[urq] Upper Wastegate Hose on '83 Ur Quattro

Charles Baer charlie at istari.com
Tue May 4 22:08:23 EDT 2004

There better not be any flow out of that port, unless you have a torn
diaphragm.  When the wastegate opens, it is letting engine exhaust bypass
the turbine.

I concur with the senator from Kaleefohnia, the top port is for a reference
pressure to balance against the IM pressure.  Feeding pressure into the top
port with a schrappnelknobben delays wastegate opening by lowering the
pressure differential on the diaphragm when boost increases.  Tapping into
the pre-turbo intake tract will increase the boost pressure 
differential, admittedly
by a small amount, and open the wastegate earlier than it would with the
port vented to atmosphere.


Justin wrote:

>Yeah, I've seen the vacuum diagrams listed on the WX in the following
>document on Martin's site: http://www.quattro.ca/Urq/urq-IST-MaintAdj.pdf
>As using the Igloo port as a vacuum for the "Evaporative emission control
>system"..basically the gas tank venalation...which I don't think the WR's
>had... (as far as I know...).
>So, connecting the wastgate port to the Igloo should be o.k., since the
>vacuum created in the line is small....and would allow air to vent into the
>intake system once the gate opens....
>    I think is just matter of your personal preferece...
>----- Original Message -----
>From: "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>
>To: <urq at audifans.com>
>Sent: Tuesday, May 04, 2004 5:01 PM
>Subject: RE: [urq] Upper Wastegate Hose on '83 Ur Quattro
>... I don't see any way that it would make any more sense ... that port is
>documented as a vent on the WX ... it doesn't need to be connected to
>anything ... in fact if you started drawing a vacuum there you would be
>working against the WG spring and actually causing the WG to open sooner.
>Admittedly there isn't much of a vacuum on the back side of the airflow
>sensor plate.  Its been a while since I've looked at the engine in my car,
>but I know that the line coming off the top of the igloo on the WX is
>definitely connected elsewhere ...

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