Resonance Intake System Task/Design/Function
Model 210.020;
(USA) only up to O5/96
NOTE: The resonance intake line switchover valve (Y22/7) is positioned at the engine end.
Model 210.020 (USA) as of 06/96
NOTE: The resonance intake line switchover valve (Y22/7) is positioned at the engine end.
Task
Improving the torque curve in the lower rpm range without any decrease in power in the rated engine speed range, as a result of different intake pipe lengths.
This engine is particularly suitable for this measure in view of its firing order of 1-5-3-6-2-4 as splitting the intake system into cylinders 1-3 and 4-6 results in three cylinders each breathing from a resonance pipe with an ignition spacing of 240° CKA.
Design
A pneumatically operated resonance flap (99/2, 99/4) is located in the intake line and in the intake manifold.
The resonance intake line switchover valve (Y22/7) and resonance intake manifold switchover valve (Y22/6) are located below the intake manifold, between cylinders 4 and 6.
They are actuated by the IFI control module (N3/7).
Function
The pistons produce a strong vacuum in the suction stroke which sets the air content of the intake manifold in motion when the inlet valve is opened. As a result, the inflowing air develops a considerable kinetic energy. When the inlet valve closes, a dynamic pressure is produced which begins to expand immediately in the opposite direction. The level of the pressure depends on the mass of the gas quantity which is in the intake manifold. If the air column is accelerated and decelerated in rapid succession, this produces a vibration, the frequency of which is dependent on the length of the intake manifold. If the engine timing is harmonized to the vibration of the air column, a boost effect is achieved as a result of the resonance vibration of the air column. The vibrations of the air column also depend on engine speed, as a result of which it is possible to improve the resonance vibrations with a given length of intake manifold only within a certain engine speed range.