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Message
On my 91 turbo
there is a vacuum pipe which comes out of the waste gate and goes to
the side of the turbo casing. It has a T for another vacuum hose connection
which goes to a solenoid in the stock installation. The engine guy tells me that
if this vacuum hose is open to the ambiant pressure, then the wastegate will be
open. If it's blocked, then the wastegate will close. All I have to do to
control the wastegate is fit a valve to this hose.
I think your engine guy has
it exactly backwards, or he turn it around knowing you're a canard guy :-)
Assuming this is a hose
that goes from the wastegate actuator (big vacuum pot looking thing) to the
compressor side of the turbo, it's using pressure to open the
wastegate. If it's blocked, the wastegate opens at the actuator's normal
spring pressure. If you leave it open, the wastegate stays shut, and
pieces of apex seals start departing the engine
:-0
You are correct about the
possibility of having a valve in the cockpit to control the boost. As I
mentioned in the long-winded post a minute ago, you can use a simple needle
valve to set the boost pressure. There's no reason this can't be in the
cockpit, and set as needed for cruise flight.
I wonder what Rusty
and Todd are doing in this area.
As I mentioned, I'm working with manual control only at
this point. The reason is that I have 9.7 rotors, and don't want to run
over about 36" of MAP, which is 3 psi of boost at sea level. When you use
a wastegate actuator, the minimum boost is set by the spring in the unit, and
I've never seen an actuator with a spring less than about 5 psi. I am
considering modifying an actuator at some point, but that's down the line a
bit. Gotta get a real oil cooler first.
Cheers,
Rusty
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