2008 PORSCHE 911 GT2 cooling

· 16 ·· 17 ·
The 911 GT2 |The 911 GT2
being forced into the turbos,
there is less resistance from
the compressors and therefore
less back-pressure in the
exhaust, which means greater
engine performance.
The engine cover, featuring
the GT2 logo, is made from
lightweight glass-fibre reinforced
plastic (GRP). Twin titanium
tailpipes are elegantly incorpor-
ated within the rear apron design.
Warm air is vented from the braking power, with large air
intakes for improved air flow to
the central radiator and front
brakes. The integral air outlet
ahead of the front lid makes a
major contribution to front-enddownforce. The airstream from the
central radiator is channelled up
over the car, forcing the front end
downwards, thereby enhancing
balance and steering response.
The importance of air in the per-
formance of the 911 GT2 is also
apparent from the large intake
openings in the rear side panels
which supply the intercooler units.The most impressive view is also
the one that others will see most
of all: the rear. The fixed rear wing
with integral lip spoiler ensures
optimum stability at speed.
As the car accelerates and you’re
pressed into your seat, air is
forced through the intake openings
on the rear wing uprights and into
the engine turbocharging system.
This ‘ram air’ effect has a key role
to play in the exceptional efficiency
of the engine. Since air is already Power. Torque. Acceleration. All in
plentiful supply. Nothing else can
match that energy – except the
car’s design. A single glance is all
it takes to realise that fact.
The front end is aerodynamically
adapted for the high thermal
load of the engine and increased
Aesthetically. Aerodynamically. Resistance is futile.
Designing the 911 GT2.engine compartment via cooling
slits at the rear.
The combined effect of all these
aerodynamic modifications is a
drag coefficient of just 0.32 as
well as positive front and rear
downforce. Behind the wheel,
that means better grip, better
directional stability and excep-
tional handling characteristics.
Technically and visually, the
result is the same: a breathtaking
driving machine.

· 26 ·· 27 ·
The 911 GT2 |Drive
VarioCam Plus
Engine cooling.
The engine of the 911 GT2 features
cross-flow water cooling with fully
integrated coolant management.
This technology ensures a consis-
tent flow of coolant to each of
the engine’s cylinders. Waste
heat from the oil is transferred to
the coolant via two oil/water heat
exchangers. The coolant is routed
through twin radiator modules
ahead of the front wheels and a
centrally placed unit in the nose.
VarioCam Plus.
VarioCam Plus is a variable valve
timing system on the inlet side
which also features two-stage valve
lift. The benefits it provides include
greater power and torque at all
engine speeds, as well as excellent
running characteristics, better fuel
economy and fewer emissions.
Essentially, VarioCam Plus makes
two engines out of one. The first is
geared for normal road driving, thesecond for high-performance use.
The system switches seamlessly
between the two as the driver
inputs change. All operations
are controlled by the engine
management system. The results:
emphatic acceleration and
smoother running.
The two-stage lift mechanism
on each inlet valve consists of an
electro-hydraulically switchable
tappet. Each of the 12 tappets con-
sists of two concentric parts – anouter ring and a central shaft –
which can be locked together by
means of a pin. The system can
then vary the valve lift by using
two large profile cams on the outer
ring or a smaller cam lobe on the
central shaft. The timing of each
valve is steplessly controlled by
means of an electro-hydraulic
rotary vane adjuster at the head
of the corresponding camshaft.
To improve responsiveness during
warm-up in cold weather, VarioCam
Plus will select the higher valve
lift setting and retard valve timing.
At medium revs and low engine
loads, the lower valve lift setting
is activated and timing advanced in
order to reduce fuel consumption
and emissions. The economy of
the engine is particularly enhanced
at lower engine speeds. For maxi-
mum power and torque, the higher
lift setting is selected and the tim-
ing of the valves is advanced.This results in copious torque
and exceptional fuel economy,
particularly in comparison with
much larger engines offering
similar power output.

· 39 · · 38 ·
The 911 GT2 |Drive
The six-speed manual gearbox in
the 911 GT2 is specifically
designed for the high engine
performance. The individual ratios
are carefully matched to the spe-
cific characteristics of the engine.The gear-lever throw is short and
precise, enabling fast and
accurate gearshifts.
A typical feature of the 911 GT2
is the Launch Assistant – for maximum acceleration from a
standing start. The clutch and
accelerator are depressed when
the vehicle is stationary.
When a
boost pressure of approximately
0.9 bar is displayed in the instru-ment
cluster, release the clutchas
quickly as possible and maximum
a
cceleration automatically ensues.
Normally on a turbocharged vehicle
with manual gearbox, the boost
pressure under acceleration from
a standing start is relatively low.
The turbo effect is delayed as
the engine gathers speed and
the boost pressure starts to build.On the 911 GT2, this initial delay
is reduced. While the car is still
stationary, the fuel injection is
modified to help the engine reach
maximum output earlier. The boost
pressure is significantly increased
and the engine readied for a faster
start.
A specially designed traction
control system adapts the acceler-
ation procedure automatically
in the ECU to ensure optimum
traction. The clutch remains
engaged. This reduces load and
prevents high clutch wear. The
power is transmitted directly to
the road via the rear axle.
The gearbox is combined with
a cable linkage and dual-mass fly-
wheel offering added comfort and
precision. The close ratio spread
enables powerful acceleration
within the optimum engine power
band.
Steel baulk rings on gears two to
five ensure a precise gearshift
action even under extreme loads.Cooling is provided by an add-
itional oil-to-water heat exchanger
and spray lubrication. Both of
these features are essential for
durability in endurance racing
conditions.
Other standard features include
a limited-slip differential with
asymmetrical lock factor. Offering
better traction and handling
when exiting a corner, it applies a
higher proportion of drive torque
to the loaded outer rear wheel.
The term ‘asymmetrical’ means
that one lock factor is applied
when cornering under power
(28 %), and another when braking
for a corner (40 %).
Maximum response to minimum effort.
Transmission.

