Component description for the variable intake manifold - GF09.20-P-6002CY

ENGINE 272.911 in MODEL 204.0 up to Model Year 8

ENGINE 272.921 in MODEL 204.0/2 up to Model Year 8

ENGINE 272.947 in MODEL 204.0/2 up to Model Year 8

ENGINE 272.948 in MODEL 204.0 up to Model Year 8

ENGINE 272.961 in MODEL 204.0/2 up to Model Year 8

ENGINE 272.971 in MODEL 204.0 up to Model Year 8

Location

The variable intake manifold is located between the cylinder banks.

Fig 1: Identifying Variable Intake Manifold With Integral Vacuum Memory

Courtesy of MERCEDES-BENZ USA

Task

Engine torque development is optimized through using two different intake manifold lengths.
The air stream is improved by having tumble flaps swivel which can swivel in or out of the intake port.

Design

Fig 2: Identifying Variable Intake Manifold Design Components

Courtesy of MERCEDES-BENZ USA

The variable intake manifold is assembled out of several pressure castings. During assembly, individual intake manifolds for each cylinder and the air manifold collecting sections are in the center. A total of four shafts are mounted in the variable intake manifold. The vacuum pressure for the intake manifold switchover vacuum unit is supplied by a vacuum reservoir in the variable intake manifold when the switchover valves are actuated. The reservoir volume is designed for several operations without renewed evacuation.

The housing of the variable intake manifold must not be disassembled!

Function

Fig 3: Identifying Variable Intake Manifold Functional Diagram

Courtesy of MERCEDES-BENZ USA

1) Intake manifold switchover

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. These opening can be opened or closed by rotating longitudinal switch flap shafts. The length switch flaps for a cylinder bank are interconnected by a shaft and each actuated by an intake manifold switchover vacuum unit.

Both intake manifold switchover vacuum units are interconnected via hose lines with the intake manifold switchover valve. Without actuation, the length switch flaps open by spring force and free up the short intake route.

Short intake route (section at the cylinder level)

At engine speeds > 3500 rpm and an engine load > 50% the intake manifold switchover vacuum unit is ventilated and the length switch flap is opened by spring force.

The intake air takes the short intake route. Thus an increase in engine torque and power output is achieved.

Fig 4: Identifying Opened Length Switch Flap

Courtesy of MERCEDES-BENZ USA

Long intake route (section at the cylinder level)

At engine speeds < 3500 rpm the intake manifold switchover vacuum unit has vacuum applied to it and the length switch flaps are closed.

The intake air takes the long intake route.

The result is an improved cylinder charge and thus an increase in engine torque.

Fig 5: Identifying Closed Length Switch And Tumble Flap

Courtesy of MERCEDES-BENZ USA

2) Tumble flap switchover

In the variable intake manifold the tumble flaps can be swiveled out in any intake port at partial load. This reduces the cross-section of the intake port 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 shafts which are actuated by the tumble flap switchover vacuum unit via a linkage.