Radiator Fans Wars: Electric vs. Mechanical or Both!

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snowboardonsnow said:
I had a 454 (not in my cruiser, I wish) I used the engine fan and mounted electric push on the front of the rad, one auto one manually switched. The truck would never over heat it helped so much.

If you have a good electric fan it will work great, don't buy the bs that it will limit air flow, those suckers will spin up fast at high speeds. And you mount them on the front, and where the engine fan doesnt hit/suck.

Also did this on a 350, in my 85 toyota pickup, only way to go.
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Take a look at the contour fans we are running.. at HWY speeds they do block airflow when not running. The shroud for them pretty much covers up the whole radiator and only leaves the fan holes open. It works great when the fans actually run, but they don't alow for much natural airflow while not running.

So the question on whether or not to have the fan in the shroud seems like a no brainer to me.. if the fan you are using came out of a truck that had it completly in the shroud, why not simply duplicate? They did do it that way for a reason in the original application.. I know that there are fans out there that are designed to work outside of a shroud (the bimmer mentioned above may be one), but the one that I have off of a 2003 tahoe that I am going to install definitly is not one of them. Take a look at the electric fans, they are all "in the shroud" Even the ones you can buy anywhere tack onto the radiator run the fan itself in a small shroud.

for the most part, without beind stuck in shrouds, these fans with high angle blades work more like centrifical pumps and pull air from anywhere and just sling it out. They need a shroud in order to efficiently pull air past them and act like screws. You can easily feel the difference in airflow between an unshrouded fan and a shrouded one. just stick your hand behind it. Have you guys ever actually done that? It's pretty substantial.
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I'm coming to this thread late but... I've been running a dual contour fan on my built 2FE for a couple of years. I've also found, and posted, that in 90+ degree temps with the A/C on, loaded down, climbing hills... that my engine temp would climb out of control. Normally cooling is not a problem but when worked hard in high heat it could not keep up. This is with a Ron Davis aluminum radiator. This is unacceptable for me.

Some speculated that it was my 180 degree tstat, which turned out to be a valid concern once I pulled it and compared the size of the aftermarket 180 tstat to OEM. I've since gone back to stock and the cooling is definitely different - OEM is a much more sophisticated design. The temp is higher but the fan seems to work less in general (I've got a variable speed DCC controller with an indicator light to tell me if the fan is running and how hard).

However just changing the tstat doesn't give me much peace of mind. Going back to a mechanical fan isn't an option - there is power to be had in an electric fan conversion and I refuse to go backwards in power output :hillbilly: My current plan is that I'm about to drop some coin on two high power SPAL 11" fans (http://www.spalusa.com/pdf/30102157_SPEC.PDF#view=FitH).

At 0 static pressure these bad boys pull almost 2500cfm each. The typically given cfm for a contour fan, which I have to assume is at 0 static pressure, is 3400cfm. That should give me ~1500 cfm more than what I've got now. The motors on the SPAL fans are bigger/deeper, but it looks like I'll still have room for a 1/2" deep custom shroud. SPAL recommends a minimum shroud depth of 1/4" and says 1/2" should be just fine.

I'm also going to go the hood vent route. I was planning on doing this any way to reduce heat soak under the hood.

Anyway, I should have the SPAL fans installed in a month or so and will report back on their performance.
 
You guys really think that heat soak under the hood would be worse at 60 mph than at idle???
 
I want vents for both scenarios. I'm not worried about heat soak at highway speeds. For that scenario I just want an alternative escape route to get the hot air out. My engine compartment is very crowded...
 
Moby said:
I'm coming to this thread late but... I've been running a dual contour fan on my built 2FE for a couple of years. I've also found, and posted, that in 90+ degree temps with the A/C on, loaded down, climbing hills... that my engine temp would climb out of control. Normally cooling is not a problem but when worked hard in high heat it could not keep up. This is with a Ron Davis aluminum radiator. This is unacceptable for me.

Some speculated that it was my 180 degree tstat, which turned out to be a valid concern once I pulled it and compared the size of the aftermarket 180 tstat to OEM. I've since gone back to stock and the cooling is definitely different - OEM is a much more sophisticated design. The temp is higher but the fan seems to work less in general (I've got a variable speed DCC controller with an indicator light to tell me if the fan is running and how hard).

However just changing the tstat doesn't give me much peace of mind. Going back to a mechanical fan isn't an option - there is power to be had in an electric fan conversion and I refuse to go backwards in power output :hillbilly: My current plan is that I'm about to drop some coin on two high power SPAL 11" fans (http://www.spalusa.com/pdf/30102157_SPEC.PDF#view=FitH).

