5ktq and boost ...........

[Ben Swann]

On Thursday, June 13, 2002 11:34 AM, Ken [SMTP:auditude at get.net] wrote:

[Ben, it really seems like you may have the boost valve hooked up
incorrectly.  I would perhaps take it completely out of the equation,
plugging the holes, and see what kind of boost you build then.]

Ok I will try that, especially since I have tried most everything else.

I did hook this up referencing a diagram on the SJM website.  Hooking it up
this way did strike me as being "bass ackward" now I recall.  I did test it
remained close while control port under pressure or atmospheric and opened
when vacuem applied.  That didn't really tell me which way the flow should
go - for that I referred to the diagram.

> Ben Swann <bswann at worldnet.att.net> wrote:
>
> I can't see where the bypass could be leaking to the outside
> - I'd see some crack or something, right?

[It's probably not leaking to the outside, it's just letting your turbo
potentially overspin, since the air is is circulating around and around
itself.]

Ok, that is what I thought,  and just wanted to hear it from someone else.

> Let's assume the bypass might be leaking (internally) -
> why/how would that effect the observed boost pressure?

Because the turbo is spinning around and around, but the boost isn't
"building" because it's not filling cylinders with a fixed volume.  It just
circulates, even with the throttle open (if it's hooked up wrong or
incompletely)

> > Also, since it wasn't entirely clear in your post, I just wanted
> > to make sure that the bypass is sending it's air to the
> > intake (compressor) of the turbo and not into the actual
> > turbine...I am guessing by turbine you just meant turbo.....
>
> Right - I have a fitting installed in the turbo intake, and
> directed toward the impeller.  I did this so the bypass flow
> would enter already going in the right direction.

[Is the little vacuum nipple hooked up to intake manifold pressure?  It has
to be to stay closed under boost.  Otherwise it will leak.]

Yes, and I tested the funtionality prior to installation.  Of course not
with any significant pressure or vacuem that could induce a failure mode.

[If it's a stock valve, it could be that the diaphragm is ruptured.]

Yes it is a stock bypass valve.

I'll replace it with a "cork" inline and see what happens.  I hope I don't
blow anything..else.