Re: K24 and boost - more on WGFV

[QSHIPQ@aol.com]

In a message dated 12/5/99 3:31:21 PM Central Standard Time, 
orin@WOLFENET.com writes:

>  
>  Oh but the pressure at the vent does have an effect.  It _is_
>  an input to the system.  0% duty cycle, pressure in wastegate
>  upper chanber = 'vent' pressure.  100% duty cycle, pressure
>  in wastegate chamber.  Some horrible function of duty cycle inbetween.
>  The pressure at the 'vent' doesn't go away once the FV starts
>  cycling...  The DC required to maintain a given pressure in the
>  wastegate _will_ change with different pressure at the 'vent'.
>  Vent to atmospheric and you would require slightly lower DC.
>  It may not be very significant, but I'd still call it an input
>  to the system...

I measured this, several times in fact Orin.  I found less than 1 psi 
difference between vacuum and open.  The car did the identical times in the 
1/4 miles (I posted this some time ago), and I discounted the 'vacuum' theory 
because isolating it, didn't change things enough to measure.  A whole bunch 
of other variables (including spring stiffness variance and PT variance car 
to car) could account for that 1 psi.  I know I'm not the only one that tried 
this experiment.

>  
>  > Call it semantics, I think it calling a FVDC "vent" an input, only 
causes 
>  > confusion here. 
>  
>  I have no problem calling it a vent... and leaving it at that...
>  
>  Orin.

Thanks, that's consistent with the audi documentation. 

Scott J