6 blade fan

M

mcgarrett

Well-known member
I'm currently running a 4 blade steel fan like the ones used on the Model B vehicles. It seems to pull enough air on most days except the really hot days we have here in Texas. Does the plastic 6 blade fan sold by the parts dealers offer any better cooling or am I better off keeping the 4 blade unit?
 
Gene F,
I thought about that too. I think I may go that route instead since switching out fans can be a real pain.
 
mcgarrett said:
I'm currently running a 4 blade steel fan like the ones used on the Model B vehicles. It seems to pull enough air on most days except the really hot days we have here in Texas. Does the plastic 6 blade fan sold by the parts dealers offer any better cooling or am I better off keeping the 4 blade unit?
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do you have engine pans too. They say the two blade fan moves more air for better cooling!
 
mcgarrett said:
Gene F,
I thought about that too. I think I may go that route instead since switching out fans can be a real pain.
Click to expand...

You can try one out of cardboard and duct tape to see if that is the way you want to go. You cab\n clean the tape residue off with a paper towel, and laquer thinner from the hardware store.
 
I do have engine pans. I know where I can get my hands on a Model A shroud locally, so I think I'll get it and see what difference that makes. Thanks for all the suggestions.
 
Had a six blade plastic fan which might have been too much mass for the water pump and resulted in premature bearing failure and pump shaft damage. Maybe it was just a bad fan or pump. Put on a new pump and cast two-blade fan with no problems - even here in sweltering FL.
 
Snyders sells a nice plastic shroud that fits well and looks nice for $99.
I run them on all my A's with two blade fans, no engine pans. Do they work?
Maybe. They look good and certainly don't make it worse.

Richard
Anaheim.CA
 
If you have a “GOOD” radiator, and engine pans?

The two blade fan is all you need. Six blades could effect your water pump.

I have never had a model A over heat.

Enjoy.
 
mcgarrett said:
I'm currently running a 4 blade steel fan like the ones used on the Model B vehicles. It seems to pull enough air on most days except the really hot days we have here in Texas. Does the plastic 6 blade fan sold by the parts dealers offer any better cooling or am I better off keeping the 4 blade unit?
Click to expand...

To answer your question likely needs to know what conditions, or how you are driving your car.

Look at the frontal area of a Model-A radiator. Likely if you are driving at a speed of 20MPH or greater, the air is going to be forced thru the radiator at a greater rate than what a fan is going to pull it thru. The goal is that the radiator tubes needs to dissipate the heat into the flowing air.

The reason why a 4-blade fan was introduced was for the AA trucks that were generating excessive heat from hard pulling yet were driving at slow speeds (-think pulling a steep grade in low gear). In that case, more blades helped pull more air thru the radiator for cooling. The issue with too many blades is it can build a wall of air where the rushing wind at cruising speeds is faster than what the flatter fan blades can pull. At that point, you are impeding the cooling abilities of the radiator.
 
If you want to know about blade count efficiency, research on why airplanes went from two blades to multi-blades.

BTW, the most efficient blade is a counterweighted SINGLE blade.

Regards
Bill
 
Why not fix the problem by flushing the block and radiator?
Tests have shown that the 2 blade fan is more efficent than a 4 or 6 blade fan.


FWIW
Paul in CT
 
BRENT in 10-uh-C said:
To answer your question likely needs to know what conditions, or how you are driving your car.

Look at the frontal area of a Model-A radiator. Likely if you are driving at a speed of 20MPH or greater, the air is going to be forced thru the radiator at a greater rate than what a fan is going to pull it thru. The goal is that the radiator tubes needs to dissipate the heat into the flowing air.

The reason why a 4-blade fan was introduced was for the AA trucks that were generating excessive heat from hard pulling yet were driving at slow speeds (-think pulling a steep grade in low gear). In that case, more blades helped pull more air thru the radiator for cooling. The issue with too many blades is it can build a wall of air where the rushing wind at cruising speeds is faster than what the flatter fan blades can pull. At that point, you are impeding the cooling abilities of the radiator.
Click to expand...

Brent,
The thought did occur to me about what you said in your last paragraph referring to multiple blades actually impeding effective airflow at some point. I'm not sure that I'm having an air flow problem or a heat transfer problem but want to be sure that the fan I'm using is doing the best job. With the heat wave we had here in Texas this past summer, my REXACO temp gauge climbed into the "Danger" zone while cruising at an indicated 50 mph but never boiled over. That made me very nervous. I do have the engine pans installed. Having to idle at traffic lights doesn't give me much confidence either. My radiator doesn't appear to have any problems, but with air temps this past summer at 108 degrees + I would like to cover all the bases. I think I'm going to get a fan shroud and see if that makes any difference.
 
My reason for going to the plastic 6-blade fan was purely defensive. I had the 4-blade "Truck" fan that decided to come apart (rivets failed) and took out my radiator. After paying for a new Berg's radiator, It was just insurance.
 
Carl,
I check my fan before every drive for the reason you just mentioned. These fans are starting to show their age in ugly, disastrous ways!
 
mcgarrett said:
Brent,
The thought did occur to me about what you said in your last paragraph referring to multiple blades actually impeding effective airflow at some point. I'm not sure that I'm having an air flow problem or a heat transfer problem but want to be sure that the fan I'm using is doing the best job. With the heat wave we had here in Texas this past summer, my REXACO temp gauge climbed into the "Danger" zone while cruising at an indicated 50 mph but never boiled over. That made me very nervous. I do have the engine pans installed. Having to idle at traffic lights doesn't give me much confidence either. My radiator doesn't appear to have any problems, but with air temps this past summer at 108 degrees + I would like to cover all the bases. I think I'm going to get a fan shroud and see if that makes any difference.
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mcgarrett
I never used water wetter (there are a few diff brands out there) until this past year and the TEXAS HEAT was horrible and the days I drove after adding the water wetter the temp was always below 180. Might be something to look into.



FYI, I think there was an article in the Restorer or ??? about fan efficiency a while back that compared the 2-4-6 bladed fans.
 
As mentioned in the posts, having a clean radiator and engine block, engine pans and a 2 bladed fan should provide all that is needed to safely run your engine at elevated temperatures. Adding more fan blades will slightly consume some additional power from the 40 horses under the hood. This additional work decreases the cooling efficiency of the engine. Cruising over 35mph provides better cooling than that produced by the fan blades. It would be nice if the blades could be disconnected or declutched similar to a GM fan.
 
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