RE: Max Boost/HP? 87 5kcstq

[Todd Phenneger <phen9461@uidaho.edu>]

On Fri, 26 Mar 1999, Mike Sylvester wrote:

> 	I don't believe that it is the 14psi boost that blows apart the IC.
> I've found that
> 	when the hose or IC blows it is not under max boost, but just after
> the throttle
> 	released after full boost.  At this point the pressure in the IC
> goes way up.  Well
> 	beyond the 14psi, because the turbo is still generating max boost
> and you have just 
> 	closed off the airway by closing the TB.  I've also destroyed an ISV
> from this.
> 	Once the TB is closed, the ISV is the only open airway.  I believe
> it is the ISV that
> 	makes the whistling sound after throttle release.  

	Ahh yes.  When the Throttle Plate slams shut there is a massive
Pressure Spike between the Turbo and TP as you said.   This is one reason
that a Pop-Off Valve at the Michlin Man Hose location (takes a different
hose) is so helpful.  And if you use the 20v system or similar you can
route the pressure back to pre-turbo to keep it spooled up during shifts.
:-)
 
> 	After blowing up the IC in my 87 5K, I bought a hot water heater
> blow off valve from the hardware 
> 	store.  It opens at 30psi.  I drilled a hole in the plastic tank of
> the IC and mounted it.
> 	Since the plastic tank had already been removed for me, it was
> simple.
> 	I never had any problems afterward.

	I rest my case.    Seems we agree.  Now, if you can, route it in
to pre turbo and see if that helps lag between shifts at all.  I would
maybe use a 20psi unit to get maximum air going to pre-turbo but thats up
to you.  Just an Idea.  I know some like this arrangement but some people
with Very Modded k24 10v's seem to thing it doesn't do anything.  I know
Audi used it on the 91- 20vt and the newer 20v's so I assume it works.  I
have not BTDT though.  (YET)
	L8R
		Todd