What is the truth about amperage vs CFM out of an electric fan?

[El Campo]

I am still looking for the electric fans that I am planning on putting on the 72. Problem is that there is a zillion and one options with everyone saying theirs is the best. This is STRICTLY about electric fans, do not want to get started down the mechanical fan vs electric fan discussion again. The biggest question is this: Company A says that their 16 inch fan puts out 3600 CFM while only pulling 10 amps. Company B says that their 14 inch fan puts out 1500 CFM but pulls 18 amps. Does design alone of blades etc really make that huge of a difference that a fan will put out over double the CFM and yet pull nearly half less amps? And then (I am afraid to ask this question) what is the best fan blade design?

[PGSigns]

What it all boils down to is the fan with the highest cfm and the lowest amperage is the most efficient design. So if two fans are rated at 2000 cfm and one pulls less power it has a more efficient blade and motor combination.
Jimmy

[68GMCCustom]

an efficient blade may not be quiet...something to consider. I run a dual fan system that's on like a 30 amp, or 35 amp circuit?

my truck also has a modern alternator...I think 160amp?

[El Campo]

I am wondering how realistic these CFM numbers are? I don't care if it is noisy, have 535 cubic inches running through 3 inch Flowmaster Super 44s anyhow.
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[Super73]

Originally Posted by PGSigns

What it all boils down to is the fan with the highest cfm and the lowest amperage is the most efficient design. So if two fans are rated at 2000 cfm and one pulls less power it has a more efficient blade and motor combination.
Jimmy

So you would hope...

I use to sell fans to server companies similar to Cisco. Obviously a bit smaller than car fans, but they had to move a lot of air, use as little power as possible and be able to stand up to ambient temps of 130* + for 24 hours straight. I have learned a thing or two

Originally Posted by El Campo

I am wondering how realistic these CFM numbers are?Posted via Mobile Device

That is the real question. Or even better yet, how did they come up with their amperage draw? Companies fudge advertising all the time. The other thing to consider is actuall working amperage. Are the mfg's all rating their amperage the same way? What do I mean by this?

Is one mfg giving you amperage rating based on start up where the motor pulls the most current or continous working load where it is most efficient?

Next, what tempeture are they rating that current draw at? Some mfg's will test at a lower temp because there is less loss.

Also, what voltage was it tested at?


I will have to look at the fans on my Camaro. It's either a dual 10" or 12" and they were rated at over 2000cfm each. When on, they move a LOT of air. Don't know the amperage draw though.

[Marv D]

Originally Posted by Super73

...........


Companies fudge advertising all the time..

Oh come on ,, surely you jest!! You mean I can't depend on things getting longer, stronger, and have more stamina by simply sending in $50 for some FDC un-regulated little miracle pill?????
Oh NO I am so disappointed!!!!!

That's almost like saying some of the head manufacturers lie about flow numbers!!!


all that said,, BeCool makes a really decent puller fan, but they are sure proud of it.

[Boostedbowtie]

I run fans out of a Town & Country van . Best fans I've ever had . Fits like a glove on my BeCool direct replacement radiator .

[djracer]

I would try a fan or pair of fans that Draw less current. I would make a nice aluminum or stainless shroud. The shroud and the design of the radiator are the key things. The next thing that only time will tell how long the fans will live. Make note of the brand you buy the first time and don't buy them again if they don't hold up. Do you already have the radiator for the truck?

[El Campo]

No I don't. Trying to buy one of those also. Was looking at the Griffin Extreme Cool which supports up to 800 HP with its 1.5 inch tubes. Is this necessary? Truck makes 600+.
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[Super73]

I am a big fan of OEM fans (no pun intended). 4th gen Fbody fans seem to never die and move a ton of air, as do the 3.8l ford taruas fans. If they fit in your chassis, not a bad idea.
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[djracer]

Originally Posted by El Campo

No I don't. Trying to buy one of those also. Was looking at the Griffin Extreme Cool which supports up to 800 HP with its 1.5 inch tubes. Is this necessary? Truck makes 600+.
Posted via Mobile Device

These folks are the bomb dissle They custom made my two pass radiator. http://www.fsrproducts.com/

[El Campo]

djracer can you say how much that cost you? I went on their website and it was not user friendly and could not find a price anywhere or email. Does it cool the truck well?

[djracer]

Mine was less than 300 to my door. Mine is pretty small and cools awesome. Mine doesn't have anything but two threaded bungs and a drain but the craftsmanship is the bomb.

[BigDan3131]

I have Spal Fans, they work great and last a long long time.

[dwcsr]

There is a lot more to successful cooling than advertised CFM. There is no way you will get 3600 cfm on 10 amps pulling through a 4 core aluminum radiator. I suspect the 3600 cfm @ 10 amps is a free air number and not up against a 4 core or even a 2 core.

I to am a fan of OEM cooling fans. I prefer the Taurus or Mark VIII style fans either in 2 speed or single speed depending on what you want to accomplish.

The Mark VIII style 18' fans that includes Cougar and TBird 4.6 V8 fit the 72 stock radiator nicely giving you about 85% shroud coverage. 80% is the minimum to be useful.

I use one in my stock 72
http://www.thehollisterroadcompany.com/MarkVIII.html
http://www.thehollisterroadcompany.c...VIIIrelay.html

I also have a 460 BBC with 4 1500 cfm fans in a shroud that works very well but is loud as heck. http://www.thehollisterroadcompany.c...nShroud055.jpg

I use it on a stock 58 chevy 6 cylinder radiator to cool 550 hp. This may sound odd and against the aluminum radiator sellers bible verse but I didn't know any better and it works.

Some basics you need to know before you spend a ton of cash on fans a radiators.

1. if the air can't get out of the engine compartment it can't get in through the radiator. This is usually not an issue on a 72 unless the shroud and fan openings are to small.

2. 4 core radiator flow less air than 2 core. You need to determine if you have a need for 4 core or can use a 2 core. In some instances a 2 core can cool better than a 4 core. On the NastyZ site you can read how they use a 2 core with a high CFM OEM fan to cool better than a 4 core with a aftermarket 16' electric when they drop in LT1's and LSx motors.

3. A proper shroud needs to be designed in order to allow cooling at a stop and at highway speeds. A fully shrouded radiator with a 16' fan and a 600 HP motor will over heat at highway speed and may cool nicely at idle or low speeds.

4. Look at the back of the fan. If it looks like a spider web chances are it would not allow the full CFM out of the back. OEM fans are usually very open on the back side.

5. Pusher fans are usually a problem not a help.

6. There is no real correlation of x amp equals y cfm. There are to many variables that go into it to get an hard x = y number.

I'm sure some will disagree but these are my experiences with electric fans going back 12 -15 years.