gio64

iTrader: (1)

Hi,
I installing a BC in my car (and making a writeup as I go along).
I have a quick (hopefully) question.
The line coming from the turbo is a 6mm hose. The BC solenoid comes with fittings that are smaller (I'd say about 4.5 or so).
What should I do?

Buy a 6mm fitting to screw on to the solenoid and go from turbo to solenoid directly, or buy a reducer to step down from 6 to 4.5 (or whatever that is) and keep the original solenoid fitting?

Difference would be that the original fitting has a smaller size internal bore going into the solenoid. As far as I can think, this shouldn't really matter, but I know many around here know better.

Thank you,
Giovanni

gio64

iTrader: (1)

come on boys, no suggestions?

scotty305

iTrader: (2)

I believe there is a restrictor pill in the vacuum line between the compressor outlet and the OEM wastegate control actuator, so a 4mm line might not make much difference compared to a 6mm line. If possible, I'd use 6mm hose with an adapter at or near the boost control solenoid.


FYI, the wastegate solenoid is not the only output used by the stock ECU to control boost in the OEM twin-turbo setup. At low RPMs, the stock ECU changes the duty cycle of the prespool solenoid to control boost. At low RPMs the ECU holds the wastegate shut and uses the Prespool valve to divert exhaust gases away from the primary turbine in order to prevent overboosting.

gio64

iTrader: (1)

Thank you for the help. I knew about the restrictor pill in the line, in fact, I was looking at it after I removed the stock line from turbo to wastegate.
I was more pondering about whether or not the operation of the solenoid I am installing would be affected by receiving a 6mm line instead of the 3/16 (I think) that it comes with, but I guess it really doesn't make a difference...
I did find a barb fitting that goes into the solenoid and is the 6mm size that the stock calls for, I prepared the solenoid to receive the 6mm hose.

Thank you for the information about the prespool. I have been reading a lot about the system, because I have to decide which way to plumb the solenoid. I read that many still don't understand exactly how wastegate and prespool work, but what you're telling me sheds more light in that direction.
After thinking about it for a long time, I have decided to give a try to the version 2 modified. In other words, one line from turbo to solenoid, one from solenoid to wastegate, one from wastegate to prespool (is it Pre-Control Actuator?) and the line out of this capped.

Conversly, I hit another snag because I don't know where to place the solenoid in the engine bay... I am still thinking about it.

scotty305

iTrader: (2)

Lots of good info about the twin turbo conrol system in the Service Highlights Manual. You can find a link to the service manuals in PDF form here in the 3rd Gen FAQ thread.