Electric water pumps (was) alt charging cont sw

[steve ravet]

Greg Hermann wrote:
> 
> >-----Original Message-----
> >From: steve ravet <Steve.Ravet at arm.com>
> >To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> >Date: Friday, March 12, 1999 2:50 PM
> >Subject: Re: Electric water pumps (was) alt charging cont sw
> >
> >The reason water pumps are such a large HP lose is cause they need to be.
> >You
> >can slow em down some, and in some applications take em out.  But, for a
> >street motor,
> >they is what they is.
> >  For you to have an electric motor pump as much as an oem waterpump you'd,
> >have to have a
> >big a-----  motor/pump to replace it.
> >  For fast warm ups use a recirculating thermostat
> >Bruce
> 
> Bruce is right on this, completely. (Or is it one of the little guys?)
> 
> There is even a good debate possible as to whether a high pressure fuel
> pump should be electrically or mechanically driven, let alone a water pump,
> or an engine fan (if you are working an engine any kind of hard at low
> speeds for any length of time)!
> 
> For any sizable auxiliary drive loads, a mechanical drive is way more
> efficient than an electrical one.
> 
> Regards, Greg

But, isn't it inefficient to spin all those things at engine RPM rather
than a constant RPM?  Seems like a pump/compressor that has to work over
a 10:1 input speed ratio wouldn't be as efficient as one designed to
work at a constant RPM.  Like A/C, and esp power steering.  If those
were designed to run w/electric drive at constant RPM maybe they'd be
more efficient.  Especially if you had a dual voltage alternator and ran
the accessories at 100V 3phase.  maybe?

--steve

-- 
Steve Ravet
ARM, INC
steve.ravet at arm.com
www.arm.com