BMW 5 - Manual (Page 30)

BMW
Media
Information
11/2009
Page 30
The petrol engines in the new BMW 5 Series:
a perfect combination of innovations for supreme efficiency.
Offering the spontaneity, fast-revving performance and refinement so
typical of the brand, combined with unparalleled efficiency, the petrol
engines featured in the new BMW 5 Series Sedan come with a standard
quite unparalleled in the market. Both the eight-cylinder power unit in
the top-of-the-range BMW 550i and the three straight-six engines come
with outstanding technical innovations created in the context of
BMW EfficientDynamics. And the specific combination of technologies
gives each of the four drive units its own quite unique characteristics.
The most important feature shared by all petrol engines is fuel supply by
means of second-generation direct fuel injection. Already well-known as
High Precision Injection, this advanced system uses injectors positioned
in the middle between the valves and in the immediate vicinity of the spark
plug for the precise dosage of fuel, measurably reducing fuel consumption
also in everyday traffic.
A particularly efficient version of High Precision Injection is to be admired in
the six-cylinder engines driving the new BMW 528i and the new BMW 523i.
Direct injection in the lean-burn mode gives these models particularly good
fuel economy. Referred to as stratified charging, this process forms various
interacting layers of different fuel/air mixtures within the combustion chamber,
the share of petrol in the mixture decreasing continuously with an increasing
distance from the spark plug. A particularly rich and therefore ignitable fuel/air
mixture is therefore available only in the direct vicinity of the spark plug.
As soon as this mixture is ignited, the leaner layers at a greater distance from
the spark plug will also burn in a clean and consistent process.
In the V8 power unit of the new BMW 550i and in the straight-six engine
featured in the new BMW 535i High Precision Injection is combined with
turbocharging. BMW TwinPower Turbo Technology provides power and
performance characteristics a naturally-aspirated engine would only be able
to offer on much larger capacity, making it heavier and obviously consuming
more fuel and generating more emissions.
The eight-cylinder with BMW TwinPower Turbo and High Precision Injection
is the only petrol engine of its kind with a turbocharger and catalysts arranged
within the V-section between the two rows of cylinders, and at the same time
it is the world’s most efficient power unit in its performance class. Compared
with its predecessor, the new BMW 550i offers 30 kW more power on
approximately 5 per cent less fuel.