2004 PORSCHE 911 TURBO four wheel drive

· 14 ·· 15 ·The new 911 Turbo |
The new 911 Turbo
The second 911 Turbo, launched
in 1977, developed 300 bhp from
a 3.3-litre intercooled engine.
Brake performance was similarly
enhanced, combining four-piston
aluminium fixed calipers with
cross-drilled discs.
In 1993, Porsche launched the
final 911Turbo to feature dedicated
rear-wheel drive. Based on the
Type 964 platform, it used a
3.6-litre engine to achieve a major
boost in output to 360 bhp.
Its Type 993 successor, launched
in 1995, set a range of new
benchmarks in supercar perform-
ance. All-wheel drive provided
greater active safety as well as
better driving dynamics. The
system also had a rear-axle bias
that retained the familiar Porsche
handling characteristics. Twin
exhaust turbochargers offered
better response and a more
harmonious build-up of power. The
last 911 Turbo to have an air-
cooled engine, it offered maximum
output of 408 bhp from a
3.6-litre displacement.
The first water-cooled 911 Turbo,
the Type 996, made its debut
in the year 2000. Also equipped
with all-wheel drive, it used
VarioCam Plus to achieve a major
improvement in all-round fuel
economy. The engine capacity
remained at 3.6 litres, while
output rose to 420 bhp fo r a
maximum speed of 305 km / h
(190 mph). The Type 996 model
was the first 911 Turbo with the
option of Tiptronic S transmission.
The subsequent launch of the
Turbo S version saw a further
rise in output to 450 bhp.
Now, the evolution of this
remarkable car has reached a
new pinnacle of achievement.
Over the following pages, we
will explore every aspect of the
new 911 Turbo.The first Porsche racing car to
feature turbocharged power made
its debut in the early 1970s. The
12-cylinder engine in the legendary
917 used a twin turbo system to
achieve a colossal 1,000 bhp
.
In 1972, the 917/10 with 5-litre
turbo engine claimed the North
American CanAm
championship.
In the following season, the
917/30, developing 1,100 bhp
from a 5.4-litre unit, became the
most powerful racing Porsche of
all time.
This invaluable race experience
inevitably found its way into our
production
road car development.
Just one year later, in 1974,
the 911 Turbo was born. Preceded
as it was by the 1973 oil crisis, it
was considered a
bold undertakingby Porsche. As history would show,
it was the first of many surprises in
the evolution of this legendary car.
The original 911 Turbo featured
widened wheel arches as well as
specially developed front and rear
spoilers. These major aerodynamic
refinements were essential
requirements given the increased
engine performance. Developing260 bhp, the first 911 Turbo could
reach 100 km / h (62 mph) in as
little as 5.5 seconds. Maximum
torque output of 343 Nm was
unprecedented in a 3-litre engine.
This exceptional performance
necessitated a new gearbox
design featuring specially
reinforced gears. Thus began a
new type of Porsche that would
soon acquire mythical status.
911 Turbo 3.0 (1974), 911 Turbo (2006)

are reduced thanks to lengthy
replacement intervals for both
the engine oil (18,000 miles) and
air filter unit (36,000 miles). The
spark plugs require changing after
36,000 miles or a maximum of
every four years. The generator,
power-steering pump and air-
conditioning compressor are all
driven by a single self-adjusting
belt with a service life of 54,000
miles. The hydraulic tappets
provide automatic adjustment of
all valve clearances, while the
drive chains on the camshafts
and auxiliary shafts will also last
the life of the car.
Basic servicing is required after
18,000 miles or a maximum of
two years on the road. The first
major service is due at 36,000
miles or every four years at the
latest. The results: lower running
costs and virtually uninterrupted
enjoyment from your Porsche.
Exhaust system.
The exhaust system on the
911 Turbo is made from highly
durable stainless steel. The
system consists of two separate
tracts, one for each bank of
cylinders. The catalytic converters
are extremely heat-resistant,
yet quick to reach temperature
(and thus optimum performance)
when the engine is started
from cold.Twin lambda sensors in each of
the exhausts enable continuous
monitoring of the combustion
process. An additional pair of
sensors* is used to measure
the efficiency of the catalytic
converters.
Servicing.
Another pleasant surprise on the
new 911 Turbo is the standard
service schedule. Running costs
The new six-speed manual
gearbox in the 911 Turbo is
specifically adapted to the car’s
high levels of engine torque.
Designed primarily for sports
driving, one immediate
characteristic is the perfectly
judged spread betweensuccessive ratios as you upshift
through the gears. The gearshift
throw is short and precise,
with only minimal force required.
Thanks to a dual-mass flywheel,
this uncompromising setup means
there’s never any compromise
in comfort. The linkage provides
a direct connection with the
gearbox while insulating
the lever from engine vibration.
One final detail – the new gear
lever design – is exclusive to
the 911 Turbo.
· 44 ·· 45 ·The new 911 Turbo |
Drive
Six-speed manual gearbox.
Superlative power requires equal precision.
Gear lever exclusive to 911 Turbo* Not in markets with leaded fuel.

