Electric Fan Application?

I'm new and have a 64 Impala i'm workin on. She has a 454 w/ an estimated 450HP. She hasn't been started or dynoed but desktop dynoed ( I know not accurate)!

I live in Nebraska where it's HOT during the summer (90-100*). I'm going to use my factory radiator that has been recored and cleaned to start out. If need be I'll get an aluminum if the fan doesn't work well.

What I need to know is what kind and how many cfm fan do I need? People tell me I need a 16" 3000cfm fan. I've also been told about the Black Magic Flex fan that puts out 2800cfm and has a shroud.

What do you guys think about fans and cfm for my application?

Thanks Pat!

Use the biggest full fan that will fit with the highest CFM's and it is a must to use a shroud. I think it is a pretty wide radiator if my memory serves and you could use dual's as well. Stick with Spal fans. I have been fighting this whole cooling thing and after all the research, Spal makes the best fan.

Quote:

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Originally posted by mikec
Use the biggest full fan that will fit with the highest CFM's and it is a must to use a shroud. I think it is a pretty wide radiator if my memory serves and you could use dual's as well. Stick with Spal fans. I have been fighting this whole cooling thing and after all the research, Spal makes the best fan.

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I am using a spal dual fan, may or may not be big enough for your big block but on my 327 old corvette motor 300 hp and with the griffon aluminum radiator I have yet to see the 2 spall fans run for more then one minute and cycle off, tha is at temp close to 100 degrees. The part I like about the spall fan housing are the several flexable rubber air check valves that allow full flow of the air going through the rad at highway speed. When the fans kick in the the one way seals shut and allow the fan to do its full potential. 2700 cfm and 26 amps. Ed ke6bnl

Actually the radiator on a Impala is SMALL ...15x24" I believe.

I know a shroud is a necessity and I'm not good at fabricating things.


Hmmmmm

Quote:

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Originally posted by bigpat1802
Actually the radiator on a Impala is SMALL ...15x24" I believe.

I know a shroud is a necessity and I'm not good at fabricating things.


Hmmmmm

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Given your admitted limitations I don't understand why you're trying to reinvent the wheel. Double check that radiator size. My BB rad is 25x22, has a factory shroud, and a 17" 6 blade fan, works great. It was engineered by a high paid (relatively), professional..............................a GM factory engineer. You often see backyard designed cooling systems overheat; how often do you see properly maintained factory systems do so?

The reason is b/c I have the long water pump on there.
When I went to put on my shroud..I folded the alternator back over and it hit the shroud.

Don't get me wrong..I'd go w/ a mechanical..but I have billet serpentine pulleys and I feel that an electrical would work better in my circumstances.

Okay,
check with Year One, 800-932-7663, I know they make an electric fan/shroud set up for Chevelles, they may do Impalas too.

Mike, why not post a pic of your radiator/shroud combo, it's a beauty!

Since I am home from work I thought I would show you my spall fan and Griffen radiator combonation for may 327/300 hp motor for my 50 Ford F1 Ed ke6bnl

Here is the picture I posted of the engine in the earlier post where the radiator and shroud show pretty well. It is a PRC Radiator. Just give them the demensions and they will build it to your exact specifcations. Just be sure if you order a shroud from them that you are exactly sure where the center of the fan, either electric or mechanical needs to be or cut your own hole.
http://img67.photobucket.com/albums/...1/39Engine.jpg

That looks good Ed..I'm sure that more than enough for that engine...Loookin good!

I have seena few posts here that say that a fan shroud is a must. Well If the fan is a puller, then I would say that a shroud probably is a good idea, however, if the fan is a pusher, mounted in the front of the radiator, the shroud does more harm than good. It restricts airflow to the entire radiator when the car is in motion.

Toaster.

Yeah..I"m going to get a puller.

I've also been looking at a jeep forum where the guys are saying that the mid 90s 3.8 Ford Taurus' has a strong fan and pulls a ton of cfm.. One guy went to say that they both had the same id # however they look different and in size I believe..maybe not.

