Re: Controlling Turbo boost

[ptimmerm@mashtun.jpl.nasa.gov]

   >>>.. in 1st and 2nd gears,
   >>>the RPM/Boost build too fast and can cause the ECU to cutout
   >>>before the air pressure regulator as settled and stabilized at it's
   >>>lower-than-peak holding point.

   >>I don't quite follow here Robert.  My experience, although limited,
   >>is that boost fed counter-pressure rises slowely.  Less c-pressure
   >>means less boost, thus how do you get over-boost.  Is the counter-
   >>pressure left over from first gear as you shift into second?

>No - it "takes a second" for the air pressure regulator to stabilize at
>4.0 (nominal) PSI, after peaking "briefly" at nearly 5 PSI while the
>turbo builds up boost. In (e.g., 3/4/5 gears), as I run the engine up,
>I can see the boost go up to 15, then "settle" back to 14 as the regu-
>lator stabilizes...

	O.K Gottcha.  My regulators dont do that in my car. They go up
	to the there limit and hold nicely, without over-shooting.


>So half the question (well, it's a full question in its own right) is
>why does the turbo build up 12PSI at 5000, and not stay at 10PSI, as
>at 3000rpm. Is my wastegate sticking? Could the S4 turbine/housing
>actually be too small (and sensitive, so even with the stock wastegate
>wide open, it still spins "too" fast? (i.e., do I need a bigger waste-
>gate, or bigger ex- haust turbine? 

	The undersized wastegate would be my guess.  Sounds like
you need...  fanfare  .... Schrappnel Knobben!!!  With rock steady
back pressure you could dial in at a level that accomodated the 
rpm rise nicely, albiet lose a little at lower r's.

>Now if someone ever gets their RS2
>act together and starts offering them to all'uh'us nut cases...)

I was talk'n to Nor Cal Turbo, and they would be happy to order 
some up from KKK.  They say KKK is kinda funny, like if you can't
recite part numbers backwards and foreward in german while 
polkaing they won't sell to you.  So if anybody is willing to cough
up the VAG part number, we can all (possibly) have the kompressor.

paul t-