[s-cars] Too much boost

[Tom Mullane]

Joe,

I took a good look at this diagram you sent, and I have some questions:

http://pictureposter.audiworld.com/47312/manualboostctrl.jpg

Is this based on theory or actual practice?  I ask because I'm not
sure it will work.
I do understand the theory behind it; either the manual controller or
the WGFV can limit boost.  In other words boost will be no higher that
the lower setting of the two controls, ECU via WGFV or manual
controller.

It looks great on paper, but here's the problem:
The WGFV takes boost from the turbo and either routes it the WG to
force the WG open and limit boost, or it just dumps the boost back
into the intake track just before the turbo, allowing boost to build,
right?  Wrong...sort of.

When the WGFV is closed (default, unplugged, failsafe, yada, yada) it
routes all boost to the WG to open it.  But when power is applied the
WGFV, opening it, it allows boost into *both* passages of the "T". 
Boost bleeds off into the intake boot and cannot reach the WG with
enough pressure to force it open.

My concern is thus:
Let's say I install a manual controller and set it to 20 psi.  The ECU
is calling for 30 psi max.  At anything less than 30 psi, the WGFV
will be bleeding off boost in the control circuit into the intake
boot.  There will not be enough pressure in the circuit to reach the
manual controller.  Even if pressure reaches and passes the manual
controller, won't it just be bled off through the WGFV before it can
impact the WG?

Does this make any sense to anyone?
Has anyone BTDT?
Pressure may not bleed off fast enough to create a problem, but I have
my doubts.

Tom 

On 8/10/05, Joe Pizzimenti <joe.pizzimenti at gmail.com> wrote:
> Tom,
> Did you try turning it down via a manual boost controller plumbed
> inline with the WGFV?
> 
> http://pictureposter.audiworld.com/47312/manualboostctrl.jpg
> 
> Joe
>