Intake Manifold Function

Section through variable intake manifold at cylinder level

The control flaps are opened when starting and at low engine speeds. The intake air follows the shortest path and passes from the distribution volume to the cylinder with minimal friction losses.

At a load of more than 50% from approx.1750 rpm up to approx. 3900 rpm, the control flaps are closed. The intake air has to flow along the entire intake manifold. This length is selected so that the pressure waves produced by the inducting piston arrive in time at the next inlet track ahead of the open inlet valves. This ensures improved cylinder charge and thus an increase in engine torque.

At higher engine speeds (e.g. from 3900 rpm) the actuation to the variable intake manifold switchover valve is interrupted - the control flaps open as a result of the spring pressure. As a result of the shortened path, the pressure waves also pass in time, even at higher engine speeds, to the combustion chamber before the inlet valves close.