low oil pressure PORSCHE 911 GT2 2008 5.G Information Manual

· 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.

· 20 ·· 21 ·The 911 GT2 |
Drive
At Porsche, our aim is not to
increase power – except through
increased efficiency. Which is
why we began with the 911 Turbo
when developing an engine for
the 911 GT2. Its power is com-
bined with rear-wheel drive for
racing-car driving dynamics. But
how is it possible to improve onan engine that is already so close
to perfection? How did we introduce
even greater potential – and the
character of a racing engine? The
answer: by increasing efficiency.
This was mainly achieved by four
crucial components, one of these
being the six-cylinder twin-turboboxer unit with flow-optimised
turbines featuring Variable Turbine
Geometry (VTG, see page 28)
and larger compressors on the
intake side. Together with
VarioCam Plus (see page 26), they
boost performance while reducing
emissions over the entire engine
speed range. Also with the innovative expansion intake system
which works on highly efficient
principles that are contrary to all
previous methods (see page 32).
In addition, the new lightweight
rear silencer made from titanium
enhances performance by producing
less back-pressure through the
exhaust system.
Oil is evenly distributed under all
load conditions (e.g., high-speed
cornering) thanks to a dry-sump
lubrication system with external
tank. After passing through the
engine, the oil is cooled by means
of a dedicated oil-water heat
exchanger. Both of these systems
are proven in competition use.
The water-cooled flat-six twin-turbo
engine with four-valve technology
in the rear of the 911 GT2
generates a mighty 390 kW
(530 hp) from a 3.6-litre
displacement at 6,500 rpm.
Maximum torque of 680 Nm is
achieved at low rpm and sustained
across much of the engine
speed range. It is available
between 2,200 and 4,500 rpm
and the resulting acceleration is
quite literally breathtaking.
300 500 550
600
650
700 750 800
850
280 300 320 340 360
380
400
2000 3000 4000 5000 6000 7000
350 400
450
1000
Power (kW)
Engine Speed (rpm)
180 200 220 240 260 420
900
Torque (Nm)
390 kW (530 hp)
680 Nm
The benchmark sprint to 100 km/ h
(62 mph) is completed in
3.7 seconds; 200 km / h (124 mph)
requires just 11.2 seconds.
Maximum speed – if you really
want to put it to the test – is
329 km / h (204 mph). Even more
impressive is the power-to-weight
ratio of 361 hp per tonne and
the specific power output of
147 hp per litre. Fuel economy
is also exceptional for a car
with such high performance.
There is nothing ordinary about
the 911 GT2 and it exceeds even
the highest expectations. In
other words: everything you’d
expect from the most powerful
road-going 911.
911 GT2 : 680 Nm from 2,200 to 4,500 rpm, 390 kW (530 hp) at 6,500 rpm 3.6-litre twin-turbo boxer engine
The greatest strength comes from within.
Engine.

· 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.

· 31 · · 30 ·
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The 911 GT2 |Drive
1. Turbine casing
2. Movable guide vanes
3. Turbine wheel
4. Electric motor for guide
vane adjustment
5. Guide vane adjuster
6. Compressor casing
7. Compressor wheel
8. Recirculation valve
9. Oil inlet
10. Coolant inlet
Guide vanes open Guide vanes closed
Guide vanes open Guide vanes closedTurbocharger guide vane adjuster
To overcome this problem, the
twin water-cooled turbochargers
on the 911 GT2 feature Variable
Turbine Geometry (VTG). With
this technology, the gas-flow
from the engine is channelled
onto the turbines via electronically
adjustable guide vanes. By chang-
ing the vane angle, the system
can replicate the geometry in all
types of turbo, large or small,
and thus achieve the optimum
gas-flow characteristics. The guide
vanes are controlled by the engine
management system. The result
is a high turbine speed – and
therefore higher boost pressure –
even at low engine rpm. With
more air available, the combustion
is increased, yielding greater
power and torque.
Special features on the 911 GT2
include flow-optimised turbines
and larger compressors which
generate a higher boost pressure.
Maximum torque is
achieved at
low rpm and sustained across
much of the engine speed
range.With 680 Nm available between
2,200 and 4,500 rpm, the
resulting acceleration is nothing
less than phenomenal.
When the boost pressure reaches
its maximum value, the guide
vanes are opened further. By
varying the vane angle, it is
possible to generate the required
boost pressure at all engine
speeds. As a result, there is no
need for excess pres
sure valveson the intake side as found
on
conventional turbocharged
engines.
This delivers impressive
engine efficiency and lower
fuel consumption.

· 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.