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[Svo] Boost Solenoid {4}



Mike Ray wrote:
> 
> As I understood it... With the solenoid bypassed, there's no bleed off
> to the atmospere causing the wastegate diaphram to open as soon as 10
> psi is pushing on the diaphram. 

I think either you're confused about where all the hoses go, or else
we have different definitions of the word "bypassed".  My definition
of "bypassed" is the same as if the two hoses attached to the solenoid
were attached together and full flow was allowed through them.  This
is the route that the "bleed off" air takes, which means that when
the solenoid is bypassed, pressure is always being bled off from the
diaphragm.

> On mine, if you take off all the SVO
> crap off and run straight hose, it'll open at the same psi as the older
> turbo cars. 

True, if you take ALL the SVO crap off, including the tee, and just
run a single hose straight from the compressor outlet to the
diaphragm.  The hose through the solenoid is the bleed off...when
the solenoid is open boost is high (but limited by the orifice
size in the tee), and when the solenoid is closed the diaphragm sets
the boost at ~10psi (whatever the exact number is).

> I thought the 10psi # came from the strength of the spring
> in the diaphram.

Yup.  I think a lot of people get it turned around and think
that the solenoid is in the path to the diaphragm.  It's not,
it's in the bypass path.  If it were the other way, when the
solenoid closed, boost would be uncontrolled and would run away...

-- 
Carl_Morris@StorTek.Com