Downloaded from www.Manualslib.com manuals search engine Engine Covers
Each cylinder head has a plastic cover for the ignition coil cabling and top of the cylinder
head. The covers “push fit” into rubber grommets on the cylinder head covers.
A sound absorption cover for the top of the
engine also covers the two Valvetronic motors.
This cover is fixed to the intake manifold hous-
ing using four bolts.
The cylinder head covers are made from plastic. The retaining sleeves for the ignition coils
have molded-on gaskets. The sleeves must be replaced if any hardening or damage is vis-
ible on the gaskets. The sleeves are inserted into the cylinder head through the cylinder
head cover (nos. 1through 4).
N No
ot
te
es
s:
:
21
N62 Engine
42-02-21
Engine Covers
Cylinder Head Cover
1. Cylinder Head Top Cover
2. Sound Absorption Engine Cover
1-4. Opening for Spark Plugs
5. Pressure Control Valve
6. Opening for Valvetronic Motor
7. Opening for Valvetronic Sensor Connector
8. Camshaft Sensors (Intake and Exhaust)
43-02-12
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.
I In
n
s
su
um
mm
ma
ar
ry
y,
,
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.
F Fe
ea
at
tu
ur
re
es
s:
:
• Valve lift adjustment
• VANOS for intake and outlet
• Variable intake manifold
• Mixture control and ignition control
• Other individual engine design measures
T Th
hi
is
s
r
re
es
su
ul
lt
ts
s
i
in
n:
:
• Improved engine idling
• Improved engine torque
• Improved engine torque curve
• Fewer pollutant emissions
T Th
he
es
se
e
b
be
en
ne
ef
fi
it
ts
s
r
re
es
su
ul
lt
t
i
in
n
a
a
c
cl
le
ea
ar
r
i
im
mp
pr
ro
ov
ve
em
me
en
nt
t
i
in
n
p
pe
er
rf
fo
or
rm
ma
an
nc
ce
e
a
an
nd
d
f
fu
ue
el
l
c
co
on
ns
su
um
mp
pt
ti
io
on
n
r
re
ed
du
uc
c-
-
t ti
io
on
n
(
(1
14
4%
%)
)
f
fo
or
r
t
th
he
e
d
dr
ri
iv
ve
er
r.
.
24
N62 Engine
T Th
he
e
m
ma
ai
in
n
b
be
en
ne
ef
fi
it
ts
s
o
of
f
t
th
he
es
se
e
f
fe
ea
at
tu
ur
re
es
s
a
ar
re
e:
:
• Improved cylinder filling with air/fuel mix-
ture
• Improved mixture control before the cylin-
der inlet
• Improved combustion procedure
