Porsche 911 GT2 Brochure page 12

Engine cooling. VarioCam Plus.
The engine of the 911 GT2 features VarioCam Plus is a variable valve
cross-flow water cooling with fully timing system on the inlet side
integrated coolant management. which also features two-stage valve
This technology ensures a consis- lift. The benefits it provides include
tent flow of coolant to each of greater power and torque at all
the engine's cylinders. Waste engine speeds, as well as excellent
heat from the oil is transferred to running characteristics, better fuel
the coolant via two oil/water heat economy and fewer emissions.
exchangers. The coolant is routed
through twin radiator modules Essentially, VarioCam Plus makes
ahead of the front wheels and a two engines out of one. The first is
centrally placed unit in the nose. geared for normal road driving, the
second for high-performance use.
The system switches seamlessly
between the two as the driver
inputs change. All operations
are controlled by the engine
management system. The results:
emphatic acceleration and
smoother running.
The two-stage lift mechanism
on each inlet valve consists of an
electro-hydraulically switchable
tappet. Each of the 12 tappets con-
sists of two concentric parts – an
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outer ring and a central shaft –
which can be locked together by
means of a pin. The system can
then vary the valve lift by using
two large profile cams on the outer
ring or a smaller cam lobe on the
central shaft. The timing of each
valve is steplessly controlled by
means of an electro-hydraulic
rotary vane adjuster at the head
of the corresponding camshaft.
To improve responsiveness during
warm-up in cold weather, VarioCam
Plus will select the higher valve
lift setting and retard valve timing.
At medium revs and low engine
loads, the lower valve lift setting This results in copious torque
is activated and timing advanced in and exceptional fuel economy,
order to reduce fuel consumption particularly in comparison with
and emissions. The economy of much larger engines offering
the engine is particularly enhanced similar power output.
at lower engine speeds. For maxi-
mum power and torque, the higher
lift setting is selected and the tim-
ing of the valves is advanced.
The 911 GT2 |
VarioCam Plus
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Drive