Fwd: RE: [BiturboS4] RE: boost & engine load

Philip Pace pjpace at yahoo.com
Wed Nov 13 11:57:28 EST 2002

Forgot to copy the list - sorry.

--- Philip Pace <pjpace at yahoo.com> wrote:
> My unqualified opinion thinks of two things: Electronic (like you said) and
> also I think that boost takes a lot more pressure than what is idly created.
> Sure you can get rid of the vacuum, which is essentially putting things at
> normal pressure. But to build boost, I think that it would need a lot more
> pressure on the turbos. Would someone please tell us all to go read Corky
> Bell's book, "Maximum Boost"? I purchased it last year but haven't read it. I
> bet we wouldn't be asking these questions, or guessing these answers, if we
> had
> read it. :-)
> philPACE
> --- David <goodson at menta.net> wrote:
> > I still don't see any mecanical reason for the boost to stop when in
> > neutral, or when there is no load. Try to put your hand at the output of
> the
> > exhaust when you are accelerating in neutral (I know, you should have a
> > really long arm, or a friend to help you). You will feel a big increase of
> > the gas flow. This flow is supposed to generate, through the turbo, the
> > boost. I guess the reason is electronic : both wastegate valves and
> diverter
> > valves are controled by the Motronic system.
> > Quoting the "internal-use-only 2.7t self-study program", :
> > "The charge pressure of both exhaust gas turbochargers is controlled via
> the
> > common charge pressure control valve N75 (...).
> > The Motronic ME 7.1 activates the solenoid valve for charge pressure
> control
> > N75 and regulates the charge pressure via the wastegate".
> > Actually I do remember that when I had boost problems a few months ago, my
> > ABT tuner in Paris told me to have the N75 checked (and many other things,
> > of course).
> > And about the diverter valves, the manual says :
> > "Divert air control in overrun :
> > The Motronic ME 7.1 activates the electric divert air valve for the
> > turbocharger and open the pneumatic divert air valves using this vacuum".
> > Doesn't it sound more realistic ?
> > David.
> > 1999 S4 Avant ABT
> > Barcelona - Spain.

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