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Re: Bypass valve effectiveness?

Hi all:

Graydon D. Stuckey wrote:

>        If I shift gears without lifting my foot off the accelerator,
>will that allow the turbo to keep spinning while I shift gears?   
>        Thoughts?  Rebuttals?  Is there another reason for the bypass

The valve is really a safety valve as opposed to a performance item, 
to help prevent stalling the compressor, as well as prevent the 
pressure spike in the intake manifold when the TB is rapidly closed.  
In the Audis I have seen, the compressor does not have much of a 
tendencey to stall, (although I imagine there is a pressure spike) but 
in my other car, (87 Grand National) the compressor will stall even 
with moderately slow closing of the TB.  Once I heard this happen in 
this car, I ran and got a blow off valve.  Stalling the compressor 
wheel is _very_ violent, and something no one wants to hear.  (once in 
a while I hear of a compressor shearing off in these cars, what a 

BTW, my 5ktq has never made a noise like that, and I'm sure a bypass 
valve would be a good idea to add, but it is low on my list of things 
to do... 

Kevin Ford