light BMW 645Ci COUPE 2002 E63 N62B44 Engine Workshop Manual

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N62 Engine
N62 Engine
Purpose of The System
The N62B44 engine is a completely new development from the NG (New Generation) series
and is available as a B44 (4.4 liter).
The development objectives were:
• Reduction in fuel consumption
• Reduction in emissions
• Increased power
• Improved torque and torque curve
• Improved engine acoustics
The most important features of
the new N62 engine are:
• 8 cylinders in a 90º V configu-
ration
• 2 four-valve cylinder heads
• Light-alloy design
• Newly-developed variable
intake manifold
• Valvetronic system
In conjunction with the Variable Intake Manifold, the Valvetronic system adapts the intake
valve lift to ensure optimum cylinder filling. The throttle valve use is limited during engine
operation to maintain a constant intake manifold vacuum.
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To achieve these objectives, enhancements
were made in the following areas:
• Engine mechanicals
• Treatment of exhaust emissions
• Valve timing
• Engine management control
• Intake air flow
43-02-01

Downloaded from www.Manualslib.com manuals search engine Exhaust System
The exhaust system is completely redesigned for the N62B44 engine. It has been opti-
mized in terms of cylinder filling, scavenging, sound level and rapid catalytic converter light-
off.
Exhaust Manifold with Catalytic Converter
Each cylinder bank is equipped with a four into two into one exhaust manifold. The mani-
fold and the catalytic converter housing together form one component. A ceramic-bed pre-
catalytic converter and a ceramic-bed main catalytic converter are arranged one behind the
other in the catalytic converter housing.
The mounting for the broadband planar oxygen sensors (Bosch LSU) and the secondary
oxygen sensors is located in front of and behind the catalytic converter.
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N62 Engine
42-02-13 Exhaust System
1. Manifold with Integrated Catalytic Converter
2. Broadband Planar Oxygen Sensors
3. Secondary Oxygen Sensors
4. Exhaust Pipe with Front Silencer
5. Center Silencer
6. Exhaust Gas Flap
7. Rear Silencers

Downloaded from www.Manualslib.com manuals search engine Valvetronic
Over the entire speed and load range, the gasoline engine needs a combustible fuel-air
mixture within the ideal ratio (Lambda = 1). The mixture quantity must be altered to vary the
speed and output. This variation is effected by the throttle valve. The mixture, which falls
within the narrow range of Lambda = 1, is formed outside the combustion chamber using
the fuel injection system (external mixture formation).
The mixture control is influenced by the throttle valve and is not optimal in all the different
load ranges. This is particularly true in the idle to part-load ranges, since the throttle valve
is only opened slightly in these ranges. The consequences are less than optimal cylinder
filling, torque and increased fuel consumption.
Technical measures were previously introduced; such as the optimization of air/fuel mixing,
improved valve overlap, introduction of DISA and the steady improvement of mixture con-
trol all depend on the throttle valve. This is where the new completely unique Valvetronic
design comes in.
The Valvetronic system simultaneously varies the valve opening time and the valve opening
lift between 0.3 mm and 9.85 mm, according to engine speed and load. This means that
the air/fuel mixture volume is controlled according to engine requirements. This type of mix-
ture and volume control makes the typical throttle valve control unnecessary.
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N62 Engine

Downloaded from www.Manualslib.com manuals search engine Physical considerations:
On engines with throttle valve control, the throttle valve is slightly open in the idling and part-
load ranges. This results in the formation of up to 500 mbar vacuum in the intake manifold,
which prevents the engine from aspirating freely and in turn prevents optimum cylinder fill-
ing. The Valvetronic system with an open throttle valve largely counteracts this disadvan-
tage. The air-mass flow to the intake valves is unrestricted. The full ambient pressure is
available directly at the intake valves for cylinder filling and scavenging.
The Valvetronic system primarily controls the fill by adapting the valve opening time and the
valve lift (short opening time/small valve lift = lower fill, and vice versa). During the valve
opening phase the engine aspirates more freely via the intake valves even with small valve
lifts vs. a throttle valve which is continuously blocked.
The slower cylinder filling from the intake valves with partial lift results in more turbulence in
the combustion chamber, thus faster and better mixture control and more efficient com-
bustion. At lower engine speeds this effect is intensified by opening the intake valves later,
after top dead center (ATDC) using VANOS. This increases vacuum in the combustion
chamber which accelerates filling and turbulence when the intake valves are opened.
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the additional variability of the Valvetronic system results in optimization of
cylinder filling and scavenging throughout the engine's entire operating range. This has a
positive effect on output, torque and a decrease in fuel consumption and exhaust emis-
sions.
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• Valve lift adjustment
• VANOS for intake and outlet
• Variable intake manifold
• Mixture control and ignition control
• Other individual engine design measures
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• Improved engine idling
• Improved engine torque
• Improved engine torque curve
• Fewer pollutant emissions
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N62 Engine
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• Improved cylinder filling with air/fuel mix-
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• Improved mixture control before the cylin-
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• Improved combustion procedure

Downloaded from www.Manualslib.com manuals search engine 47
N62 Engine
Flywheel
The lightweight flywheel is made from a laminated plate. The
starter ring gear is also the increment wheel for engine speed
and crankshaft positioning/misfire detection.
The ring gear is riveted directly to the flexplate (6). The fly-
wheel diameter is 320 mm.
Vibration Damper
The vibration damper is a torsional vibration absorber (axial
design). The outer edge of the damper has a notch (1) to
accept the locating tool when positioning the crankshaft for
initial setting.
The locating tool inserts into the raised mount in the front
cover (2). R Re
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Engine Mounting
The engine is secured by two hydraulic damping mounts that are located on the front axle
carrier (structure and function are the same as the E38/M62).
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