[s-cars] Thermal properties of anodizing Aluminum

[mlp qwest]

Jonathan -

Thanks for the input.  Yes, 400F might be a slight over statement as re
charge air temperature, but not, IMO I don't think its by very much.  And
maybe not really even at all.

Maybe Hap has some better notes, but based actual Davtron readings, I've
seen @340F with an RS2 turbo pushing somewhere in the @ 24 to 25 psi range
going up I70 towards Evergreen.  And I think that was more like on @ a 70 or
so ambient temp day, IIRC.  Take the 95C (@ 205F) isentropic reading you've
worked out & assume you've moved your self even just outside the 60%
efficiency island on a turbo compressor map, and I think (?) one can make an
argument you would soon be running anywhere from 340F & up as a turbo
discharge/ intercooler inlet temperature.

Would it be fair to say certainly K24's, and even the RS2's, aren't in their
happiest delivery (efficiency) modes once you pass 4,000 rpm and are calling
for more than 25psi of boost...., especially at 5,500+ feet.  My impression
is the smaller KKK's are very inefficient in that range, if in fact that
kind of volume is really even "on the map."

As for the reason, following on Brian Billotti's IC idea/example, it's
mostly for cosmetic purposes to try to make the install a little less
conspicuous.  After going through the time, trouble and expense of getting
the new IC made up and fitted, I'd rather not sacrifice a lot of its
functional purpose for cosmetic reasons.

I suppose a secondary benefit might be a little protection for the aluminum
from external elements.  One option I understand is available with
anodizing, including, I think type II, is a second bath to "seal" the
aluminum oxide.  If one were to do a complete emersion filling the interior
of the core, rather than "sealing off" the interior, both the inside, as
well as outside fins could be anodized.

I've currently got a stock aluminum IC off a car to fit for a set of davtron
sensors & pressure feeds (photo attached.)  That sucker is still dripping /
seeping oil if you hang it up for awhile even after 2x trips to the car wash
wand & a good dousing with cleaning solution.  I think one needs access to a
steam cleaner to come anywhere close to getting the inside cleaned out.

My understanding is aluminum, especially cast pieces, depending on the alloy
& finish can be pretty porous.  An anodized internal finish should help
prevent it from seeping into the ÏC core.  I'm not sure what thermal effects
the build up of an oil coating has on an IC.  My assumption is they more
detrimental, than beneficial.

Mike "Hey Hap, you can get this done in Ricer Purple too, to match your XS
BPV's" Pederson

~-----Original Message-----
~From: J. Khang [mailto:jhlk99 at yahoo.com]
~
~Actually, an isentropic (perfect) compressor will only
~raise the temperature to 95C. I tried to calculate the
~actual temperature rise but there are too many
~variables whose value I don't know.
~
~I think that 110-150C is more realistic, 400F (205C)
~is too high unless the compressor is very inefficient.
~


~
~Why are you anodizing?
~
~Jonathan
~'96 S6
~