[71 T/A]

Has it ever been proven if electric fans work better for all around driving than stock mechanical fans on our classic Pontiacs?

[1967Tempest]

Not really.

On one hand there is the keeping it stock looking. SO if you have to run a mechanical fan, and have a cooling issue, you need to really get all of your ducks in a row for it to work properly.

On the other, there is a better selection of drop in and custom fan installs for the electrical route.

I have had great luck with the Mark VIII fan install. It was said that they pulled 4000 CFM. But one guy was getting Sick-and-Tired about hearing it and actually tested SPAL dual 11's Vs. The Mark VIII fan. Turns out the Mark VIII fan pulls around 2700CFM. Mine stays at around 190* in 100* heat with Mark VIII. That was with a 7lb cap. I changed to a 13lb. Should see some improvement.

If you are on the fence about which one to use, then I would say do a PRO/CON list. Both can be rather expensive. With the scale leaning heavy on the electrical side of cost..

Mechanical:
Shrouds
Fans
Spacers

Electrical:
Fans
Hardware
Charging system upgrades
Relays or controllers

HTH,
Dave

[Steve Barcak]

Originally Posted by 71 T/A

Has it ever been proven if electric fans work better for all around driving than stock mechanical fans on our classic Pontiacs?

in my extensive experience, I have not had good luck with electric fans and have not used them now since the 80s. A large 7 blade fan and heavy duty thermal clultch fan with shroud does the job and does it well.

[paint guy]

Do an internet search on"The myth of the electrical fan",an article written about changing a mechanical fan to electrical in a Mazda RX-7,but interesting reading,nonetheless.

[tqvhp]

I went with electric . One day after washing the car I drove to the store. While I was inside some water got to the relay and shorted out,and caused both of my fans to come on .50 amps each. No need to say I came out to a dead battery, real bummer.I have sense fixed the problem, and haven't had a problem sense. At least a mechanical fan wont kill your battery.

[Formula8]

Originally Posted by Steve Barcak

in my extensive experience, I have not had good luck with electric fans and have not used them now since the 80s.

I don't know how extensive the experience is as you say you stopped using them 20 years ago. Since then the Mark fan as well as the LT1 and LS1 fans have been developed. I use the LT1 fans and have absolutely no problem cooling my engine even with a less than optimum radiator. I can pretty much control the engine temp with the fan controls. Each fan is controlled by its own relay and grounding so there is redundancy. The relays and fuses are sealed in a plastic box mounted where the battery went to keep the water out.

I recall a Car Craft article where the engine driven fan consumed something like 12-15hp.

[Formula8]

Originally Posted by paint guy

Do an internet search on"The myth of the electrical fan",an article written about changing a mechanical fan to electrical in a Mazda RX-7,but interesting reading,nonetheless.

I read the article. Best part was this quote about the scientific method he made his conclusions: "745W = 62A at 12V. This is obviously already incorrect since it's ridiculous to assume that an electric fan is drawing 62A continuously. But we'll continue anyway."

[66bonne]

I love my electric fan !! That being said-I've never had an overheating problem with either of my P-Dude motors even when I ran a mechanical fan. I changed over to electric fan and water pump to eliminate parasitic drag as we like to race our Catalina.
I immediately saw the benefit of an even cooler running motor. The nice thing about electric fans is that they are not dependent upon engine RPM. The fan turns at its own speed whether you are at idle or doing 70mph down the interstate. I see you are here in Florida where we have two seasons HOT and EVEN HOTTER. My car can idle in heavy traffic on the street or in the staging lanes and the temp does not go up because of the low engine RPM - very nice.
I have a Flex-a-Lite 180 or 188. Don't remember which it is as I've had the fan in for a few years now without any problems at all, good unit.
http://www.summitracing.com/parts/FLX-180/
Thanks, Jim

[Rugratman]

I tried it all, ended up with a factory Pontiac fan, HD clutch, factory shroud. Better then anything...lol

The first time you get stuck when it's hot, you will understand.
Switch's, relay's, wires, fuses, have all let me down.

[Kenth]

Thermoclutch, fan shroud, Pontiac (GM) engineering at it´s best!
Ask Jim Hand....

http://www.dapa.org/building-a-stron...tems/#more-112

and:

http://www.grapeaperacing.com/tech/coolingsystems.pdf

[A.J.]

Swapped the electric fan for a mechanical 7 blade, high pitch with SD thermoclutch and all high temp issues went away. I actually think I have a overcooling issue instead. My electric Choke probably gets cooled down to much so it wont let go as it should.....

