consistently within a specific
temperature range. The engines
in the Cayenne models are
therefore designed for ef ficient
cooling.
In order to reduce the frictional
losses that occur during warm -up,
all Cayenne models feature com-
prehensive thermal management.
Using intelligent control, it
activates the dif ferent cooling
circuits individually and on de-
mand, thereby ensuring that the
optimum operating temperature
for the engine and transmission
is reached more quickly. This
minimises friction – and keeps
fuel consumption and CO
2 emis-
sions low.
The V8 engines have an enhanced
coolant management system
offering effective temperature
control throughout the engine.
While 20 % of coolant flows longi-
tudinally through the crankcase,
the remaining 80 % serves the
cylinder heads using the proven
cross-flow principle (from hot to
cold).
On all Cayenne models, the piston
heads are cooled using oil-spray
jets integrated within the main
lubrication system.
The entire cooling system is
designed for prolonged heav y-
dut y use, e.g. of f-road driving
or heav y towing and carrying
applications.Lubrication.
The V8 engines use dry-sump
lubrication to ensure a consistent
supply of oil in all load conditions,
especially in of f-road terrain.
The oil reservoir is located inside
the engine. This saves on space
and reduces weight.
Oil is circulated around the V8
engines using a demand- driven
pump. This has been designed
for the toughest driving scenarios
on and off road, including per-
formance driving and extreme
gradients. The V6 engines have a wet-sump
lubrication system.
Ensuring a
reliable supply of oil, no mat ter
how challenging the driving
conditions.
Direct fuel injection on the
diesel engine (common-rail
injection system).
On the Cayenne Diesel, direct
fuel injection comes courtesy of
a common -rail injection system.
The injection pressure is now up
to 2,000 bar, ensuring optimum
distribution of the air/fuel mixture
– for greater performance. The
piezoelectric injectors provide
flexible injection rate
adjustment,
using exactly metered quantities
of fuel, with multiple injections
for each power stroke to deliver
smooth combustion.
Cooling systems.
A high -performance engine can
only maintain its maximum
capabilit y over a long service life
if all components are operating
Direct fuel injection (DFI).
DFI injects fuel directly into the
combustion chamber at up to
120 bar with millisecond precision
using electromagnetic injectors.
The injector position and spray
geometry have been carefully
designed to improve output,
torque, fuel economy and emis-
sions. The swirling of the fuel as
it enters each chamber increases
the mixing of air and fuel, thereby
enhancing combustion. By form-
ing the air/fuel mixture directly
in the combustion chamber, DFI
contributes to engine cooling.
As a result, it was possible to in-
crease the compression ratio and
therefore power and efficiency.
Compression with precision.
Essential for getting right to the point.
38 · Drive systems and chassis | Engine technology
