A Plethora of Electric Fan Questions

[Anonymous]

Hey all I'm considering swapping to an electric fan setup in my '63 Falcon (with a '68 200). I've searche and read quote a bit here, but here are my remaining questions:

1. how does the fan know when to turn on and off if controlled by a sending unit? I mean, I understand the principal obviously, but does it have it's own thermostat or does it tie into the one for the gauge? Does it just get wired inline for the gauge sender? FalconParts.com sells a thermostat housing neck with a threaded hole for a sending unit just for this purpose...should I spend the money on that?

2. I've read about using a relay to turn the fan on and off: positive battery -> relay -> fan switch (right?). So what do I ask for/look for when buying this relay? Are they "standard" or do I need a relay of certain characteristics? I'd also like to include an on/off switch in the car. Does this just act like a "sending unit bypass" of sorts?

3. Since I'm not overly concerned with the few HP I can gain by eliminating the fixed fan, if I have room for it, should I leave it in place or will a good electric fan be sufficient?

thanks as always!

 

[Anonymous]

Well, there are a couple of ways to do it. The fan needs it's own temp sensor. You cannot use the one for the guage. You can use any generic relay you find in the electrical section of your parts store. I use a brand called Blazer (off-road lighting company). They are usually about $4 and will have 4 or 5 pins (pins 87 and 87a are the same connection).

Ok, you can buy a thermostatic switch to activate the relay (these type usually install into a radiator bung), OR you can buy a sensor to screw into your thermostat housing (like you mentioned) and use it to ground the relay when it reaches a set temp.

The relay pins are numbered: 30, 85, 86, 87, and 87a

85 = constant ground
86 = 12V coming from thermostatic switch
30 = Battery 12V
87 = Power to fan

or

85 = temp sensor (grounding type)
86 = 12V
30 = Battery 12V
87 = Power to fan

or

85 = temp sensor (grounding type)
86 = 12V battery
30 = ground
87 = fan ground (hook fan + direct to battery)

The manual overide swith is easy. If you run a thermostatic switch, install a switch with a 12V source and splice into the wire from the thermostatic switch going to the #86 pin on the relay. If you use a grounding temp sensor, splice into the #85 pin to the sensor and run to a good ground with your switch inline.

 

[Anonymous]

When I put the fan in my maverick, I bought a relay kit that made the whole mess a lot easier. It came with relay, temp switch, and a good portion of the wires and connectors to get you started. I can't remember what brand it was, but I see them every time I go into a parts store. The kit I got also had a lead for manual bypass or A/C bypass, even had a diode in it so the clutch wouln't come on with the fan. As far as the fixed fan, if you have a good electric fan, you should not need to use it. My 250 runs fine with a good 16 inch fan, and Tucson is a pretty harsh climate for this kind of stuff. Changing to an electric fan really does not save any horespower when it is running, because the alternator takes power to turn. The thing about electric fans is you can turn them off when you want to or when you don't need them, unlike fixed fans.

 

[rickwrench]

I've run the gamut of cooling options in the 62 Squire.
1. Stock two core rad, 195 deg T-stat, 4 blade stock fan, short nose H20pump.
Result: Overheat at idle in traffic.
2. Stock two core rad, 180 deg T-stat, 4 blade stock fan, short nose H20pump.
Result: Overheat at idle in traffic.
3. Three core rad, 180 deg T-stat, 6 blade "low profile" fan, long nose A/C H20 pump.
Result: Very hot at idle in traffic.
4. Swap to T5 transmission.
Result: Hot at idle in traffic.
5. As above, plus thermostat controlled 12 inch electric pusher, plus manual override.
Result: Warm, but still ok at idle in traffic.
6. Three core rad, two twelve inch pullers, no engine driven fan.
Result: Warm, but still ok at idle in traffic..
7. Very very large twin core aluminum crossflow radiator, 195 deg T-stat, shortnose cast impeller H20 pump, BIG six blade engine driven fan on one inch spacer, 5" H20 pulley (12% faster).
Result: 195 degrees, all the time, no matter what. This is what I'm using in both of my falcons now.
Rick(wrench)

 

[xctasy]

Gee I get sick of myself. David Vizard said it best. Even on a turbo Pinto, "twin or single fans don't provide a satisfactory wind-rush". Go to Summer Nats in Aussie, and see how many supercharged cars overheat with thermo fans. Each year guys try thermos, and they make the same mistakes. The only way thermos can work on a hi-po' Ford is if you have a shiney custom core race aluminum radiator.

Every-one likes the idea of thermo fans, but I think low number blade fans work better than 12 bladers. Seams 6 is the optimum, even though they lose power at high rpm, and are noisier. Anytime you go for few blades, you have to increase pitch, and therefore turbulence. Flex fans can also work well.

A viscious coupling fan is only okay if the coupling works. They cause vibration in many instances.

The other issue people forget it entrained air causing cavitation. There was a publicised Benett Bypass system in an articel of 1999's Hot Car, an Aussie magzine. It was used for bleading air out of the cooling system on 302 and 429 Fords. Rod Hattfiled at CRS used one.

Ford Australia used a blead valve on crossflow sixes from 1980 on- wards.

 

[Williboy]

Here's an interesting device to controll your elect fan,
http://www.centechwire.com/catalog/cooling/fc2p.shtml

Apparently you can hook it up under your dash and have full adjustability control over when your fan kicks in.

You'll still need a relay, which they sell too

 

[MercuryMarc]

To avoid overheating in slow moving parades in Reno in August I ended up using:

Large 2 row Aluminum radiator
Auxillary tranny cooler
160 Degree Thermostat
14 inch pusher electric fan
Temp sensor "T'd" into the upper radiator hose
Adjustable temp switch to activate fan
Dash light to indicate when fan is "on"
Relay for the temp sensor activation switch

Works great now.

Marc in SF
63 Comet Ragtop with 69 200 ci six
http://mercurycomet.net