[6pack] Electric cooling fan: pusher or puller?

[Joseph Grant]

I've been watching this thread and found some of the comments interesting.
I will try to add my .02 worth, if you don't mind.  I have done a HUGE
amount of research on this subject and have a flawless system in both my TR6
as well as in my Vette powered 84 XJ6.  

*  Electric fans do not 'fail'.  I have TWO in my Jag and the car has over
200,000 miles and 12 years since I restored it.  The fans are of course SPAL
and have never failed.  Lesser quality fans might be prone to failure but
not the SPALS.  I realize all mechanical devices will fail at one time or
another, but so far my SPAL fans have been rock solid.  I have one installed
in my TR6 and it has also worked perfectly.

*  Puller fans are documented to be more efficient.  The pusher variety does
not work well and I don't recommend using them.

*  It is absolutely essential that the fan be shrouded and mounted at a
certain distance from the radiator.  Just slapping the fan without a shroud
does not allow it to run at its peak efficiency.  Something that nobody
considers and nobody talks about, but an electric fan must be shrouded.  It
is not done because of the effort that goes into fabricating the shrouding.
Go the extra mile and it will amaze you how efficient it is.

*  Controllers:  I use a controller that employs a probe monitoring the
coolant.  This is another item that might take some effort to install, but
that is the ONLY controller for my fans.  I do not have a switch mounted
inside the car.  The fan is completely controlled by the monitoring device.
I know that SPAL makes one - don't know how good it is though.  Also, I do
not 'regulate' the speed of the fan.  The fan runs at one speed and that is
balls-to-the-wall.  When the switch kicks in the fan runs for 30-40 seconds
and shuts off.  That is how much heat it sucks out.  And, this is in the
summer in South Carolina.

*  Noise:  the amount of noise depends on the type of blades the fan has.
In SPAL fans, there are two types of blades:  curved and straight.  The
curved blades will allow the fan to run a bit quieter but at the expense of
efficiency.  The straight blades are more efficient, but they are also
noisier.  Fan noise does not bother me because for one it does not last very
long when the fan runs and also I know the fans are doing their work.  The
fan is infinitely more efficient that any engine mounted fan.

*  As Bob stated, the fan only runs in stop and go traffic and not at
highway speeds.  That is the whole beauty of the electric fan.  

If you want to see what a fully shrouded fan looks like, go here:
http://www.bowtie6.com/cooling_system.htm - behind that shroud is Griffin
aluminium radiator.  It has four pegs where the shroud gets bolted through
and then the shroud has bolts that hold the fan in place.  There are none of
those plastic 'through-the-radiator' holders - which are a very bad idea
because they will eventually stress the delicate flutes of the radiator core
and cause it to leak.  

Hope you don't mind me adding this.

joe