[DeTomaso] Flex-a-lite question

[MikeLDrew at aol.com]

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
-------------- next part --------------
   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