using the automatic brake
differential (ABD) function. For
optimum traction, manual gearbox
cars can also be equipped with
an optional mechanical limited-slip
rear differential (see page 56).
Assisting PTM is a new and
specially uprated version of
Porsche Stability Management
(PSM – see page 58). Combined,
these systems ensure optimum
torque distribution – and thus
optimum drive – in every type of
road scenario, including high-
speed straights, hairpin bends and
challenging, variable-grip surfaces.
Under heavy braking where ABS
is required, the multi-plate clutch
severs all front drive so that
each front wheel can be controlled
separately
by the ABS without
being influenced by the rear wheel
dynamics.
The traction benefits of the new
electronically controlled system
are particularly apparent in
the wet or on snow. In these
conditions, the new 911 Turbo
offers breathtaking acceleration.
In short, PTM offers greater
active safety, greater performance,
and even more of the positive
handling and agility you’d expect
from a 911 Turbo.
· 49 ·The new 911 Turbo |
Drive
differential (ABD) and anti-slip
regulation (ASR).
The electronically controlled clutch
is used to vary the drive torque
transmitted to the front axle. The
previous 911 Turbo had a multi-
plate clutch filled with a viscous
fluid, which ‘passively’ determined
the front/rear torque split. On
this latest evolution, the fluid is
replaced by active, electronic
control.While the viscous-fluid system
responds to relative differences in
front/rear axle speed, the new
electronic clutch offers a more
direct response to changing road
scenarios. The status of the car
is continuously monitored with the
aid of on-board sensors. These
are used to measure a range of
values, including the rotational
speed of all four wheels, the lateral
and longitudinal acceleration of
the car, and the current steering
angle. The sensor data is analysed
in ‘real time’ by PTM, enabling
immediate adjustments in front-end
drive torque as and when required.
If, for example, the rear wheels
lose traction under acceleration, a
greater proportion of drive torque
is automatically transmitted to
the front axle. The integral ASR
function is also used to minimise
wheel-spin. When
cornering,
the system controls drive to the
front wheels in order to maintain
optimum lateral grip. On variable-
grip surfaces, traction is enhanced
· 48 · Electronically controlled multi-plate clutchAll-wheel drive system
Genuine high performance calls for
more than just a powerful engine.
It also requires an effective means
of applying that power to the road.
On the 911 Turbo, this is achieved
by means of permanent all-wheel
drive and an all-new version of
Porsche Traction Management
(PTM). The key mechanical feature
within the AWD system is the
electronically controlled multi-plate
clutch. Integral functions within
PTM include an automatic brake
Electronically controlled all-wheel drive with Porsche Traction Management (PTM).
The intelligent application of power and torque.

The new 911 Turbo is equipped
with Porsche Active Suspension
Management (PASM) as standard.
This electronic active damping
system offers continuous adjust-
ment of the damping force on
each wheel based on current road
conditions and driving style.
PASM has two driver-selectable
setup modes, ‘Normal’ and ‘Sport’,
which share a minimal degree
of overlap. While ‘Normal’ provides
a blend of performance and
comfort, the ‘Sport’ setup mode
has a much firmer range of
settings. The system responds to
changing road conditions and/or
driving style by continuously
varying the individual damping
forces within the parameters
defined for the selected setup
mode (‘Normal’ or ‘Sport’).
PASM uses a range of sensors
to monitor any movement in the
body of the car (e.g., under
acceleration, braking or on uneven
road surfaces). The PASM control
unit uses this data to obtain a
real-time evaluation of the forces
acting on the car. The system
responds continuously with a
corresponding modification of
individual damping force s in
accordance with the selected
setup mode. The results are a
reduction in both pitch and roll
as well as consistent road-holding
from all four wheels.
If ‘Sport’ mode is selected, the
suspension is set to a harder
damper rating. If the quality of
the road surface falls below a
certain threshold, the system
immediately changes to a softer
rating within the ‘Sport’ setup
range. This adjustment enhances
occupant comfort as well as
traction and grip. When the road
surface improves, PASM
automatically reverts to the
original, harder rating.
If ‘Normal’ mode is selected, and
the car is driven more assertively,
PASM automatically switches to
a harder rating within the ‘Normal’
setup range. As the dampers
become stiffer, the car becomes
more stable, ensuring higher
levels of active safety as well as
greater enjoyment from your
Porsche.
Limited-slip differential.
The manual gearbox version of
the new 911 Turbo is available with
an optional mechanical limited-slip
rear differential. Key benefits
include greater rear-end traction
when exiting hairpin bends as
well as on variable-grip surfaces.
It also compensates for changes
in wheel loads caused by throttle
modulation when cornering.
· 56 ·· 57 ·The new 911 Turbo |
Chassis
Porsche Active Suspension Management (PASM).
From ultimate comfort to optimum performance,
all at the push of a button.
Rebound in ‘Normal’ mode –
damper piston with bypass
valve openRebound in ‘Sport’ mode –
damper piston with bypass
valve closed
Compression in ‘Sport’ mode –
damper piston with bypass
valve closedCompression in ‘Normal’ mode –
damper piston with bypass
valve open