TURBOCHARGER AND APC
SYSTEM
Turbo
models
are equipped
with
a
turbocharger
and
Automatic
Perfo
rmance
Control
(APC) Sys-
tem.
Turbocharger
The
turbocharger
is
an
exhaust
driven compre..s,
sor
that
increases
the
flow
and pressure
of
the
air
entering
the
cylinders.
This
allows
induction
and
burning
of
a larger fuel charge thereby in·
creasing power
output
over
that
of
a conven-
tional
engine.
Being driven by
the
flow
of
exhaust
gases, the
speed
of
the
turbocharger
and, therefore, the
charging
pressure,
are
pr
o
portional
to
the
speed and load
of
the
engine
. A charge pressure
regulator
(wastegate)
which
is regulated by
an
electrically
modulated
pressure
signal
from the
APC system,
controls
the
flow
of
exhaust
gases
to
the turbine.
Turbocharged
engines
are equipped
with
an
engine
011
cooler
that
is
located
at the lower
left
of
the radiator. The
impeller
shaft
bearing ac·
tually
floats
on a
thin
film
of
engine
oil
circu
·
lated
through
the
turbocharger
housing by the
engine
oil
pump.
Maintaining
a clean
oil
supply
is therefore
Important
to
the service
life
of
the
unit.
APe System
The APC System
consists
of
simple
electr
o
nic
components
that
make it
durable
and easy
to
service. A
knock
detector
(1)
on the engine
block
senses the
onset
and degree
of
engine
knock
and
transmits
an
electronic
signal to the con-
trol
unit
(3)
which
also
receives a signal from the
inlet
manifold
pressure
transducer
(2
) and from
the
ignition
system
(engine rpm). The data is
processed by
the
control
unit
(3)
which
trans-
mits
a
signa
l
to
a
solenoid
valve
(4)
that
modu-
lates the
control
pressure
to
the
charge pres·
sure regulator (wastegate) actuator.
The APC
System
control
unit
has been op-
timized
with
a fixed
sensitivity
and pre-set high
charge pressure
limit
to
prote
ct the engine.
3
1 APC Knock Detector
2.
APC Pressure Transducer
3.
APC Electrical Control Unit
4.
APC Solenoid Valve
5.
RPM
Signal From
Ignition
System
6.
Turbocharger
Maximum
operating
charge pressure under
lull
load is
electronically
governed. The
wastegate
is
mechanically
apjusted
to
provide
a safe, low
charge pressure
limit
should
the
APC System
cease
to
function.
7.
Wastegate (Charge Pressure Regulator)
8. Wastegate
Actuator
9.
Overpressure safety
switch
10. Inlet Air
Flow
(From CIS Metering Unit)
11
. Exhaust (to Catalytic Converter)
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