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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.
