Audi 2003 A8 Technical Features page 28

Engine, Mechanics
Variable-intake manifold in 3.7 l engine
Vacuum unit
Changeover flap, stage 3
Vacuum unit
Changeover flap, stage 2
This is the same 3-stage variable-intake
manifold as previously fitted in the V8 engine.
Operation of the 3-stage variable-intake
manifold is described in SSP 217.
28
Changeover flap, stage 3
Intake air (inlet)
Changeover flap, stage 2
(open)
Resonance tube, cyl. 5
(inlet end)
Due to the piston stroke of only 82.4 mm,
three resonance tube lengths are required to
achieve resonance effects in the lower engine
speed range.
Changeover points:
– Long to short
at 3,280 rpm
– Short to long
at 3,120 rpm
– Short to shorter
at 5,120 rpm
– Shorter to short
at 4,920 rpm
Injector
mounts
SSP282_017