Relays only vs dual controller???

[67 455 Bird ragtop]

I'll be running a dual fan setup out of a 4th gen LT1 on my 67 'Bird. These fans don't pull a lot of amps but do cool well based on other friends who run these fans. Can you just run a relay for each fan or is it necessary to run a controller ?? I know what a controller does but am curious if I really need to run one with these fans.

[Z06vet]

You'll need a relay for each fan, but they need a signal for them to turn on. Either a sensor installed in the cylinder head/radiator, or a controller, or wired to ignition source (they would run all the time), or by a adding a switch that you control inside the car. Some fan harness kits come with a sensor + the relays. There a a few ways to do it, just need to figure out how you want them set up. I got a spal dual fan wiring kit that was about $90 and comes with everything you need. Scott

[H2Ogbodies]

I build a lot of cooling systems and have a lot of electrical experience on cooling systems..I can help you figure out the best route if you want to drop me a line or PM. As stated, there are a LOT of ways to do it but you want to keep it simple AND safe.

[Flash68]

I am in the same boat here... just picked up a lightly used Be Cool radiator with dual Spals for my Camaro.... I have seen people highly recommend the Spal fan controller, which is a little over $100, but wondering if that's really necessary.

[1969CamaroRS]

Spal's controller has one relay built in, if you plan on running a second fan you need one more relay (the setup I'm running dual spal fans + controller + 1 ext relay).

[kryptik]

The Dakota Digital Fan Controller PAC-2700 works very well too, recommend you check it out. It's just over $100 and gives you all of the control and adjust-ability you'd ever want/need.

[H2Ogbodies]

With whatever controller you use, you still want to integrate a relay controlled over-ride as a backup. The Spal controllers as they have engineered it, is only reliable for use with their fans and low amperage, low CFM output pancake style fan motors and not good enough for any HO fan(s). I've since got back to the tries and true relay setup until I find a controller that suits what I want. The Dakota Digital does appear pretty nice after perusing their controller specs I must admit.

[kryptik]

Speaking of Relays, I use the Dakota Digital with a Bosch 75A Cont. Heavy Duty Relay for High Speed and the Dakota Digital supplied 70A Relay for Low Speed. Both circuits have a freewheeling diode installed to prolong relay life.

[MonzaRacer]

I use the oval GM relays, easy to replace at any local parts store like Carquest or NAPA, AC Delco sells the pigtails and these can carry 70+amp surge and carry 50-60 amps steady.
I like using one of the adjustable controls with sensing bulb placed in core fins at upper or return hose to the radiator so when hot coolant hits it it turns on first.
Second relay wire into a regualr single grounding sensor similar to the ones used in 80s-90 Fbodys, many of the computer/tuning companies have them in several on temps, I actually like using the stocks that come on in the 215 to 230 range.
Keep the engine in the 200*F range increases efficiency and reduces wear.
Team this set up up with Evans NPG+ non-aqueous propylene glycol coolant and say a 2lb to 4 lb cap and you will have near bullet proof cooling system. It is recommended to use a larger tube aluminum radiator. You can actually pick up some good ones off ebay.
The cores from Champion are the brazed not epoxied ones and while the tanks/welds may not be as pretty as the $600-$1000 units I'll keep my cash and simply polish my own and live with cosmetic defects.
Evans also sells better flowing water pumps but IF I remember right Stewart is one who makes them.
Evans makes this coolant, 375*F boiling point, no pressure, -40*F freeze point and it never actually freezes it just turns slushy but never freezes and expands like EG coolant, and with no water it never corrodes.
www.evanscooling,com

[BOBBYA312]

Is this coolant flammable?