Engine
The new twelve-cylinder TDI, produced at the Györ plant
in Hungary, is a member of the current family of V diesel engines from Audi,
which up to now was restricted to 6 and 8-cylinder units. As with other inline
engines, it has a spacing of 90 millimeters (3.54 inches) between cylinder
centers. Yet its included angle is 60 degrees, not 90 - the reason is that
on this layout of V12, no free inertial forces or mass moments of inertia
can then occur. The results are refined in every respect. The 83.0-millimeter
bore (3.27 inches) and 91.4-millimeter stroke (3.60 inches) of the
twelve-cylinder are the same as the 3.0 TDI, producing a total displacement
of 5,934 cc. The two cylinder banks are positioned opposite one another with
an offset of 17 millimeters (0.67 inch). Measuring 684 millimeters (26.93
inches) in length the powerful engine is extremely compact, only 166 millimeters
(6.54 inches) longer than the V8 TDI. This dimension was the key prerequisite
for integrating the V12 into the Audi Q7. The V12 TDI crankcase is made from
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 crankshaft forged from chrome-molybdenum
alloy steel is mounted with the aid of an extremely rigid main bearing bridge
made of nodular cast iron. The forged connecting rods are cracked and the
pistons are made of aluminum. The two cylinder heads are each made from three
main elements. The base section is made from a high-strength, lightweight
aluminum alloy, through which the coolant flows and where the intake and
exhaust ports are incorporated. Above this are an oil-bearing upper section
and a reinforcing ladder-type frame supporting the two camshafts. The valves
are actuated by low-friction roller cam followers. The compression ratio
is 16.0:1. As usual on the Audi V engines, the no-maintenance chain drive
is mounted on the reverse of the engine, where it occupies little space.
However, it has a new layout: the camshaft's sprocket engages in an intermediate
gear via which two simplex chains drive the camshafts. Two additional chains
drive the oil pump and the high-pressure pumps for the common rail injection
system - an important innovation for the V12 TDI.
2,000 bar: common rail technology with a new
level of performance
The two twin-plunger high-pressure pumps have been completely redeveloped.
They can create pressures as high as 2,000 bar in the rails - up to now 1,800
bar was the norm. The piezo injectors with their eight-hole nozzles, each
with a diameter measuring only 0.12 millimeters (0.005 inch), have also undergone
a fundamental reworking. The high pressure creates an extremely precise spray
pattern in the combustion chambers that permits a faster, more homogeneous
and therefore more acoustically refined ignition process. The highly efficient
combustion process also increases power output, cuts consumption and reduces
pollutant emissions. The current generation of so-called inline injectors
utilizes the piezo effect: piezo crystals expand in a fraction of a millisecond
when an electrical voltage is applied. Over 300 piezo disks are packed into
the V12 TDI injectors, which use the expansion to initiate the injection
process directly. Each actuation takes just a few milliseconds - at 100
milliseconds, the wink of an eye lasts much longer. The number of injection
processes per operating cycle can be varied across a wide range thanks to
piezo technology - reaching as many as five fuel injection operations. One
to two pilot injections ensure smooth engine operation in all load and speed
ranges. Delayed post-injection serves to increase the temperature of the
exhaust gas in order to regenerate the two particulate filters included as
standard. The two turbochargers are located on the outside of the engine's
vee, each of them supplying one bank of cylinders. Thanks to their variable
vane geometry the full exhaust flow is directed through the turbines at all
times - the turbochargers respond even at low engine speeds and achieve a
high level of efficiency.
2.7 bar: high boost pressure
Both turbocharges generate up to 2.7 bar of absolute boost pressure. Two
large intercoolers reduce the temperature of the compressed air and thus
increase the level of oxygen required for combustion. The V12 TDI features
a dual-branch intake system. For each bank of cylinders there is an air filter,
behind which an air mass meter is located. Two ultra-fast control units manage
events in the engine, sharing the workload according to a master/slave principle.
The six-liter has adopted map-controlled swirl variation of the combustion
air from its smaller TDI siblings. The electrically controlled flaps can
be adjusted to ensure optimum swirl with respect to high performance and
low emissions. The exhaust system also has a dual-branch design; here Audi
engineers focused their attention on exhaust gas recirculation. At partial
throttle, up to 50 percent of the exhaust is fed back into the intake air
in order to reduce NOx emissions. The large-dimension recirculation system,
located at the top of the inner vee, incorporates a water cooler that uses
map-based control to lower the temperature of the exhaust gas. With its 368
kW (500 hp) the diesel generates a specific power output of 62.0 kW (84.3
hp) per liter of capacity - worthy of a sports car. Even more impressive
is its maximum torque: between 1,750 rpm and 3,250 rpm the V12 TDI has a
constant 1,000 Nm (737.56 lb-ft) on tap - this amounts to 168 Nm (123.91
lb-ft) per liter of capacity. The 11.3 liters of fuel that the potent TDI
requires on average per 100 km (20.82 US mpg) is a reflection of its superior
efficiency. This figure is even more astounding when compared with gasoline
engines offered by the competition - the fuel consumption of these units
is much higher all-round.
Transmissions
The mighty engine power of the V12 TDI flows through a fast and extremely
smooth-shifting six-speed tiptronic, which was specially designed for the
immense torque of the six-liter diesel. The driver can shift the gears of
the automatic transmission either manually with the selector lever or with
the standard chromed shift paddles on the three-spoke leather-covered steering
wheel. The quattro drive distributes the power to the front and back wheels
in a 40:60 ratio - giving the vehicle a sporty, rear-focused driving style
that guarantees maximum agility and driving enjoyment. When needed, the
inter-axle differential transfers most of the power to the axle with better
traction. Great care has also been devoted to reinforcing all key components
in the quattro driveline.
