Intake Manifold: Notes
The N62 engine is equipped with a Variable Intake Manifold making it possible to reach a generous torque curve even at low engine speeds, without incurring losses in engine output at higher speeds. It ensures that the engine exhibits optimum volumetric efficiency through the entire range of speeds.
The new feature is the Variable Intake Manifold intake pipe length can be adjusted depending on the engine speed to provide efficient cylinder filling and scavenging. This is determined by the optimal matching of the intake pipe dimensions, the exhaust system and the valve timing.
The intake manifold is located in the engine "V" and is mounted on the cylinder head intake ports.
Function
In order to understand how engine speed relates to volumetric efficiency, the physical processes within the intake pipe must be taken into consideration.
To ensure that there is good airflow to the engine cylinders, the intake pressure in front of the intake valve should ideally be high. This means that good airflow (high gas molecule density) in front of the intake valve is necessary.
This is only possible if the intake valve is closed and the mass inertia causes the intake air to flow in front of the closed intake valve. The air is compressed, the pressure and the air flow increase.