2004 PORSCHE 911 TURBO compression ratio

vanes are opened further. By
varying the vane angle, it is
possible to achieve the required
boost pressure over the entire
engine speed range. As a result,
there is no need for excess-
pressure valves as found on
conventional turbocharged
engines.
· 34 · · 32 ·· 33 ·The new 911 Turbo |
Drive
Variable Turbine Geometry (VTG).
Creating the optimum turbo for every scenario.
known as ‘turbo lag’, means there
is virtually no turbocharging effect
at lower engine speeds. To
overcome this problem, the twin
water-cooled turbochargers on
the new 911 Turbo feature Variable
Turbine Geometry (VTG). With
this technology, the gas-flow from
the engine is channelled onto Larger turbo units, which create
lower back-pressure at higher rpm,
take considerably longer to spin
up under power due to the large
cross-sectional area and relative
inertia of the heavier turbine.
Generally, this type of turbo will
only be effective in the medium
rpm range. This phenomenon,
Turbocharger guide vane adjuster Turbocharger with Variable Turbine Geometry (VTG)
up easily to its optimum speed.
The key disadvantage of using
a smaller turbo is that the back-
pressure generated at higher
engine speeds causes a significant
reduction in performance.
Resistance is caused by the smaller
cross-sectional area through which
the exhaust is required to flow.
The 911 Turbo has always been
synonymous with performance.
Now the car is more capable than
ever thanks to a new twin turbo
system featuring Variable Turbine
Geometry (VTG).
On a conventional turbocharger,
the exhaust flow drives a turbine
that is connected to a compressor
in the air intake tract. By ‘squeezing’
the incoming air, the amount
of oxygen in a given volume isincreased. Since compression also
causes an increase in temperature,
the air must be passed through
an ‘intercooler’ unit. With more
oxygen present in each cylinder
charge, more fuel can be burnt
yielding greater energy. Since
higher exhaust pressures generate
corresponding loads on the intake
side, the intake pressure must
be carefully controlled in order
to protect the engine. On the new
911 Turbo, the ‘boost pressure’ islimited using ‘wastegate’ valves
that bypass excess pressure
around the twin exhaust turbines.
Another important factor is the
size of the turbo unit. Since a
smaller turbine has a lower mass,
it generally responds more quickly
to increasing pressure, spinning
the turbines via electronically
adjustable guide vanes. By
changing the vane angle, the
system can replicate the
geometry in all types of turbo,
large or small.
With Variable Turbine Geometry
(VTG), it is possible to achieve
higher turbine speeds, and thus
higher boost pressure, at lower
engine rpm. Cylinder charging issignificantly improved, with a
corresponding increase in both
power and torque. Maximum
torque is reached at lower rpm
and is retained across a wider rev
range. A full 620 Nm is available
from as low as 1,950 rpm up to
5,000 rpm. Every throttle input is
met with exceptional response
and phenomenal acceleration.
When the boost pressure reaches
its maximum value, the guide

The rear axle assembly is a race-
proven design featuring multi-link
LSA (Lightweight, Stable, Agile)
subframe-based suspension. Its
lightened construction provides
exceptional dynamic properties.
The axle kinematics improve
stability under acceleration by
reducing excessive compression.
The lightweight strut has an
aluminium damper instead of
conventional steel to help improve
handling and agility.
Combined, the suspension enables
smooth high-speed manoeuvres
in all road and track scenarios.
Pitch and roll are reduced to a
· 53 ·The new 911 Turbo |
Chassis
To transmit power with optimum
efficiency, the front and rear
suspension must be a s stable,
and as light, as possible.
Reducing weight, particularly on
the unsprung masses, brings
major benefits in terms of driving
dynamics.The new 911 Turbo is equipped
with an electronic damping
system as standard. For more
information on Porsche Active
Suspension Management (PASM),
see page 56.The independent front suspension
combines McPherson-type struts
with longitudinal and transverse
links. Each front wheel is preciselylocated, ensuring excellent
handling and directiona l stability.
Brake spoiler elements provide
efficient cooling for each of the
front brake units.
· 52 ·Front axle 911 TurboRear axle 911 Turbo
Suspension.
Precision, strength and lightweight design.
minimum, as are tyre noise and
vibration. Overall, the car offers
a level of stability that is equal to
the car’s performance potential.

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

· 126 ·· 127 ·
Technical data911 Turbo
WeightsManual/ Tiptronic S
Unladen weight (DIN)1,585 kg/1,620 kg
Unladen weight (EC)*1,660 kg/1,695 kg
Permissible gross weight1,950 kg/1,980 kg
PerformanceManual/ Tiptronic S
Top speed310 km / h/310 km / h (193 mph/193 mph)
0 –100 km / h (0 – 62 mph)3.9 secs/3.7 secs
0 –160 km / h (0 – 99 mph)8.4 secs/7.8 secs
0 – 200 km / h (0 –124 mph)12.8 secs/12.2 secs
Flexibility 80 –120 km / h 3.8 secs/3.5 secs
(50 –75 mph) in second highest gear
Fuel consumption/emissionsManual/ Tiptronic S
In accordance with 80 / 1268 /EC as valid at time of going to press**
Urban18.8/19.8 l/100 km (15.0/14.3 mpg)
Extra urban9.5/9.6 l/100 km (29.7/29.4 mpg)
Combined12.8/13.6 l/100 km (22.1/20.8 mpg)
CO2emissions307/326 g/km
Dimensions /aerodynamics
Length4,450 mm
Width1,852 mm
Height1,300 mm
Wheelbase2,350 mm
Luggage compartment volume105 litres
Tank capacity 67 litres
(refill volume)
Drag coefficient
0.31
911 Turbo
Engine
Cylinders6
Displacement3,600 cm3
Max. power (DIN)353 kW (480 bhp)
at6,000 rpm
Max. torque620 Nm (with overboost: 680 Nm)
at1,950 – 5,000 rpm (with overboost: 2,100 – 4,000 rpm)
Compression ratio9.0 :1
Transmission
LayoutAll-wheel drive with electronically controlled multi-plate clutch
Manual gearbox6-speed
Tiptronic S (optional)5-speed
Chassis
Front axleMcPherson-strut suspension
Rear axleLSA multi-link suspension
SteeringVariable steering ratio, power-assisted (hydraulic)
Turning circle10.9 m
Brakes6-piston monobloc aluminium fixed calipers at front, `
4-piston monobloc aluminium fixed calipers at rear,
discs internally vented and cross-drilled
Vehicle stability systemPSM (updated version)
Anti-lock braking systemABS 8.0
WheelsFront: 8.5J x 19 ET 56
Rear: 11J x 19 ET 51
Ty r e sFront: 235/35 ZR 19
Rear: 305/30 ZR 19* Weight is calculated in accordance with the relevant EC Directives and is valid for standard specification vehicles only.
Optional equipment means greater weight. The figure given includes 68 kg for the driver and 7 kg for luggage.
** Provisional data only. Final data unavailable at the time of going to press.