Porsche 911 GT2 Brochure page 14

To overcome this problem, the With 680 Nm available between
twin water-cooled turbochargers 2,200 and 4,500 rpm, the
on the 911 GT2 feature Variable resulting acceleration is nothing
Turbine Geometry (VTG). With less than phenomenal.
this technology, the gas-flow
from the engine is channelled When the boost pressure reaches
onto the turbines via electronically its maximum value, the guide
adjustable guide vanes. By chang- vanes are opened further. By
ing the vane angle, the system varying the vane angle, it is
can replicate the geometry in all possible to generate the required
types of turbo, large or small, boost pressure at all engine
and thus achieve the optimum speeds. As a result, there is no
gas-flow characteristics. The guide need for excess pressure valves
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.
on the intake side as found
on conventional turbocharged
engines.
This delivers impressive
engine efficiency and lower
fuel consumption.
Guide vanes closed Guide vanes closed
Guide vanes open Guide vanes open
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The 911 GT2 |
Turbocharger guide vane adjuster
1
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
Drive