GF09.20-P-6002MIK Component Description For the Variable Intake Manifold
GF09.20-P-6002MIK Component Description For The Variable Intake Manifold
- ENGINES 272.942 in MODEL 171.454 as of Model Year 09 / AEJ 08 model refinement package
View of the engine from above
12 Variable intake manifold
Location
The variable intake manifold is located in the middle between the cylinder heads.
Task
The variable intake manifold optimizes the engine torque curve using two different intake manifold lengths.
Furthermore, the air stream is improved through tumble flaps which can be swung in and out of the intake ports.
Design
The variable intake manifold is made up of several magnesium pressure castings. During assembly, the individual intake manifolds for each cylinder and the air manifold collecting sections are in the center.
There is a total of four shafts mounted in the variable intake manifold (two tumble flap shafts and two variable length intake manifold switchover flap shafts).
The vacuum supply for the vacuum units is provided by a vacuum reservoir in the variable intake manifold when the switchover valves are actuated.
The reservoir volume is designed for several actuations without having to be evacuated again.
The housing for the variable intake manifold must not be disassembled!
View from the top left
12 Variable intake manifold (with integral vacuum memory)
17 Fuel rail
17/1 Fuel pressure reservoir
22/6 Intake manifold switchover vacuum unit
22/9 Tumble flap switchover vacuum unit
51 Pressure gauge connection (fuel)
B2/5 Hot film mass air flow sensor
B28/9 Left intake manifold tumble flap position sensor
M16/6 Throttle valve actuator
Y22/6 Variable intake manifold switchover valve
Y22/9 Intake manifold tumble flap switchover valve
Y62 Fuel injection valves
View from front
12 Variable intake manifold (with integral vacuum memory)
12/1 Tumble flap shaft, left cylinder bank
12/2 Tumble flap shaft, right cylinder bank
12/3 Variable length intake manifold switchover flap shaft, right cylinder bank
12/4 Variable length intake manifold switchover flap shaft, left cylinder bank
22/6 Intake manifold switchover vacuum unit
22/9 Tumble flap switchover vacuum unit
Y22/6 Variable intake manifold switchover valve
Y22/9 Intake manifold tumble flap switchover valve
Function
Intake manifold changeover The individual intake manifolds, each approx. 800 mm long, are arranged in a spiral shape around the air collecting volume. Each single intake manifold has a further opening to the air collecting volume somewhere in the middle. This opening can be opened or closed by rotating longitudinal switch flap shafts. The variable length intake manifold switchover flaps of a cylinder bank are interconnected via a shaft and are each actuated for by an intake manifold switchover vacuum unit.
Both intake manifold switchover vacuum units are connected via hose pipes to the variable intake manifold switchover valve.
When not actuated, the switchover flaps are opened by springs in the intake manifold switchover vacuum units and thus open the short intake tract.
Tumble flap switchover
The tumble flaps can be swiveled in the variable intake manifold for partial load in every intake port. In this way the cross-section of the intake port is reduced by about 50%.
The flow rate of the intake air increases and ensures better distribution of the fuel air mixture in the combustion chamber.
The tumble flaps are located on two tumble flap spindles, which are actuated through a linkage by the tumble flap switchover vacuum unit.
The tumble flap switchover vacuum unit is linked to the tumble flap switchover valve by a hose line.
When not actuated, the tumble flaps are swiveled out by a spring in the tumble flap switchover vacuum unit, and thus open the intake ports.