I'm going to try one and I'll let you guys know my results here in 2 wks. I couldn't find a Mark VIII anywhere

Maybe dumb question, but:
What's wrong with a pusher fan?

True, most factory setups are pullers, but that's not a complete answer...

regards
Jay

Agreed that a pusher is not the optimum setup. But, when there no room for a puller, as in my '34, the pusher is the only option. if a pusher is used, definately there should be no shroud and the fan blades and housing need to be as unrestrictive as possible.
Toaster.

Oh, yeah... The size of the radiator has a lot to do with it too. if your radiator is just barely doing the job now, a pusher fan will make things worse. I always try to run more radiator than I need. (for those long afternoons stuck on the freeway ;-)
Toaster.

Quote:

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Originally posted by jaymaechtlen
Maybe dumb question, but:
What's wrong with a pusher fan?

True, most factory setups are pullers, but that's not a complete answer...

regards
Jay

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Driving down the road any fan is of little benefit as "ram air flow" is moving through the radiator to carry away the heat removed from the coolant (assuming sufficient grille opening, no debris, sufficient core size, etc). Putting a pusher fan in front of the core is an obstruction to that air flow at speed. The pusher fan may have some benefit at low/no speed as it will keep some air flowing to carry away heat. Mounting the fan, electrical or mechanical, behind the radiator (puller type) has the advantage of not restricting ram air at speed, and providing flow at low/no speed. You'll see some shrouds that have "flapper doors" made of "rubber" sheet stock that will open when the ram air effect is in place, and the draw of the fan will keep them closed when the vehicle is stopped or moving slowly.

Some additional thoughts on shrouds. Years ago GM cars had shrouds that were pretty much just a cylinder of metal about an inch larger than the fan (or vice versa depending on your perspective). They made the flow caused by the fan effective only within that circle, and the rest of the core was exposed. Good idea for the ram air flow, but, depending on the cooling demand, could be marginal for low speed. With the advent of A/C becoming nearly standard equipment, that type of system wouldn't work anymore. That's why a "proper" shroud is now considered to be one that covers the entire core surface, and the largest possible fan (s) used to draw the most air through. Of course cfm is important too as not all 16" (for example) fans are equal. There are other factors too, not just core size, # rows of tubes, core material. There's also how well the engine compartment vents (all that rammed or pulled air needs to get out), and how the engine is set up (bare headers/coated headers, rich or lean, iron/aluminum heads, etc. etc. etc.)

ok-
Now:
all the air that enters the core must also exit it.
Why would it make any difference whether the fan is obstructing the front or the back of the radiator core?
It will still cover the same surface area, right?

OR: does the condition of the air coming off the fan blades make a difference? When in front, the air will no longer be travelling straight into the core, but at some kind of angle coming off of the blades.
When in the back of a radiator core, the fan gets straight-flowing air, and nothing behind it cares WHICH way the air is flowing coming out of the fan?

However, the above explanation/hypothesis only matters when the fan is running, not when it is of and the system is working on ram air.

???
regards
Jay

With an object in front of the radiator the air will "pile up", thus reducing flow. The air being fluid will seek the path of least resistance. This leads to another "theory" in cooling system design. If you look at a factory system there will be some method/effort made to seal around the core support so that all air will be induced to flow through the core, rather than seek another path. Often when folks modify a car they don't take this into consideration and remove "things" (seals, baffles, whatever) giving the air a chance to go over, under, or around the radiator.

A secondary adantage of the shroud on the back is that it creates a venturi effect (admittedly minor) that accelerates the flow of the air away from the core.

I have used both types (push and pull) and the pull works so much better. As a matter of fact, I tested the two simply by putting my hand in front or behind the radiator and the pulling action of the puller fan created a very noticable draft as opposed to the push. It just works that much better.

Don't question it any longer and get the puller type and you'll be happy.

The car I have now was set up with a push type and I'm definitely yanking that and installing a puller.