quattro digest, Vol 1 #3802 - 15 msgs

Larry C Leung l.leung at juno.com
Fri Aug 9 01:21:24 EDT 2002

Although Bernard's answer is correct, I figured I'd answer James'
from a chemistry standpoint. Specific Heat is the measure of how much
rise that a given quantity of a substance will experience for a given
amount of added
(heat) energy. Water is one of the highest specific heat substances,
period. Oil comparatively
is not. So, admittedly without looking up specific (ha, ha) numbers, I
can say with complete
confidence that water cools better than oil. This of course is a
materials standpoint only,
and has nothing specifically to do with the nature of Audi cooling
systems and oil squirters.

BTW, aluminum has a fairly low specific heat, which is why you can grab
the aluminum foil
right out of a 400 degree F oven without burning yourself. Your water
based body at 98 degrees
F has enough specific heat compared to the aluminum to force the
aluminum's temperature
to cool to your higher specific heat body. This property works well for
cylinder heads IF and only
IF the cooling system is capably designed with enough circulation of
coolant to have water help
keep the head temps even. Then the aluminum will mimic the water. If the
cooling system does
not have even circulation, the aluminum will end up mimicking the
cylinder temps and thus
cause hot spots and thus, detonation.


> Date: Thu, 8 Aug 2002 15:16:07 -0700 (PDT)
> From: james accordino <ssgacc at yahoo.com>
> Subject: RE: more BOOOOST!
> To: JShadzi at aol.com
> Cc: audi list <quattro at audifans.com>
> Maybe the piston temps. bear much more on the oil than
> the water?  They are oil cooled, yes?  Maybe the water
> has a much larger heat soak capability?  And better
> cooling of the water?  Via good airflow through the
> radiator and an efficient fan?  I don't know, I'm just
> guessing.
> Jim Accordino
> --- JShadzi at aol.com wrote:
> > If this is the case, how come its not reflecting at
> > all in the water temps?
> >
> > Javad
> >
> > >Ding. =A0I think we have a winner. =A0I saw a NASTYCAR
> > >piston once. =A0Running like 14/1 compression and
> > went
> > >full lean as he ran out of gas at part throttle.
> > >Looked like they used a cutting torch. =A0It burned a
> > >hole clean through the dome. =A0Melted right through
> > it.
> > > EGT's can really soar under part throttle/lean
> > >conditions. =A0Totally off throttle is still hot but
> > not
> > >nearly so.
> > >
> > >Jim Accordino
> > >
> > >--- TM <t44tq at mindspring.com> wrote:
> > >> Marc-
> > >> Sounds to me like your car is running too lean at
> > >> part throttle and your
> > >> EGTs are soaring, hence the high oil temps.
> > >>
> > >> At WOT, you're going full rich and the fuel is
> > >> cooling things down.
> > >>
> > >> Taka

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