[ponjohn]

So what was the final outcome of the dual spals vs the mark 8?

I completely the agree the real cfm of the mark 8 fans has been
exaggerated.

I think that the electric fan is a much better choice. It has the same cooling
capacity at a stop light as it does at 70.

Couple it with an electric water pump and now you reduce heat soak after
being turned off.

[MYGOAT]

Originally Posted by Formula8

I read the article. Best part was this quote about the scientific method he made his conclusions: "745W = 62A at 12V. This is obviously already incorrect since it's ridiculous to assume that an electric fan is drawing 62A continuously. But we'll continue anyway."

Umm, I think you will find this in fact is correct. Can't argue with the law of physics.
Remember P = V x I from high school.

If you run twin 370W electric fans you will need a total of approx 62A electrical capacity if you run both fans at full power together. That's why you need to make sure your alternator is up to the job.

Some of the new fancy OE electric cooling fans use what they call PWM (pulse width modulated) motors. This is where the control system switches the fan/s on for a split second then off and back on continually (we are talking in the order of 200Hz here). By changing the frequency/duration of this switching you control the speed. Not sure if an aftermarket version is available as yet. This sytem also needs special motors as you would burn out the brushes of a normal electric motor. With these, they turn at the speed you need for the cooling amount you need. You still need to electric load protect for flat out running but in most cases they won't need to run flat out increasing electrial system life.

[1971WARBIRD]

here is some info i got a couple years ago.dyno's an engine,then runs with several different fans and you can see the difference in power they need to work.some of the mech fans use almost as little power as an electric.

http://forums.maxperformanceinc.com/...d.php?t=583958

[ponjohn]

You do not need a special motor to run a PWM controller.
You are confusing this technology with a stepper motor.

Stepper motors are multi-poled motors that respond to voltages
that are sent to the motor in a clockwise or counterclockwise rotation.

PWM controllers increase the "apparent" efficiency by pulsing the DC
source. This helps reduce the spike of electrical current by ramping
up the PWM signal.

It is very real to expect fans to draw 62 amps; I would bet the initial
spike is in excess of a 100 amps or more.

[MYGOAT]

Originally Posted by ponjohn

You do not need a special motor to run a PWM controller.
You are confusing this technology with a stepper motor.

Stepper motors are multi-poled motors that respond to voltages
that are sent to the motor in a clockwise or counterclockwise rotation.

PWM controllers increase the "apparent" efficiency by pulsing the DC
source. This helps reduce the spike of electrical current by ramping
up the PWM signal.

It is very real to expect fans to draw 62 amps; I would bet the initial
spike is in excess of a 100 amps or more.

No, they are not stepper motors. For all intent and purpose they are just normal DC motors that are either brushless or have specially designed brushes that don't arc when the motor is juiced up. If you used normal brushes they would burn out real quick with having to be switching on & off at a couple hundred Hz. The system is basically the same as your home computer fan system but on steriods.

[71 T/A]

The highest cfm rating for a dual electric fan module I have seen that will fit a Firebird or GTO is 4600. If this system doesn't work, none will.

http://www.summitracing.com/parts/FLX-295/

[ponjohn]

Originally Posted by MYGOAT

No, they are not stepper motors. For all intent and purpose they are just normal DC motors that are either brushless or have specially designed brushes that don't arc when the motor is juiced up. If you used normal brushes they would burn out real quick with having to be switching on & off at a couple hundred Hz. The system is basically the same as your home computer fan system but on steriods.

I know they're not steppers.

I would like to see more documentation to the effect of brushed motors arching
under PWM control. News to me.

[A.J.]

Originally Posted by 71 T/A

The highest cfm rating for a dual electric fan module I have seen that will fit a Firebird or GTO is 4600. If this system doesn't work, none will.

http://www.summitracing.com/parts/FLX-295/

I read somewhere that the highpitch 7 blade 19" fan with sd thermoclutch moves about 6000 cfm. Maybe I can find this info again....

[grandville455]

well i will have some drag results next sunday, will be running without the fan on down the strip, may try it with it on too. It is a race day tho so may not waste a run for that test.right now its 85 today and the car is running 185 down the highway with the fan on. when its 60-65 it doesn't even need to be turned on down the highway.So Far I like the results seems to be cooling as well as the big 18" flex fan was.Just proves that when its cool enough u don't even need a cooling fan running.