Subject: Re: [s-cars] A/C

[Joseph Pizzimenti]

Thanks for the info, Wayne.  What I'm wondering is,
can it be done without draining as much power?  This
could be the mod for those with too much cash and not
enough readily available parts.  :-)  Has anyone btdt?
--- Wayne Dohnal <dohnal at hevanet.com> wrote:
> I'll dust off the rusty engineering skills and take
> a crack at answering why
> the A/C is run off of a belt.  I've heard that the
> A/C takes about 5 HP from
> the engine.  Starting with this assumption, that
> means an electric motor
> would need 3730 watts, which at 14 volts is about
> 266 amps.  But since the
> motor won't be 100% efficient, it would draw over
> 300 amps.  IF we had an
> alternator that could handle this draw, it would
> just transfer the drain on
> the engine from the A/C pulley to the alternator
> pulley, but require more
> engine power because of the losses in the alternator
> and wiring.  To counter
> this, the system could use a hermetically sealed
> compressor like most
> electrically-driven refrigeration units, which would
> give us a huge increase
> in reliability and I'd assume a more efficient
> system.  A car A/C system is
> considerably more powerful than a typical window A/C
> because of the
> tremendous amount of solar heating through the
> windows.
>
> Wayne Dohnal
> 1994 S4
>
>
> <parts of post snipped>
> >My next question is that since our compressors
> >are so ancient and will probably need to be
> replaced
> >anyway, has anyone come up with a solution that is
> >less power draining than having it run off a belt?
> I
> >was thinking of an electrical source rather than a
> >pulley, being drawn from the alternator?  Just a
> bit
> >of curiosity here and frustration at losing some
> >performance when at WOT on hot days...which I
> probably
> >shouldn't do before I load up on a nice big
> >intercooler, anyway.  Anyone BTDT?  There is the
> space
> >in our bay, but can it be done?
>
>
>


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