consistently within a specific
temperature range. The engines
in the new Cayenne models are
therefore designed for optimum
cooling.
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. In addition,
thermal management ensures
that the optimum operating tem
perature for the engines is
reached more quickly. This keeps emissions and fuel consumption
low, even when starting from cold.
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 engine in the Cayenne has
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 of up
to 1,800 bar ensures optimum
distribution of the air/fuel mixture
– for greater performance. The
piezoelectric injection valves
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
