Re: High Altitude???

[Pcarselle <pcarselle@worldnet.att.net>]

Avi Meron wrote:
> 
> Pablo,
> Any supercharger regardless of the method driven (exhaust or mechanical)can
> compensate for altitude (that is why they are used in aircraft's)...
> Avi
> 
> > -----Original Message-----
> > From: owner-quattro@coimbra.ans.net
> > [mailto:owner-quattro@coimbra.ans.net]On Behalf Of Pcarselle
> > Sent: Thursday, July 30, 1998 1:29 PM
> > To: Powells@ezlink.com
> > Cc: quattro@coimbra.ans.net
> > Subject: Re: High Altitude???
> >
> >
> > Powells@ezlink.com wrote:
> > >
> > > Friends, since I arrived in Fort Collins, CO (just north of denver) I
> > > have noticed that the boost in our 1990 200 rarely goes above an
> > > indicated 1.1 bar.  On occasion I can get the normal 1.3 to 1.4 bar,
> > > but not dependably.
> > >
> > > I found that gas up here is 91/87/85 (premium/plus/regular) octane,
> > > as opposed to the 93/98/87 which I found in Texas.  I also found
> > > that my wife had been filling up at a Sinclair station.  I wondered if
> > > the Sinclair gas's octane might be too low, causing the engine to
> > > knock and timing to be retarded, causing in turn a lack of boost...
> > >
> > > I tried filling up on premium at a Texaco station (posted as the
> > > same octane, 91) and the situation has not improved.
> > >
> > > Any thoughts on the possible cause?  I can certainly check timing,
> > > etc., but thought I would ask for group wisdon.
> > >
> > > PS:  YES, I have thoroughly checked the intercooler hose, and it
> > > has no cracks or failures in the area where the oil collects.  BTDT
> > > already a few months ago.
> > >
> > > TIA for any (constructive) thoughts).  Also FYI - my Audi page and
> > > Audi FAQ pages should re-appear within a week.
> > > ++++++++++++++++++++WSU-CSU+++++++++++++++++
> > > Al Powell
> > > Powells@EZlink.com
> > > 1958 Fiat 1200 Spyder "Transformabile"
> > > 1983 Datsun 280ZXT
> > > 1990 Audi 200
> > > ++++++++++++++++++++++++++++++++++++++++++++++
> > Powell:
> > In my opinion you have decreased atmospheric pressure. Less intake
> > volume therefore less exhaust volume. Superchargers not exhaust driven
> > can compensate. ECU compensation can address timing and in some systems
> > spray duration but not air (molecules) volume.
> > HTH.
> > Pablo
> >
Avi:
Thanks for input. How can an exhaust driven supercharger (Turbo ?)
compensate ?
Where am I wrong ? Please help me !
I thought less volume of air at intake resulted in less exhaust volume.
Therefore less CFM's to drive superchargers.
Is it then that a Turbo at sea level and at 12000 ft. provide the same
boost ? by compensating ?
Mechanically driven turbochargers are of course self explanatory.
Your help will be appreciated
Thanks in advance
Pablo
P.s. I measured (long time ago ) internal combustion engine vacuum at
12000 ft.  and it was about 2 inches of mercury less than at sea level.
Engines seem to breathe less. 
Compression drops substantially, Power  and Torque follow.
I am getting old
Pablo