Running Dual fans

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Aug 12, 2010 | 02:52 PM

Hvymtlc5

Thread Starter

Melting Slicks

Joined: Mar 2004

Posts: 3,472

Likes: 18

From: Lake Ozark, MO

Running Dual fans

I have two 1700CFM Spal fans on my BB. Do I need to run them both at the same time to keep the temperatures down (right now they both come on at 180 degrees), or can I wire one so that I can turn it on if I notice the temp coming up?

Aug 12, 2010 | 03:10 PM

damoroso

Burning Brakes

Joined: May 2008

Posts: 1,116

Likes: 5

From: Middleburg Florida

I run both mine at the same time, and have them wired to come on whenever the AC is on. Here in FL it keeps everything under 200 degrees. I'm running a 180 thermostat on the engine and a 195 for the fans. When I was running the 180 for the fans, the engine temp would hit the 180 then come down as the fans worked. To me that's a bit too cool for the engine so I went with the configuration I currently have. I also have an aluminium radiator and a high flow water pump though.

Aug 12, 2010 | 08:48 PM

69427

Tech Contributor

Joined: Jun 2004

Posts: 20,905

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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.

Quote:

Originally Posted by Hvymtlc5

If one fan will cool the engine at that particular moment, it seems unnecessary to wear out the other fan, or make your alternator work twice as hard to drive both fans.

Aug 12, 2010 | 11:17 PM

RodTeq

ToolMan

Joined: Mar 2006

Posts: 71

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From: Magnolia Texas

I use this
http://cgi.ebay.com/ebaymotors/Spal-...ts_Accessories
worth the $ and gives you complete control

Aug 13, 2010 | 12:46 AM

MotorHead

Race Director

Joined: Apr 2000

Posts: 17,676

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From: Who says "Nothing is impossible" ? I've been doing nothing for years.

Quote:

Originally Posted by Hvymtlc5

I have dual 13 inch fans and have it setup so one comes on about 185 degrees. I have a simple switch in the "control" line ( low voltage ) to turn the other one on if needed or I can just leave the switch on and both come on at the same time. So far this summer I haven't had to use both fans but you never know if you are going to get stuck in a traffic jam for a long period of time on a hot day.

I also have one fan connected directly through a 200 amp battery cuttoff switch so if the controller or relay or everything goes for a u know what I can turn this switch on and get direct power from my battery to one fan with no fuses or anything to stop that one fan from working

Aug 13, 2010 | 01:49 AM

MotorHead

Race Director

Joined: Apr 2000

Posts: 17,676

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From: Who says "Nothing is impossible" ? I've been doing nothing for years.

Quote:

Originally Posted by RodTeq

I use this
http://cgi.ebay.com/ebaymotors/Spal-...ts_Accessories
worth the $ and gives you complete control

High current and high temp controllers in harsh under hood environments are at best not the most reliable electronic devices. I would talk to Tom Dewitt about this before purchasing

Aug 13, 2010 | 07:50 AM

markdtn

Le Mans Master

Joined: Aug 2003

Posts: 7,720

Likes: 12

From: Chattanooga TN

Quote:

Originally Posted by 69427

If one fan will cool the engine at that particular moment, it seems unnecessary to wear out the other fan, or make your alternator work twice as hard to drive both fans.

I would stage them a bit so the second comes on at a higher temperature. This should also help with less cycling, which should help the motors and relays last longer.