[DeTomaso] Flex-a-lite question

[Sean Korb]

My shroud system is mounted pusher style and I haven't seen any
problems, but I don't sustain 120MPH very often either so there's a
future experiment.   I don't have an aerospace background and I
skipped Thermo in college (and Emag and Power too... way too much
calculus and I'd had my fill in Linear Sig. & Sys.) so I'm not sure
how much I could contribute personally or professionally.

The installation was extraordinarily easy and required minimal
modification (a couple of holes drilled for the relay and a notch or
two in the shroud and removal of the old fans, of course).  It's fine
for the way I putter around in it even 6 hours to Atlanta and back.

sean

On Sun, Feb 23, 2014 at 11:23 PM,  <MikeLDrew at aol.com> wrote:
>    In a message dated 2/23/14 11 06 6, fresnofinches at aol.com writes:
>
>      I've come to the conclusion the Hall Pantera Meriah fans are getting
>      tired and are not up to the task of slow traffic cooling.
>      I say this because in Summer/Winter I now always see a large jump in
>      temp when I get into city traffic versus highway travel. 20-30
>      degrees jump. Wasn't always that way.
>
>    >>>Assuming that your fans have 'changed' somehow defies logic.  They
>    either work, or don't work.  I strongly doubt that they have slowed
>    down measurably; if so the problem is probably relatively easy to
>    address (corroded connections etc.)
>    I would be MUCH more likely to believe that you have air introduced in
>    the system.  When was the last time you checked?  When was the last
>    time you changed your radiator cap?  Do you have a proper cap that
>    matches the type of water bottle you have?
>
>      >I would rather not remount the three-pass Quella/Ron Francis
>      radiator for sucker fans, so I'm looking at pushers.
>      Felx-a-lite offers model 440 as a pusher. 2500 cfm, S-blades, etc.
>      But I noted the online-available PDF installation sheet groups the
>      440 pusher and the 420 puller in the same section.
>
>    >>>Mechanically they are the same; the only difference is the
>    construction of the fan blades.  You can't use a pusher fan in a puller
>    application and expect optimal performance.  There will be some
>    measurable degradation due to spinning a pusher blade backwards.
>
>      >It instructs the 420 puller to be wired red/red and black/black,
>      fan to power source. And to reverse the wiring to red/black and
>      black/red for the 440 pusher model.
>
>    >>>Right--the motor is going to turn in the opposite direction for a
>    pusher vs. puller application, which requires the motor to be hooked up
>    'backwards'.
>    They could have chosen to design the fan blades to do their respective
>    jobs with the motor turning in the same direction, just as easily.  But
>    they didn't.
>
>      >This tells me the fan blades are expected to perform whether
>      rotating CW or CCW. But I've always heard blades are
>      optimal for one direction only, and show reduced efficiency when
>      rotating opposite to the intended function.
>
>    >>>True dat!
>
>      >I will try to talk with a Flex-a-lite tech about this on Monday,
>      but in the meantime I'm asking for any of your ideas, thoughts and
>      suggestions.
>
>    >>>My most strident objection is to mounting a shroud-system fan in a
>    pusher application at any time.  It will block a substantial percentage
>    of the surface area of the radiator from seeing airflow.  The net
>    result is like fitting a radiator that is 20-30% smaller than what you
>    have now.
>    That's cubic dumbness.
>    If you really want one of these deals, install it in a sucker
>    application.  Those work well except they restrict airflow at much
>    higher speeds.  Johnny Woods saw overheating in his car with that kind
>    of setup at triple-digit speeds because air would stagnate on the back
>    side of the radiator and couldn't escape.  In typical Johnny Woods
>    fashion, he fabricated a series of one-way flaps that would open up
>    when pressure dictated, yet suck closed when the fans were providing
>    vacuum, and that cured the problem.
>    Seriously though--if you have Meriah fans, you have some of the best
>    fans you can buy.  Look elsewhere for your problem first.
>    Mike
>
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-- 
Sean Korb spkorb at spkorb.org http://www.spkorb.org
'65,'68 Mustangs,'68 Cougar,'78 R100/7,'60 Metro,'59 A35,'71 Pantera #1382
"The more you drive, the less intelligent you get" --Miller
"Computers are useless.  They can only give you answers." -P. Picasso