Dawes Device

[Derrick Stikeleather]

Ummm...  I'm pretty sure that the operation you are describing is that of
the Dawes Device.  Doesn't it vent off some of the pressure, therefore
creating a pressure drop?  If your running at 10psi, your wastegate actuator
would see 6 psi, because your bleeding off 4 psi of pressure.

The FDMBC is just a like a blow off/bypass valve that is inline with the
actuator.  At a certain pressure, it opens.

That's a good point about the pressure build up due to the FDMBC.  I've
never heard anyone mention that before, and I didn't think of that myself.

Later,
Derrick Stikeleather
87 Conquest TSi.

> The FDMBC will not "let all the pressure by into the actuator" once a
> pressure level is reached.  It will drop the pressure across it.

> If the FDMBC is set to 4psi, then whatever pressure that is going in will
be
> 4psi lower going out.

> The downside is that the FDMBC is also a one way valve, so that any
pressure
> built up at the wastegate actuator will not immediately go away except
> through leakage around the FDMBC ball.  So you could run into a problem
> where the boost quickly decreases and only slowly comes back.

> In summary, in the "forward direction", the FDMBC is a pressure reducer,
it
> does not open fully at a set pressure, and in the reverse direction it is
a
> blockage.

> Dave