Re: fan power needed

[James Montebello <jamesm@domain.elided>]

On Sun, 1 Dec 2002, Ferdinando Di Matteo wrote:
> It seems I remember the engine driven san uses 7 horse power.  I am
> sure the electric fans, esp in the V6s use more.  the 40 anp fuse in
> the 164 is a clue.  the idle speed is controlled so you won't see the

40 amps * 12 volts = 480 watts, which is less than 1hp.  (roughly 750 watts
per hp, can't remember the exact conversion figure off the top of my head).
Typically, alternators are about 50% efficient, so figure about 1kw of power
is taken from the engine to drive the alternator to power the fan.  This is
still less than 2hp.  I don't know the rated size of the 164 alternator, but
90 amps is pretty common for a modern car.  This would consume 3.5hp at the
rated current, tops.

People have been claiming 10hp loss from cooling fans for decades, but the
numbers just don't add up.

james montebello
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided