The other line is there so both sides of the diaphragm see filtered air, but its not that important and not all vw t3s have, and almost every wastegate can works like that where one side is open to atmospheric pressure and one side sees boost pressure. But obviously the filtered air is best
You're right Lucas. The only reason I can think of for the extra line is to allow a bit of airflow on the diaphragm to keep it cool.
I am always right LOL.
I can only think that it is there to help airflow over the diaphragm as you say and possibly route some pressure back to the turbine and help spool.?. As it looks it is cut in there at the right angle to keep the blades going the right way. In a stock application with no boost controller it would be blowing constantly. Could be off on that one but there is a reason vw did it and no one else did.
So leave it open? Or run it to the hole in the turbo?
How would I run a boost controller.
Boost controller you would need to interrupt the BIG threaded line on the wastegate and have it installed somewhere between there and the compressor housing.
I would hook it up. I am adding it to my Merc housing as I have had some turbo issues. I figure it cannot hurt.
Must just be a fitting with a hard vacuum line that runs into the rubber hole on the turbo.
Yes, just a banjo and hard line as far as I can tell.