At 0 static pressure these bad boys pull almost 2500cfm each. The typically given cfm for a contour fan, which I have to assume is at 0 static pressure, is 3400cfm. That should give me ~1500 cfm more than what I've got now. The motors on the SPAL fans are bigger/deeper, but it looks like I'll still have room for a 1/2" deep custom shroud. SPAL recommends a minimum shroud depth of 1/4" and says 1/2" should be just fine.

I'm also going to go the hood vent route. I was planning on doing this any way to reduce heat soak under the hood.

Anyway, I should have the SPAL fans installed in a month or so and will report back on their performance.
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As I've said before SPAL fans are the $hit.... I think you are running the stock I-6 right? Make sure you have room to clear the electric motors...the SPAL high performance motors are fairly large.
 
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Radiators and FANS

See thre 3 pics

Pic 1, SPAL high performance strait blade fan 16 inch version, homemade aluminum shroud / mount, with aftermarket 4 core brass radiator from Autozone.
I had this when I first isstalled my V-8, had issues with the SPAL fan controller, which has been redesigned....anyway decided to swap readiators before I really got a feel for how this works...still have the radiator for a spare.
Pic 2, different view same thing.
Pici 3, Ron Davis radiator with dual contour fans
Pic 4 & 5, same setup different view.

Since I became adverse to the fan controllers.... I went with two spal fan harnesses (very well made), and a SPAL sensor that screws into the cylinder head...in my case the passenger side cylinder head. SO what I have is either the fans are on or off....no controller.

YOu have to run some power to the fans...which means good Alt, and decent sized wires, and good connections.
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Radiators and FANS part II

See pics below.
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How about hooking the old stock carb cooling fan up backwards to vent hot air out?
 
I'm not sure if someone's already tried this, but what if you drilled out some large holes in the area of the Contour fan that is blocking the air flow? This would help bring more air into the radiator when the truck is running at speed. Does anyone know if this works or has tried it?
 
djawahir said:
I'm not sure if someone's already tried this, but what if you drilled out some large holes in the area of the Contour fan that is blocking the air flow? This would help bring more air into the radiator when the truck is running at speed. Does anyone know if this works or has tried it?
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My Rabbit diesel has something like this, only with rubber flaps over the opening. At low speed they block most of the opening. High speed air pushes them more open.
 
One of the SPAL dual fan setups has the "flapper" setup too. What looks like large rubber strips that when at speed allow air through the shroud, at low speed they close and allow the shroud to be more efficient.

I noticed something like this on a GM car one day when I was talking to my buddy at the local GM shop.
 
Elbert said:
As I've said before SPAL fans are the $hit.... I think you are running the stock I-6 right? Make sure you have room to clear the electric motors...the SPAL high performance motors are fairly large.
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I'm going with 2 of SPAL's new 11" "Extreme" fans. These won't offer as much total coverage as a 16-18" fan but they equal the Contour fan in coverage and pull a lot more cfm. The contour fan has ~1" shroud. I'm going to have to drop down to probably a little less than 1/2" to make these fans fit (they are big motors compared to the Contour's) but SPAL's tech line said that even down to 1/4" would be fine (but that 1/4" is the minimum they recommend for shroud depth).
 
Elbert said:
One of the SPAL dual fan setups has the "flapper" setup too. What looks like large rubber strips that when at speed allow air through the shroud, at low speed they close and allow the shroud to be more efficient.

I noticed something like this on a GM car one day when I was talking to my buddy at the local GM shop.
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Dodge Viper fans have this as well. I'm planning on incorporating something like this into the custom shroud I'm going to make. Piano hinges with rubber flaps.
 
ntsqd said:
Know that hot air coming out of a hood vent at speed will very likely find the vent air opening in the cowl. BT, DT.....
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Yeah, this is the main reason why I haven't done this yet. I'd like to avoid it if at all possible. If the pressure zone is OK I'd consider putting them forward at the front corners of the hood like on a Defender 90.
 
Moby said:
Dodge Viper fans have this as well. I'm planning on incorporating something like this into the custom shroud I'm going to make. Piano hinges with rubber flaps.
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I wouldn't bother with the piano hinges. Just rivet or screw the rubber to the shroud using a backing strip and let the high speed air bend it out of the way. That way there's no dirt issue with the hinges not working.
 
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