charging PORSCHE 911 GT2 2008 5.G Information Manual

· 13 · · 12 ·
The 911 GT2 |The 911 GT2
Always composed. Even in extremes.
Engineering the 911 GT2.
How do we know our limits?
Because we choose to
explore them.
The 911 GT2.The Porsche 911 GT2. The excep-
tion to the rule. Every new edition
has clearly exceeded everything
that has gone before. Designing a
911 GT2 requires a new approach
to old ideas. It means questioning
convention, crossing the limits,
thinking beyond the norm. It
means not being confined to
torque of 680 Nm is available
from 2,200 to 4,500 rpm. At
5,500 rpm, it is still higher than
650 Nm. The benchmark sprint
to 100 km / h (62 mph) is com-
pleted in 3.7 seconds. Maximum
speed is 329 km / h (204 mph).
For some, that number means
little on paper – but it all becomes
clear on the road. With a driving
experience – and an engine sound
– that can only be conceived in
the Porsche 911 GT2. Performanceand efficiency have both been
improved, mainly through changes
to the turbocharging system. The
flow-optimised turbines and com-
pressor units have been specially
adapted to the engine output and
offer a more effective turbochar-
ging process.
In addition, an expansion intake
system has been specially devel-
oped for the 911 GT2 (see page
32) which overturns all previous
principles of air supply to turbo road or track, straight or bend,
comfort or sports performance.
It means having the freedom to
leave what you know and examine
new possibilities. The result: our
most powerful road-going 911.
The source of that power is a
3.6-litre flat-six boxer enginebased on the current 911 Turbo.
Special features include VarioCam
Plus and twin turbochargers with
Variable Turbine Geometry (VTG,
see page 28) enabling faster
response at lower engine speeds.
Together, they generate even
greater power: a mighty 390 kW
(530 hp) at 6,500 rpm. Maximumengines. Equally effective is the
new rear silencer, now made from
ultra-lightweight titanium.
In the end, even we were impressed
with the power of the 911 GT2, as
we had not expected that so much
potential existed in the engine of
the 911 Turbo from which it is
derived. This was achieved because,
in terms of development, we
were prepared to go down new,
previously unexplored avenues.

· 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.

· 25 · · 24 ·
The 911 GT2 |Drive
Lightweight design.
The six-cylinder twin-turbo boxer
engine is a compact unit offering
excellent cylinder charging and
torque-curve characteristics
as well as first-rate balance with
minimal vibration. The flat-six
design allows a low centre of
gravity with resulting advantages
for traction and driving dynamics.
The alloy crankcase consists of
two main sections, each contain-
ing one bank of cylinders. Thecrankshaft runs in eight main
bearings and is driven by forged
connecting rods. For optimum
strength and durability, we’ve used
forged aluminium pistons running
in Nikasil-coated aluminium liners
and cooled via individual oil-spray
jets. The results: lower frictional
resistance and a lengthy service
life – even when subjected to
heavy use.
The cylinder heads are made
from an extremely heat-resistantlightweight alloy. Each cylinder
bank has two overhead camshafts
driving a set of four valves (two
inlet and two exhaust) on each
individual cylinder. The valves are
arranged in a ‘V’ formation and
have a highly efficient dual-spring
closing action enabling higher
engine speeds. Performance is
enhanced with the aid of both
Variable Turbine Geometry (VTG,
see page 28) and VarioCam Plus
(variable valve timing and lift on
the inlet side). The benefits are
not only greater power and
torque, but also better fuel
econ-
omy and lower emissions.
Dry-sump lubrication.
This racing technology uses a
separate oil reservoir to ensure
consistent oil pressures through-
out the engine, even during pro-
longed periods of lateral and longi-
tudinal loads. After passing
through the engine, every drop of oil is returned directly to the
external reservoir. The flow is dri-
ven by two scavenge pumps in
each cylinder head and a further
two pumps in the crankcase. Gas
is removed from the returning
oil via a defoaming device in the
reservoir. The oil is returned
to the lubrication points in the
engine by means of a dedicated
oil-feed pump. With a further
scavenge pump in each of the
twin turbocharger units, the
911 GT2 has a total of nineseparate pumps driving the lubri-
cation system. The oil level can be
checked from inside the car via
the standard on-board computer.
The 911 GT2 is factory-filled with
Mobil 1 high-performance fully
synthetic oil. The exceptional
properties of this premium-quality
lubricant ensure reliable starting
even in the coldest conditions. It
also reduces wear and contributes
to the long-term durability of the
engine.

· 29 · · 28 ·
The 911 GT2 |Drive
turbine has a lower mass, it
responds more quickly to increas-
ing pressure, spinning 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.
On a conventional turbocharger,
the exhaust flow drives a turbine
that is connected to a compressor
on the intake side. By compressing
the incoming air, the amount
of oxygen in a given volume is
increased. Since compression also causes an increase in
temperature, the air must be
cooled in a device known as an
‘intercooler’. With more oxygen
present in each cylinder charge,
more fuel can be burnt, yielding
greater energy. Since higherexhaust pressures generate
greater loads on the intake side,
the intake pressure must be
carefully controlled in order to
protect the engine. This ‘boost
pressure’ is limited using ‘waste-
gate’ valves that bypass excess
pressure around the turbine.
Another important factor in
the system is the size of the
turbocharger. Since a smaller Porsche has a long and celebrated
tradition of using turbocharged
power on both road and track.
On the 911 GT2, we’ve
enhanced
this technology with Variable Turbine
Geometry (VTG).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,
known as ‘turbo lag’, means there
is virtually no turbocharging
effect at lower engine speeds.
Turbocharger with Variable Turbine Geometry (VTG)
Breathe easy – when holding your breath.
Variable Turbine Geometry (VTG).