Audi 4.2-litre V8 FSI, Service Training

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Intake system in the Audi RS4
The intake system of the RS4 engine was designed
with emphasis on maximum flow control. Pressure
loss is minimised by a large cross-sectional areas in
the hot-film air mass meter (HFM) and air intake
pipe in combination with a 90 mm diameter throttle
valve.
To ensure a sufficient supply of air to the engine at
high RPM, the power flap in the air filter is opened
at engine speeds higher than 5000 RPM and at road
speeds higher than 200 kph.
The power flap is opened and closed by a vacuum
actuator which is map-controlled by the engine
control unit via the variable intake manifold change-
over valve N335.
The sand cast aluminium intake manifold was
designed specially to match the sporty characteris-
tic of the engine. In contrast to the basic engine,
maximum torque is produced at higher engine RPM.
At this engine speed, the intake manifold change-
over valve would be switched to the short path for
higher power output.
The RS4 engine does not have a variable inlet manifold.
Throttle valve module
Intake manifold
Hot-film air mass meter (HFM5)
Air intake
Air intake
Air intake
Power flap
Air intake pipe
Vacuum unit
for power flap
Cylinder head
Intake manifold flaps