Date:         Tue, 1 Apr 2003 08:34:31 -0800
Reply-To:     laurasdog@WEIRDSTUFFWEMAKE.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Steve Delanty <laurasdog@WEIRDSTUFFWEMAKE.COM>
Subject:      Re: Van runs hot in traffic jams
In-Reply-To:  <200304011103.AA1570832674@intrex.net>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 08:03 AM 4/1/2003, you wrote:
> >The fans were added to modern cars because the newers >vehicles were more
> >tightly cowled and that restricted airflow. Additionally, >the newer
> >aluminum engines are more susceptible to heat damage that >the old cast
> >iron block engines. Thus the automatic fans.
>
>Yeah, but the fact that rear engine and front transverse mount engine cars
>can't have an engine driven fan is probably a big reason too!
>
>Bill

Electrics also have an efficiency advantage.
A mechanical (engine driven) fan has to be sized
large enough to move an adequate quantity of air
at idle and low RPM (sitting in traffic). That means
that at high RPM they usually move way more air
(and eat up way more HP) than required. Even at
70 mph when there id plenty of air flow across the
radiator without any fan.
Mechanical fans can suck up a LOT of HP at
high RPM. Flex fans and fan clutches help some,
but not all that much.

An electric on the other hand runs at a constant
speed and doesn't increase it's HP requirement as
engine RPM goes up. Plus, the electric is turned
*off *most of the time when the vehicle is in motion
and only eats power when the cooling system
requests it...

Less HP required for cooling = better fuel economy.

Steve