Cooling fans

[Crosley.In.AZ]

As most folks have mentioned about electric fans I will need some small electric fans.

I have found 2 basic designs...... straight type fan blades and the S shaped fan blades.  The fans are rated for various air flows...

IN real life which FAN blade design functions better?

What about motor design.

I know we have covered this stuff before...... but I don't have a memory like enjenjo.

[Dave]

As most folks have mentioned about electric fans I will need some small electric fans.

I have found 2 basic designs...... straight type fan blades and the S shaped fan blades.  The fans are rated for various air flows...

IN real life which FAN blade design functions better?

What about motor design.

I know we have covered this stuff before...... but I don't have a memory like enjenjo.

Straight blade flows more air but more noise. ............I just put a zigro 16 inch fan on a madel a and they claimed some outrageous cfm witn curved blades no less. We tried it cause it was cheap   My 32 has a spal 16 inch straight blade fan . works great but you know its there.. I dont have a problem with that at all.. The newer fans seem to have better motors that draw less amperage . I remember 25 years ago some of the 12volt fans drew 40 amps.. Now they are a lot less because of more efficent motors.
Dave

[Crosley.In.AZ]

I've looked at the zigro.  never heard of them before.

Sure is a vast amount of $ difference on them.  I've seen the same fan advertised for 40 - 70 bucks on the net, plus shipping.

[HOTRODSRJ]

I recommend either Spal, Derale or the new syclone series from Flexalite.

Buy something in excess of 20 amps.  You need the wattage to provide work to move the air. Straight vs skewed blades are not the yardstick of efficiency. Actually, skewed or curved blades are far more efficient when combined with a certain body (shroud) design.  Curved blades are certainly more quite which is the result of producing less cavitation and "straight" is a relative term in blades.

Manufacturers that claim to move more than 110cfm per amp are simply bolstering their claims. Even in the most efficient motors, blades and shroud designs can only must about 110 cfm per amp.

I can't say much about Zirgo fans, the jury is still out.

[model a vette]

Crosley- I've been somewhat confused about straight vs. curved blades. I'm running a Celebrity curved bladed fan and shroud on my roadster. The same setup was available with straight blades. The straight blades were for HD cooling. The shroud and motor look the same as the curved setup. It looks like GM thought the straight ones were better for cooling. Any opinions?

[Sean]

I have a Straight Bladed Flex-a-lite in mine now, 16" I believe. It makes some noise, but no where near as much as the Flex-a-lite "Race Fan" that I had before.

I have been running my electric fan manually because I don't need it if I'm moving down the road 30mph or faster. In town traffic though, I usually turn the fan on when the temp gauge gets to 210, and it will pull the temp back down to 180 in just 2-3 minutes.  I am pretty happy with it.

I don't remember which model mine is, but the Fan and a wiring kit was about $70

[HOTRODSRJ]

The reason that just about all OEMs choose curved bladed fans is noise. Also, curved bladed designs require less exacting specs as far as blade clearances are concerned.  Straight-blades are more finicky about this.

As I stated before the key to moving air is the design of the interaction between the shroud and blades.  On straight-bladed fans for example you have eddys off the ends that have to be controlled with the shroud clearances. This is the blades attempt to literally "throw" the air off due to centrifugal forces. Because the ends of the blades are basically open ended..... this is very inefficient.  You see airplane wings add "vertical winglets" at the end of the main wing to prevent the very same thing...only high pressure is what is pushing the air parallel to the airmovement...not centrifugal forces.  Also, many straight blades lined up in a row have a rpm limit. This is because the blade in front of the next set up a vacuum because it's following too close so to speak.  The curved models don't have nearly this disturbance because they aerdynamically fill in the void behind each blade better.  Also goe to the noise issue.

On curved bladed fans the blades are more surface area, but less of them. The "greet" the air with a more pointed angle and centrifugal force works for the efficiency of the blade all the way out.  As the air wants to be shoved out, it gets turned around in the correct direction and hardly any losses due to eddys at the ends.

FWIW, motors may be similar in size and stature and even look the same but wound differently internally.  Also manufactures tend to use the same motor enclosures over a whole plethora of lines. The key to the motors efficiency is it's load current.   You could say the same thing about a 283 cu motor and a 383 cu motor.....but there is a difference if ya know what I mean.  

Here is a picture of the famous Mark VIII fan.  It's is good as it gets with a whopping 4000+cfms at around 40amps!  This is an alteration of a curved bladed fan.  You could turn this thing around on the back of your car and have a swamp buggy!

[tommy b]

Interesting thread. Question. How do you tell how many cfm you need for a given engine displacement? I've got a 351 Windsor engine in my 51 Victoria. What size electric fan do I need?

[Glen]

SRJ....whats the mount dimensions on that Mark 8 fan?

[tomslik]

maybe another option,


http://www.maradyne.com/maradyne_mobile/products/r_fans/

don't know a * thing about them, though.

[Dirk35]

HOTRODSRJ, yes, Please tell us more about that Mark VIII fan.

And possibly where to order it that displays its demsions.

[slocrow]

BTTT as I'm also interested in more info on the fan......Frank

[Dirk35]

BTT

Id like to know more about that fan, like who makes it, what are deminsions..................... How to order one.

[Crosley.In.AZ]

I beleive the fan is an OE fan from a Mark VIII Lincoln

[old32]

By the way Tony I'm interested in how you made the room for the fan from your previous post.