Fan air flow data - Model A Times

[steve s]

A few recent threads have asked about relative cooling ability of various radiator fans. I have tracked down a study I vaguely recalled reading. The Spring 2007 issue of Model A Times measured air flow speed of three fans: original 2-blade, repro 4-blade, 6-blade plastic, at three motor speeds: 500, 1000, and 1500 rpm, and at three locations: in front of radiator, in front of engine, at center of engine (looks to me like beside distributor over exhaust manifold).

There wasn't much difference in front of the radiator. At the two locations under the hood, the original fan was the worst at all speeds and locations. The 4-blade was best at 500 and 1000 rpm; the plastic best at 1500 rpm.

They note that the 4-blade is easily bent out of balance, and recommend the 6-blade plastic.

Not tested were either the repro aluminum 2-blade or the white plastic job that Dennis Cling sells with his serpentine apostasy (my personal choice, pictured below).

Steve

 

[Bassman/NZ]

Any data on the parasitic power loss of the different fans?

 

[Tudortomnz]

Certainly lots of discussion on types of fans & air flow. Really you can put whatever type of fan on that suits you. If an original look Model A is wanted, the new aluminum 2 blade fans look the part.. Plastic is OK for a hotrod IMO. Maybe the use of alternators/high tension belts contributes to fan & pully problems.
I like to live 'dangerously' & still have the 81 yr old factory fan on my 'A'

 

[BRENT in 10-uh-C]

You know, this is what I think is unique about human nature. I grew up in the Houston area with Model A's which my parent hauled us all in many a horrifically hot 4th of July parades, have been on the GreatRace several times as we drove through the 100+ degree desert in the daytime with Model A's, ...and I have been around Model A's all of my 50 years of existance on this planet, and I have NEVER seen a circumstance yet where even a higher horsepowered Model A/B engine could not stay cool with a 2 blade original (or original appearing) fan and a decent radiator. I will admit that my father sometimes used the typical 4 blade fan back in the 60's & 70's simply because they were plentiful in a time when we were seeing catastrophic failures of the original type 2 blade fans, however since the availability of the aluminum 2 blade, I (like many others) have yet to see the need for these 4 & 6 blade plastic fans that don't look even remotely authentic on what we like to deem as a "restored" Model A. If someone can give me facts on why they are necessary, I would be most receptive to hearing this.

Thanks!

.

 

[skip]

"The fan has a capacity of 855 cubic feet of air per minute at 1000 RPM of engine." <--[Page designed by Jim Mason July, 2007 ]

So the-->the aluminum 2 blade<-- is your choice as being best I take it.
Thank you.

I think Marco has the cfm/rpm data on his site. And as we all know cfm over the square foot opening yields the foot velocity in fpm through the radiator.

Or the angle of the dangle is equal to the mass of the ***. In some cases the inverse applies.

" Any data on the parasitic power loss of the different fans? " Yes Bassman/NZ in the New York Blower book. Right from the three fan laws and charts. I happen not to have one of those presently.


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