I was not happy with the Dawes/Needle setting, although I got it to work.
For me, this arrangement is missing one level of freedom to make sure we get the best out of the VNT.
This is why I am about to install the following arrangement :
Attachment 76221
The first needle, is used to set the maximum opening of the VNT, which stays shut up until the dawes open.
And then the second needle is tuned to set the speed at which the VNT will open, and decrease the speed of pressure increase with RPM.
Not sure if it is clear for you, but it is for me.
The VNT range of opening goes from -465mbar (closed) to -220mbar (open).
If you set the Needle to get -465mbar in the vacuum hose, when the dawes open, the vacuum goes direct to -250mbar, and the VNT is opened. I wished it would be more continuous, which is why I decided to insert another needle behind the dawes, so as to make the dawes open a bit sooner, but manage the level of vacuum more precisely vs RPM by opening or closing the second needle.
Any comment welcome.
Cheers