Paul,
Welcome back!
A few days ago in one of the turbo related discussions someone mentioned

using

the "auto boost controller" to manage the boost level. Do you know if this

is a

Mazda system or some after market controller?
Thanks
Dean Head

It is a stock Mazda thing. A pneumatic servo is connected to
the intake manifold and opens the waste gate when the pressure is
x amount above atmospheric. Usually 5 psi. The problem with that is it is
not what you want at high altitude so there should be a way
of over riding it manually. Disconnecting it from the
intake manifold will work.  At high altitude, say when the atmospheric
pressure is only 10 psi instead of 15 psi (sea level), you need
10 psi of boost to get the same HP you get at sea level.

It is the thing in the lower right corner.

Paul Lamar

Paul,
Thanks for the info. I was not sure how that componet functioned in the stock
setup. Now your comment about the air bleed is clear to me. On the series four
turbo exhaust manifold there is another actuator. Does it work in syncrony with
this one? It looked to be controlled by another source.
Thanks
Dean

Forgot to answer the second question. That is a valve servo that
closed off part of the early 2nd gen (87-88) turbo for faster spool up.
A real design disaster as the manifold and the turbo cracked
everywhere.
Paul Lamar

Paul
Looking at that casting it is easy to see why it would crack.
 The two runners have too much variance in the material so one will expand and contract faster
than the other. Poor casting design.
Royce

Also when the flapper valve is full open that partition wall
takes the full brunt of the exhaust blast.

Paul Lamar
 
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