine thus qualifies as the largest capacity and most powerful production twelve-cylinder engine ever to be found in a saloon car worldwide. And it also sets standards in terms of torque: the new Audi engine produces 550 Nm - this also surpasses any other production saloon in the exclusive twelve-cylinder league.
The A8 6.0 L quattro requires less than six seconds to sprint from 0 to 100 km/h; the most powerful German twelve-cylinder car of the modern age reaches its electronically governed top speed of 250 km/h after scarcely 38 seconds. The most impressive thing about it of course is just how spontaneously the 6-litre engine translates every command issued at the throttle into acceleration, and just how smoothly it revs up to the rated speed of 6000 rpm.
At the same time more than 90 percent of the engine's peak torque is available at just 2500 rpm; the ideal basis for supreme pulling power in every velocity range. The torque characteristic of this large-capacity naturally aspirated engine is without comparison.
The five-speed tiptronic makes sure that exactly the right amount of power is always available. And it additionally offers the driver the chance to intervene actively in the manual shift gate or - as an option - by pressing the button on the leather-rimmed multifunction steering wheel.
Lightweight construction and agility
A thoroughbred Audi, the A8 L 6.0 quattro has more exclusive qualities to offer than sheer power and performance alone, setting it apart from all competitors. It is the only twelve-cylinder model with the aluminium Audi Space Frame ASF. This pioneering lightweight technology made its debut in 1994, and has since opened up a unique perspective for responsible mobility in the luxury class. The consistent reduction in vehicle weight thanks to ASF improves performance and cuts fuel consumption.
Thanks to its low unsprung masses, the aluminium suspension on the Audi A8 gives it unique driving potential. The wheel carriers, front and rear control arms, all brake callipers, the shock absorber mountings and wheels are all made of aluminium. This suspension concept, which is unmatched by the competition, also has a positive effect on comfort. The vibrational behaviour of the axles produces a level of ride and suspension comfort that is without comparison. And the insulation against suspension noise is also exceedingly effective on the Audi A8.
The Audi A8 L 6.0 quattro is the only twelve-cylinder saloon car to have quattro permanent four-wheel drive. This enables it to translate its advantage in terms of power into supreme performance and superior dynamic handling characteristics. There's no doubt about it: the Audi A8 L 6.0 quattro is the sportiest of all luxury saloons. The flagship of the A8 series and of the Audi brand presents itself as befits its status, as a vehicle to which there is no alternative.
Compact power plant
Audi is currently the only manufacturer to use a twelve-cylinder engine in the form of a double "V" or "W" in series production. This design principle has one inestimable advantage: despite the larger number of cylinder units, despite a clearly higher displacement, the W12 is as compact as a V8 and thus has much smaller dimensions than a conventional V12 engine.
This engine can only be combined with quattro four-wheel drive thanks to its unusually short length of 513 millimetres together with a width of 690 millimetres. All other twelve-cylinder engines installed at the front of the car can only drive the rear wheels - in this case there is not enough space under the bonnet for additional front-wheel drive components.
Another advantage of this compact design - together with the choice of the light metals aluminium and magnesium - is the very low weight of the Audi twelve-cylinder engine. And this in turn helps to produce an unbeatably low total vehicle weight of 1980 kilograms, lighter than any of its competitors. One horsepower on the Audi A8 L 6.0 quattro has to accelerate just 4.7 kilograms - a figure which can compete with a high-performance sports car.
The W principle
The new Audi twelve-cylinder engine is unparalleled by past technology - despite the fact that there have already been examples of this W-engine design in automotive history. The legendary 1920s Rumpler "tear-drop" car, for example, for which its designer developed a six-cylinder engine in 3x2 formation. Or, just a few years later, the world record car driven by Campell, Seagrave and Cobb: this was powered by a W12 aircraft engine with a capacity of 24 litres and 502 bhp.
And Audi too has already made use of a W12 engine: it produced 509 bhp in the legendary Avus super sports car study, presented in 1991.
A direct comparison with these engines clearly reveals the special feature of the Audi engine. Unlike its historical predecessors, it is not a W-engine in the classic sense with three separate cylinder banks. In this case, three connecting rods are mounted on a single crankpin. The new twelve-cylinder engine, which the Audi design engineers have developed together with their Volkswagen colleagues, is different.