Chassis
The chassis of the Audi Q7 V12 TDI quattro is a marvel of high-tech
construction. Double wishbones guide the front and rear wheels; the axle
components are made primarily of aluminum. Thanks to the extreme precision
and directness of the servotronic steering, the driver remains in close contact
with the road. This is where the handling characteristics, driving safety
and comfort of the performance SUV set the benchmark. Even in rough terrain
the Audi Q7 V12 TDI quattro can easily cope with the challenges - with a
maximum ground clearance of 240 millimeters (9.45 inches). The ESP stabilization
system features hill descent assist and a special off-road mode which optimizes
traction. The standard adaptive air suspension works with sporty new tuning.
In combination with electronically controlled shock absorbers incorporating
dynamic roll stabilization, the air suspension can be adjusted in three zones
ranging from extremely comfortable to highly dynamic. The driver can also
adjust ground clearance in five stages via this system and lower the tail
end by 71 millimeters (2.80 inches) for comfortable loading. The ultimate
performance SUV from Audi is fitted with sporty 20-inch cast aluminum wheels
with a ten-spoke design. Alternatively, wheels with a 20-spoke design are
available, as are impressive 21-inch wheels in a choice of three different
designs. Behind the large wheels is a powerful 20-inch brake system. Made
of ceramic reinforced with carbon fiber, the internally ventilated disks
are notable for their low weight, robust performance and minimum wear. As
on a high-performance sports car, eight-piston calipers grip the disks at
the front axle, while the rear brakes each have four pistons. The calipers
are painted in Titanium Gray - the front ones bear the lettering "Audi ceramic".
Design
The visual styling of the Audi Q7 V12 TDI quattro gives the vehicle an
unmistakable look. Daytime running lights consisting of twelve white LEDs
per headlight announce the vehicle's presence even at a distance. They are
located on the upper edge of the air intake slots, replacing the turn signals
that were moved to the bi-xenon headlights. Further honing the vehicle's
profile are vertical chromed bars in the grid of the single-frame radiator
grill and an underbody protector made of stainless steel. The newly designed
bumper groups the highly polished side air intake slots into large units.
When viewed from the side, both the 20-inch wheels and the matt aluminum
caps on the exterior mirrors catch the eye. The wheel arches have been widened
a total of 26 millimeters (1.02 inches) at the front and 30 millimeters (1.18
inches) at the rear; the lower edges of the doors flaunt striking new moldings.
The windows are framed by matt aluminum cover strips; the roof rails sport
the same look. The taillights are set in a dark-colored background, while
the newly designed bumper incorporates two large, oval exhaust tailpipes.
At the rear, the underbody protector is also made from stainless steel. A
metallic or pearl effect finish comes as standard. The Q7 V12 TDI quattro
impresses with its elegant and dynamic styling. The ultimate performance
SUV from Audi has a powerful and elongated look; with a length of 5,063
millimeters (199.33 inches), a width of 2,000 millimeters (78.74 inches)
and a height of 1,737 millimeters (68.39 inches) it boasts the sportiest
dimensions in its class. High side panels lend the vehicle body a muscular
appearance, particularly in contrast with the flat, sporty window area. The
dynamic line above the wheel arches, the powerful shoulder section and the
flowing roof line together with the standard roof rails underline the vehicle's
athletic looks. The pronounced tapering of the front section and the rear
end with its sharply sloping D-posts fashion a coupe-like silhouette. The
interior and the cockpit area create a sense of light and airy spaciousness,
perfect ergonomics and excellent quality. Audi offers customers a choice
of four, five, six or seven highly versatile seats. Depending on seating
capacity, the cargo area can hold up to 2,035 liters (71.87 cubic feet).
Aluminum inlays shine in the door sill trims and the carpet is made of velour.
Carbon fiber covers and the aluminum-look selector lever give the center
tunnel a high-tech ambience, exclusive wood trim is available as an option.
The buttons of the MMI operating system, which has proven a superior concept
in numerous independent tests, gleam in silver, the air vents in aluminum,
the pedals and footrest in stainless steel. Verano leather covers the
electrically adjustable sport seats; the deluxe center armrest and the armrests
in the doors are upholstered with leather as well. The front and rear seats
can be heated; a special lighting package softly illuminates the interior.
Equipment
Also included in the luxurious standard specification for the
Audi Q7 V12 TDI quattro are the leather package, leather multifunction sports
steering wheel, black roof lining, folding exterior mirrors, DVD navigation
system, Bose Surround Sound system with CD changer, Bluetooth mobile phone
preparation, alarm system and tire pressure monitoring system. The tailgate
opens and closes electrically - it partly overlaps the D-posts, lending a
muscular look to the rear end. The standard deluxe automatic air conditioning
regulates heating and ventilation separately for the driver's and front
passenger's side, taking sunlight levels into account at the same time. Audi
offers four optional high-tech assistance systems for the Q7 V12 TDI quattro:
adaptive cruise control, Audi lane assist and Audi side assist help the driver
to maintain the correct distance from the vehicle in front, stay in lane
and change lanes. Audi parking system advanced includes a camera to monitor
the area behind the vehicle. The multimedia system becomes even more versatile
with the optional Audi music interface, a convenient connection point for
the customer's iPod. Available on request is the Advanced Sound System from
Bang & Olufsen, which offers a totally unparalleled sound experience.
The leather package advanced offers even more comfort in the interior, and
includes exclusive coverings for the dashboard and centre console. The large
glass sunroof - the open sky system - and a rail system for the cargo area
further enhance the appeal of the Q7 V12 TDI quattro as a touring vehicle.
The Q7 V12 TDI quattro, the exclusive top model in the series, makes its
way to dealers towards the end of 2008.
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 excepted. |