Question on hooking up a set of dual fans!

jolambike · #1 (**permalink**) 07-25-2006, 11:05 AM

I will be installing a set of dual fans in the front of the radiator to help running the car cooler. Thoses of you running theses fans, should I tap the connection to my existing 16" electric fan? or should I run a separate switch for them?
My electric fan now comes on as soon as I reach 190 degree, plus I have a manual switch for it.
Thanks for your input.

double ugly · #2 (**permalink**) 07-25-2006, 11:25 AM

I don't think I would add another switch. Since you have an override switch, wire it in with the puller fan if you can. It will draw more amps so that's a consideration and will need a bigger fuse perhaps. . It's really nice not to have to be concerned about manually turning the fans on.
John

trularin · #3 (**permalink**) 07-25-2006, 11:45 AM

Make a fresh circuit as the increase in current draw will cause the wiring to get down right hot if not rated for the Amperage being drawn.

you can connect a line from the battery to a relay rated at 30 Amps and then pass the switched line to the dual fans. Use a switch or thermal switch to turn on the relay.

Hope this helps.

JCoop · #4 (**permalink**) 07-25-2006, 01:05 PM

You may want to consider the SPAL PWM controller.

http://www.spal-usa.com/

I have hooked it up to twin puller fans on the GT40 and it is great. You can program when the fans go on. 1 fan goes on at 175 degrees at half speed, then goes on full speed at 180, then both fans go on at 190. When the temps drop down, the reverse happens. I used the A/C signal input wire to hook up an override switch. It wasn't too difficult to wire up. I just had to read the instructions 4X.

vettestr · #5 (**permalink**) 07-25-2006, 01:22 PM

I think as the others have suggested a new circut should be used. Depending on wire gauge, length of run and of course the fan motor size your surge amperage could be in the 30 amp rang with a continious duty amperage of about 18 amps. Wire via a 30 amp relay and use 10 gauge wire on supply side for a trouble free install. I also like the manual override switch so you have option to turn on/off as desired. many kits are available with fixed or adjustable on and off set points at reasonable cost as well.

pgermond · #6 (**permalink**) 07-25-2006, 01:23 PM

For the most part it's personal choice and convience. If the existing wire is 12 or 14 gauge, you shoulldn't have any problem tapping into it, which is what I did. Also you should up the amperage for the fuse. The pusher fans don't do half the job a good puller will do, however, I do like the look of the pushers and have them installed on my car.

ByronRACE · #7 (**permalink**) 07-25-2006, 01:43 PM

I had a 16" unshrouded puller on a large radiator (33x15x4, 10 core) and the puller couldn't do the job. Rated at 2200cfm. I didn't have room for more puller fan due to the thickness of the radiator, the supercharger on the front of my engine, and the swaybar in the vicinity.

I changed to twin 14" spal pushers rated at 1730cfm each. I ran two 10ga wires to the fans and they run on independant relays. Each fan draws around 15A steady-state but spikes at power-on to 25+A, so make sure the relay contacts can handle that. Yes, you can run smaller wire...but if you want full output from the fans, don't run smaller wire. Why? The smaller the wire, the larger the series resistance of the wire and the less resulting voltage at the fans. You could run 14ga wire and it wouldn't melt...but it also wouldn't give you more than about 11V on the fan with a 14V (engine running) electrical system. You'd lose 10-20% of the fans effectiveness right off the top due to not running it at full voltage.

The twin 14" spals keep the water at 180 (thermostat temp) regardless. So, depending on your radiator geometry, twin pushers could be a whole lot better than a single puller; it certainly was for me.

B

Power Surge · #8 (**permalink**) 08-01-2006, 06:08 PM

My car has the dual pushers in front and the single aftermarket 16" on the inside. They are all wired together as far as I can tell, done by the building Shelby dealer. I have noticed that the past few times I've had the car out, it gets a smell of burning electrics, and tonight I realized it just does it with the fans on.

Time to rewire that setup.

Jamo · #9 (**permalink**) 08-01-2006, 06:45 PM

Run a new power line to the two pushers, although they can share off the new line. That new line should have it's own relay, with it's own separate power from the fuse box. The puller should already be set up this way. You can then share the switch for both the pushers and the puller with lines running to the two relays.