· 34 ·· 35 ·
The 911 GT2 |Drive
Exhaust system.
The rear silencer and tailpipes
of the 911 GT2 are made from
ultra-lightweight titanium to re-
duce the weight on the rear axle,
and improve driving dynamics.
The exhaust leaves the engine
through high-performance
manifolds into separate tracts
for each of the two banks of
cylinders. Twin three-way catalytic
converters clean the two streams
before they converge in the main
silencer unit. The twin
titaniumtailpipes are fully integrated
within
the rear apron moulding. Large-
diameter tubes reduce back-
pressure
on the engine,thereby
increasing performance. The
catalytic
converters are close
to the engine,
enabling faster
warm-up and therefore improving
efficiency. When starting from
cold, the process is assisted by a
secondary air injection system.
A system of ‘Lambda’ or oxygen
sensors in each of the exhausts
provides continuous monitoring of engine efficiency. Data supplied
by one pair of sensors enables
the engine management system
to perform separate adjustment
of the air/fuel mix for each bank
of cylinders. A further pair of sen-
sors*, one on each tract, is used
to monitor the efficiency of the
respective catalytic converter. This
facility enables much more accu-
rate control of potentially harmful
emissions.
The exhaust system on the
911 GT2 produces a warm,
deep and bass-rich sound –
even when the engine is idling.
Fuel system.
Fuel is supplied to each of the six
cylinders using a sequential fuel
injection system. The timing of
each injection and the volume
supplied to each bank of cylinders
are controlled by the engine
management system. Adjustmentsare based on a range of variables,
including throttle position, engine
speed, boost pressure, coolant
temperature and exhaust gas com-
position. The results are optimised
combustion and fuel consumption.
A hot-film air mass sensor moni-
tors the volume and density of the
incoming air to ensure the best
possible air/fuel mix, regardless
of weather and altitude.
Ignition system.
The 911 GT2 features static
high-voltage ignition technology.
Separate coils on each of the
plugs with platinum electrodes
ensure perfect ignition every
time. The role of distributor is
performed by the engine manage-
ment system, which controls the
individual spark plugs directly,
for optimum performance and
minimum fuel consumption.
* Not in markets with leaded fuel.Exhaust system
· 37 · · 36 ·
The 911 GT2 |Drive
benefits, such as optimum econ-
omy, emissions and performance
in all driving scenarios.
One of the most important tasks
performed by the engine manage-
ment system is cylinder-specific
knock control. By preventing pre-
ignition at high engine speeds
and loads, this function can avert
costly damage to the pistons and
cylinders. Since temperatures
tend to vary across the engine,
each cylinder is monitoredseparately. If a risk is detected,
the individual ignition timing is
adjusted.
The on-board diagnostics system,
designed to European standard,
quickly detects any faults in the
exhaust and fuel system and
displays them during driving
via the car’s instruments. The
benefits include active prevention
of harmful emissions as well
as consistent rates of fuel con-
sumption.Input data Used to regulate /control
Digital engine electronics
(ME7.8.1 control unit)
Engine load
Pressure upstream from throttle
Throttle-valve angle
Engine speed (from crankshaft)
Inlet camshaft phase angle
Throttle-pedal position
Oxygen sensor signals
Knock sensor signals
Ignition
Fuel injection
Throttle valve
Heating elements in oxygen sensors
Fuel pump
Fuel-tank venting
CAN interface to transmissionMoment interface to Porsche
Stability Management (PSM)
VarioCam Plus
– camshaft phase angle
– valve lift control
Electronic controller for
Variable Turbine Geometry (VTG)
Recirculation valve
Secondary air injection
Engine-bay fan
Starter
On-board diagnostics
Air-conditioning compressor
Interface to instrument cluster
Radiator fans (front control unit via CAN)
Vehicle speed
Air-conditioning settings
Engine immobiliser status
Clutch pedal switch
Ambient air pressure
Temperatures
– coolant
– air upstream from throttle
– engine oil
– air in engine compartment
– ambient air
Exhaust-gas temperature
Engine management system.
The Motronic ME7.8.1 engine
management system facilitates
optimum performance at all
times. This high-precision ECU
controls all engine-related func-
tions and assemblies (see
dia-
gram), such as Variable Turbine
Geometry, VarioCam Plus and
the electronic throttle, one of the
key prerequisites for the standard
Porsche Stability Management
(PSM). This produces various
