Cylindrical Objects In Air Inlet

[gregoir]

An idle question on a cold dark afternoon. In the 1.4tsi air intake system are three cylindrical objects , side by side and at right angles to the airflow. Are these some kind of noise generator? I'm thinking they look rather like a short set of pan pipes.

[SWBoy]

They're to generate pressure resonance at 3 different frequencies (=engine rpm) which will improve filling of the cylinders at those frequencies to enhance power/torque.

 

It's a well used "trick" in high performance engines which is being increasingly used on all engines.

[gregoir]

Thanks for that prompt reply. Is there term for this 'trick' - Helmholtz resonator springs to mind. Just want to look up the principle as I've not seen those devices before. The performance astounds me and there is a rorty sound to my old ears!

Edited 18 November, 2017 by gregoir

[SWBoy]

46 minutes ago, gregoir said:

Is there term for this 'trick' - Helmholtz resonator springs to mind.

Nothing more exciting than "intake resonator" - Google finds plenty of matches.

 

I first saw it used in the late 1980s when I was working at an automative consultancy, but it probably predates that...

[gregoir]

Err yes, a Gòogle search only reveals loads of boy racer types removing their resonators. But the actual  resonator theory seems indeed to refer to Helmholtz resonators which do maximise airflow at medium rpm. 

Edited 18 November, 2017 by gregoir

[themanwithnoaim]

5 minutes ago, gregoir said:

But the actual  resonator theory seems indeed to refer to Helmholtz resonators which do maximise airflow at medium rpm. 

& at a full 6k before upshifting they sound Fn great

[gregoir]

At least there seems to be a "sound" reason for those resonators rather than the noise generators in the Vrs?

[Rooted]

http://briskoda.net/forums/topic/439707-under-the-bonnet