A glance at the engine's cylinder blocks shows that two ultra-compact V6 units are combined to produce an engine. Each of the two cylinder rows contains six cylinders at an angle of 15 degrees. This offset arrangement makes an ideal synthesis of the very compact width - compared with the classic V6 - and the very short length of a four-cylinder engine.
Joining these two units at an angle of 72 degrees to produce a twelve-cylinder engine has a third advantage: the height of the engine is considerably less than that of a "genuine" W12, which means that the silhouette of the front end of the car can be made flatter and more aerodynamic.
And, a further advantage, the unmistakable sporty aura of the Audi A8 design has thus also been retained in the top-of-the-range version, where perhaps it is most expected.
Another advantage of this design is the high rigidity of the engine as a whole. This translates into excellent vibrational comfort which surpasses even the high level expected of a twelve-cylinder engine.
The heart of the W12 engine is the crankshaft running in seven bearings which weighs just 20.5 kilograms. The crankpins are offset to achieve a constant firing order as on a V6 engine.
With dry sump lubrication
As a gesture of respect to its particularly high performance, Audi's W12 engine has dry sump lubrication. In contrast to conventional wet sump lubrication, the oil pumps supplies the engine with oil from a separate oil tank. This is turn can be optimised in terms of design compared with a conventional oil sump.
The oil tank on the Audi W12 engine is situated behind the right headlight - looking towards the front of the car - and is connected to the engine by two hoses.
The oil pump is driven by a chain directly from the crankshaft. A water cooler on the left side of the engine near the oil sump ensures efficient oil cooling.
This is a system rarely found on production vehicles, in just a few high-performance sports cars. The greatest advantage of dry sump lubrication is that it allows an optimum supply of oil to the engine even at high lateral acceleration levels.
Optimum charging, low emissions
Double overhead camshafts per cylinder bank are responsible for the valve gear. Driven by a single chain, they operate two inlet and two exhaust valves per cylinder via low-friction roller cam followers: a principle which helps not least to reduce fuel consumption noticeably. The camshafts can be adjusted variably - by 52 degrees at the inlet valves and 22 degrees at the exhaust valves - which means that the optimum valve timing can be realised across the entire engine-speed range. It is thus possible to achieve good idle-speed quality, low crude emissions and ample torque across the speed range.
Mixture preparation is performed by the Bosch Motronic ME 7.1.1 with electronic, sequential injection. This system includes electronic throttle control, hot-film air-mass sensing, cylinder-selective knock control via four sensors and variable lambda control.
Emissions control is the task of four 3-way catalytic converters installed near the engine, plus two 3-way primary catalytic converters in the region of the silencer. Eight heated lambda sensors continually monitor the exhaust gas. As a result, even such a powerful engine as this has no trouble satisfying the emission limits according to EU III.
Genuine twelve-cylinder sound
There's no doubt about it: a large part of a successful twelve-cylinder engine's fascination is its very special sound. Audi thus also placed a great deal of emphasis during development on these specific acoustic qualities.
This means, on the one hand, an excellent, extremely low-vibration idle-speed quality and a particularly low noise level during partial-load acceleration and at constant vehicle speeds. At the same time, Audi's acoustics engineers have composed an extremely sporty, powerful sound pattern, albeit with a refined touch, for this engine for part-load acceleration. This unmistakable sound design combines the demand for maximum acoustic quality with the emotional and dynamic component, which ultimately also typifies the overall character of the vehicle in conjunction with its excellent performance.
These acoustic strengths are based on a particularly smooth-running engine, for which several components are responsible: the dynamically optimised crankshaft and camshaft drives and the particularly rigid design of crankcase and transmission connection. Finally, the engine developers performed the acoustic fine tuning of the engine by carefully matching the intake tract, the exhaust system and also the unit mountings.
Audi A8 L 6.0 quattro - Audi's flagship
It is almost impossible to imagine a more fitting, more stylish setting for the debut of the new twelve-cylinder engine than the long-wheelbase version of the Audi A8. Power and dynamism without aggression, elegance and a clear use of forms characterise it as an incarnation of the Audi design philosophy.
Just a few features suffice to visually identify the twelve-cylinder version: viewed from the front, these include the original radiator grille which is differentiated from the Audi S8 by the vertical chrome bars.
