67 coupe - running Bill Mitchell SB crate dyno'd @ 547hp. I bought a Vintage Air Monster Cooler 18" electric fan that was rated @ 3700cfm. With the Vintage Air FrontRunner serpentine system, the Monster won't clear by about 1/4". So, now I am considering a thinner Spal fan, still 18" but rated @ 2700 cfm. I'm using a new US Radiator 4-core and plumbing the trans lines directly to it. I have power steering and Vintage Air also. What are your opinions on 2700cfm electric vs. direct attached steel fan? I think VA will swap the Monster out for whatever else they have but it sure is a bummer that I can't use it. 3700 cfm seemed like more than enough and 2700cfm might be right on the edge.
Thanks,

Capt. E

I have my doubts about the VA fan producing what they advertised it to be exactly, but one never knows until it's tested by independent resources.

The real yardstick for measuring a fans ability to work is amps or watts. Yours will take at least 20+amps to be able to provide the wattage needed.

The Spal line of fans are excellent and there is nothing wrong with the top of the line and I am assuming your are talking of the twin 11" fan set up.

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Steve Jack
-Concept One Pulleys and Brackets
-Engineering & Marketing Technologies
-Northern/Southern Rodder Magazine's "Jack'Stands" technical column author/originator

Steve - thanks for the info. I have 140A alternator and a completely new wiring harness (wires sized for proper amperage). The VA fan is a modified blade on an over-sized motor, ergo the clearance problem.

What I really need to know is if the Spal 2700cfm will actually provide the necessary cooling - I can cover the amp draw all day long with plenty to spare. The real problem is clearance - which completely sucks. I put a small block back in this puppy so I would have plenty of room and am getting slam-dunked by one lousy quarter inch.

Replies appreciate.

Capt. E

Question for you. I know you loose efficency but what about using the fan as a pusher?

GL

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Deon
72SS454 Clone
Website (http://home.sc.rr.com/deon)

Capt. .....the twin 11" Spals will suffice if they will fit. They are no deeper than the single model and are more efficient than a single unit, even though they are rated the same.

Mechanical fans, whether fixed or clutched, will NEVER outperform a high quality/high output electric fan, including your spal, at idle and slow speeds. You need over 2800 engine rpms for the best fixed bladed fan to produce 2700 cfms.

If you can run a clutched fan with factory shroud and use the electric as a booster pushing, this works well. Do not let anyone tell you that a mechanical fan working in conjuction with an electric up front doesn't work. I have the empiracle evidence abound.

Simply put, don't think of the fan, but just think of the areas as pressure areas. A mechanical fan simply lowers pressure behind the raditor making the electric fan produce more because it does not have to propel air into a high pressure area and visa versa. The lower the pressure on the back side, the better the flow from the fan in front. They are additive, but not linear due to the limitations of design and motor speed.

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Steve Jack
-Concept One Pulleys and Brackets
-Engineering & Marketing Technologies
-Northern/Southern Rodder Magazine's "Jack'Stands" technical column author/originator

"one never knows until it's tested by independent resources."

"Mechanical fans, whether fixed or clutched, will NEVER outperform a high quality/high output electric fan, including your spal, at idle and slow speeds. You need over 2800 engine rpms for the best fixed bladed fan to produce 2700 cfms."


Do you have any web links to refer us to? I'd like to view some of these tests for my own knowledge. I've read online that its difficult to test the CFM rating of a mechanical fan, BUT If you have the CFM ratings for various mechanical fans, it would be interesting to view their CFM versus an electric setup, many of which people seem to have problems with cooling down their v8 vehicles (except for the Mark VIII and the SPAL fans- are all the rest Junk?!).