[71 T/A]

I'm thinking of installing a 16" electric fan in my 71 T/A to keep the temps down when the a/c is on and the car's idling. Has anyone used one with good results?

[71 T/A]

I'm thinking of installing a 16" electric fan in my 71 T/A to keep the temps down when the a/c is on and the car's idling. Has anyone used one with good results?

[Brian Baker]

No, they don't. They don't work well at all. That's why 3 out of 4 new cars built have them.

[David Jones]

Hmmmmmmmmm. I thought that most new cars had electric fans for another reason. Front wheel drive. My truck has a good ole engine driven fan. Works fine. 71 T/A, how is your car set up? Does it overheat?

[71 T/A]

David, car runs 160 without air on, 230 with air on idling for a few minutes. It has a 7-blade stock fan with new clutch.

[David Jones]

T/A, Have you tried a 180 degree thermostat? What ratio water to anti freeze mixture do you have? In Florida you don't need much anti-freeze. Is your lower hose collapsing? Do you have a fan shroud and is the fan positioned correctly in it? Is the radiator clean, inside and out? A good 14-16lb pressure cap on the radiator?

[71 T/A]

David,
Radiator is very clean inside and out. I'm running a high flow 160 thermostat and not switching to a 180. Fan is positioned half way in shroud. I run a 50/50 mix of water and antifreeze. I tried 75% water and it made no difference. I think a big electric fan is the answer.

[RAJ7395]

I removed the mechanical fan and shroud on my 73 Z-28 and installed one big electric fan (can't remember the exact diameter). This approach didn't work well at all. When you stick a circular electric fan on the rectangular surface of the radiator, you get good air flow under the fan but none on the portion outside the fan diameter (unless your moving forward and get the the ram air effect). Therefore the net effect is a loss in cooling at low speeds.

I solved the low speed cooling problem by opting for a dual electric fan with an intergral fan shroud. This pulled air through the entire surface of the radiator and dramatically lowered my coolant temps.

Another thing to consider is how your going to switch the fans on. I tried to wire the fan to a simple back lit switch. Lets just say that the switch melted due to the large fan current draw and made a mess. I wanted to keep the fan power wires as short as possible so I ended up installing a relay on the radiator support. For the fan power circuit, battery power was routed from the battery cable thru a fuse to the switched portion of the relay. Switched fan power then goes to fans and to a good frame ground.

For the relay switching portion of the circuit, you have some options. I chose to install a back lit rocker switch in parrallel with a radiator temp sensor. That way I could flip the switch and turn on the fan or let the temp sensor turn it on automatically. For this setup, run power out of the fuse box and to a splice. The splice has three wires in. One wire is from the power source, one goes to the rocker switch, and the last one goes to the temp sensor. After the switch and sensor, splice the two wires back together and run them into the relay control terminal. You'll need to hook up the relay control ground wire to a good ground and you should be ready to go.

Their are quite a few different temp sensors to choose from. I tried the probe style that pushes through the radiator core and it didn't ever work. I ended up getting one that screwed in to my thermostat housing and it worked great.

Just my $.02

[71 T/A]

Raj,
What make was your dual fan setup - Flexalite?

[RAJ7395]

I'm pretty sure it was a dual 12" flex-a-lite setup but I'm not positive. I'd measure the surface area of the radiator before buying anything to insure that it will fit. I did this swap back in early 1996 and sold the car late in 1997 so it's been a while. I had about 2 years on the fan setup with no overheating. The car had a 10:1 compression ratio .030 over 350 with a four core radiator, an automatic tranny with a 2000 RPM stall speed converter, a high volume water pump, 160 degree stat, 50/50 mixture, and 3.73 posi rear end.

The fans drew a lot of power so i had to step up my alternator and battery size to accomidate them. Of course running my 12" subs, amps, eq, cd changer, head unit, 10 speakers, lights, defogger, rear window defogger, windshield wipers, and the fans was really pushing it.

There are four things that effect the heat transfer from radiator to the air. Temperature difference between the coolant and the cooling air, mass flow of the air and water, the heat transfer coefficients of the air, water, and radiator (metal and paint), and the surface areas . If you want a more efficient cooling system, you either raise the water temperature to get a higher temperature difference (not a good choice due to its impact on performance, oil degradation, etc.), increase the mass flow of the air or water (high volume water pump bigger/multiple fans), or increase the themal conductivity of the air (impossible as you can't control humidity), water (use a different mixture or water wetter), change the radiator material (unpainted aluminum, or increase the radiators surface areas (more fins).

[ August 25, 2002, 12:30 PM: Message edited by: RAJ7395 ]

[71 T/A]

Raj,
Yeah, I used a supposed high flow water pump - FlowKooler, not any better than stock. There is a Milodon pump for Pontiacs but I have doubts that it's any better. I'm concerned about the amperage draw with the electric fans, plus I would have to use two 12 inch fand on either side of the cross brace as it has only 3 inches of clearance. The dual setup needs close to 4 inches or so, so the one with the shroud won't work.

As far as aluminum radiators, Griffin sells 1.25 inch tube radiators while everyone else only offers 1 inch tubes. They'll anodize it in black but would that cause the radiator to be less efficient?

[Malky]

My 68 Firebird with 455 overheats at idle on hot days. I have big fan (no clutch), tight fitting shroud, fan half in, new 3 core rad, etc, etc. I figure I need to move more air through rad so I am looking for a smaller water pump pulley to speed up fan, around 6" instead of the 8" that came with the original 350. It may be a cheap fix for you. The clutch will prevent the fan driving too fast at speed.

[RAJ7395]

I didn't think that anodizing a radiator would effect the efficieny so I asked the cooling performance experts at work. They confirmed that the anodizing has no effect on the radiators efficiency.