"W12" emblems are located on the radiator grille, on the side rubbing strips and inside the car, above the glove box. At the rear of the car, the model inscription A8 L 6.0 quattro and the original design of the twin tailpipes indicate that you are looking at the flagship of the Audi model range. 18-inch forged aluminium wheels of 10-hole design and with 245/55 ZR 18 tyres point to the new Audi's dynamic potential.
Maximum comfort and an ambience of discreet luxury are the characteristic features of the interior of the most powerful and most exclusive Audi saloon. Dynamism and calm, sports character and maximum stylishness do not contradict each other in this vehicle. The standard equipment of the Audi A8 L 6.0 quattro creates a perfect composition of individuality and impeccable elegance.
Comfort seats upholstered in breathable Valcona leather offer all occupants maximum seating comfort even on long journeys. Colour coordinated tone on tone, the ambience appears both elegant and comfortable. And the surface feel of the materials used, such as leather or Alcantara, indicates their extremely high quality. Aluminium trims for roof frame and window capping strips add a clearly sporting emphasis, as do the aluminium shift gate and selector lever.
The enhanced leather trim package also includes the front and rear door trim panels, the lower half of the instrument panel and the sides of the centre console. The twin-pane glass insulates effectively against intensive solar radiation and disturbing outside noise. The deluxe automatic air conditioning, which also takes the direction of the sun into account, helps to make sure that the atmosphere inside the car is always in keeping with its occupants' requirements. And an air quality sensor in conjunction with an activated charcoal filter makes sure that the pollutant concentration in the interior is kept at a low level.
Both the two front occupants and all rear-seat passengers will find the Audi A8 L to be extremely spacious. The rear-seat occupants in particular benefit from this special A8 version's 30 millimetre longer wheelbase and from the option of also being able to adjust the fore/aft position of the front passenger's seat from the rear seat. The result is the amount of legroom which you would fully expect to find in a vehicle of such high pedigree.
The fact that a number of attributes can transform this comfort experience into the ultimate travel experience is a matter of course for Audi. The specially matched BOSE sound system with CD changer in the luggage compartment can turn even the shortest of trips into a concert tour. And optional leather cushions and foot rests create a luxurious "quiet room" in the rear compartment.
The back of the A8 can also be transformed into a mobile high-tech office thanks to the office package, which can be ordered as an option from quattro GmbH. As well as numerous convenient details, a fax machine is available, integrated into the centre armrest. A folding table on the back of the front seat can even be operated fully automatically. And thanks to the TV/video unit with LCD monitor, it is also possible to use audio-visual media on the move.
The driver can also benefit from all those features that are designed to make his work behind the steering wheel as comfortable and safe as possible. The standard navigation system Plus helps him to reach his destination without going out of his way and by taking the best route possible. Audi telematics, a new kind of service and information system, is available as an option. With the information this system provides on the current traffic situation, the navigation system can be upgraded to include dynamic route guidance: this is the perfect opportunity for all frequent drivers to avoid tailbacks, yet complete their journey without making unnecessary detours.
Audi has of course also placed considerable emphasis on the safety of this superlative vehicle. As well as front and side airbags for the driver and front passenger, the car also has side airbags for the outboard rear passengers. The occupants are also protected additionally by the head-airbag system SIDEGUARD, which covers almost the entire side window area, from the A-post to the C-post.
A tyre-pressure monitoring system checks the air pressure in the tyres while the car is moving. And the Electronic Stability Program ESP helps the driver to remain safely in command of critical handling situations by means of controlled brake and engine management intervention. Active safety is further optimised by standard-fit xenon plus headlights for low and high beam. There is no doubt this system currently offers the greatest and most even light output.
Almost 70 years ago, in the autumn of 1931, Horch presented one of the world's first twelve-cylinder production engines: a milestone in German automotive history. The traditional company Horch, one of the Audi brand's historical roots, fitted a convertible with a V12 engine which - like the new W12 - had a cubic capacity of six litres.
There is no doubt that the new Audi flagship is also a milestone in the luxury class. A vehicle for the most discerning customers looking for nothing less than technical innovation, comfort and convenience at the very highest level. We have the very thing for them: the fascination of the largest, most powerful twelve-cylinder engine in a saloon, combined with quattro four-wheel drive and the consistent lightweight design of the Audi Space Frame - the Audi A8 6.0 L quattro.