· 44 ·· 45 ·The 911 GT2 |
Chassis
Rear axle Front axle
The 911 GT2 chassis is designed
for racecar-like performance on
every type of tarmac from motor-
way to track. The car rides about
25 mm lower than the 911 Carrera
and its lightweight build has
reduced overall weight as well as
the unsprung masses. Agile and
responsive, it is stable and secure– particularly during cornering
manoeuvres.
The front suspension with its
special wheel mounts has
McPherson spring struts with
the wheels mounted individually
on trailing arms and wishbones.
Each front wheel is preciselylocated, ensuring excellent
handling and directional stability
in all road and track scenarios.
Brake spoiler elements provide
efficient cooling for each of the
front brake units.The rear axle assembly consists
of subframe-mounted multi-link
suspension featuring LSA con-
struction (Light, Stable, Agile).
This lightened design featuring
an aluminium cross-member
is an important factor in the
exceptional dynamics of the car.
Ride height, camber, toe angle
and anti-roll bar settings can
all be adapted to individual circuit
characteristics, as befits a racing
Porsche.There is virtually no unwanted
movement between the suspen-
sion and body, thanks to special
features such as metal bearings
with ball joints on the front strut
mounts and rigid cross-members
at the rear. This reduced elasticity
and improved wheel location
enable better handling and turn-in.
The 911 GT2 has an electronic
variable damping system as
standard – Porsche Active Suspension Management (PASM,
see page 48).
This variable
damper system offers two basic
setup modes, ‘Normal’ and
‘Sport’.
Racetrack. Motorway. Wherever the road goes.
Chassis.

· 109 · · 108 ·The 911 GT2 |
Index
Index
A
ABS 51
Air conditioning, automatic 69
Airbags 62
Alarm system 75
Anti-theft protection 75
Audio system 76
B
Bi-Xenon lighting system 56
Bodyshell structure 60
BOSE® Surround
Sound System 80
Braking system 58
C
Catalytic converters 34, 85
Charge-air cooling 16
Chassis 42
Chrono Package Plus 75, 92
Clubsport package 64, 92
CO
284
Colours 88
Comfort 66
Communication 76, 96
Cruise control 74
D
Design 16
Drive 18
Dual-mass flywheel 39
E
Electronic logbook 78
Engine 20
Engine cooling 26
Engine management system 36
Environment 82
Exhaust emission control 85
Exhaust system 34
Expansion intake manifold 32
Exterior 91
F
Factory collection 100
Fire extinguisher 64, 93
Front axle 44
Fuel supply 35
Fuel system 35, 85
G
Gearbox, manual 38
GSM telephone module 78
H
HomeLink®74
I
Ignition system 35
Instruments 68
Interior 68, 93
Interior materials 70, 95
K
Knock control,
cylinder-specific 36
L
Launch Assistant 38
Leather 89, 95
Lightweight design 24
Loudspeakers 79, 80
Lubrication, dry-sump 25
Luggage compartment 74
M
Mobile phone preparation 79
N
Navigation module 77
Noise 85
O
Oil supply 25
On-board computer 69
Oxygen-sensor control 34, 85
P
ParkAssist 74, 90
Personalisation 86
Porsche Active Suspension
Management (PASM) 48
Porsche Ceramic Composite
Brake (PCCB) 58
Porsche Communication
Management (PCM) 76
Porsche Side Impact
Protection (POSIP) 62
Porsche Stability
Management (PSM) 50
R
Ram air principle 17
Rear axle 45
Rear wing 17
Recycling 84
Roll cage 64, 92
S
Safety 54
Safety, active 56
Safety, passive 60
Seats 72
Seats, adaptive sports 73, 92
Seats, sport bucket 15, 72
Service 102
Servicing 85
Six-cylinder twin-turbo
boxer engine 20, 24
Sound Package Plus 79
Sport tyres 46
Stability control (SC) 14, 50
Steering 52
Steering wheel 71
Storage compartments 73
T
Technical data 106
Telephone module 78
Traction control (TC) 14, 50
Transmission 38
Turbocharger 28
TV tuner 78
Tyre Pressure
Monitoring (TPM) 47
U
Universal audio interface 79
V
Variable Turbine
Geometry (VTG) 28
VarioCam Plus 26
Vehicle tracking system 75
Voice control system 78
W
‘Welcome Home’ lighting 74
Wheels 46