How many CFM needed for electric fan?

SadbutTrue · Dec 3, 2012

Did a serpentine swap and need a new fan. Figure I might as well go electric since space is somewhat constrained.

How many CFM do I need? I'd assume more is better but are there any fans to avoid? Setup as pusher or puller?

SadbutTrue · Dec 3, 2012

Is it worth running a small pusher fan outside, maybe switched so I can just flip it on when its hot?

iskwezm · Dec 3, 2012

if you get the right fan that covers more of the core, a pusher is not needed. I used to have a 16" pusher and a 16" puller, then switched to the Taurus fan with a shroud.It covers about 95% of the core and will suck a sheet of paper and stick it to the grill. Stay awar from Zirgo, their CFM is over rated. Derale or Spal are good fans.

SadbutTrue · Dec 3, 2012

i'm surprised at the amp ratings on some of these fans.. 20-50 amps (!) my home a/c doesn't take that much.

I am swapping to a 3g alternator.. not sure if its an 85 or 130amp model (whatever the divisions are). I'm also planning on running a stereo. Will this create problems?

mtaqua · Dec 3, 2012

I used a shaved Mark VIII, works well. The Taurus is a better fit.

rbohm · Dec 3, 2012

if you are going to use an aftermarket fan, then you need at least 2800cfm to cool a mild V8. the taurus or lincoln fans pull much more than that, so they are the best bet.

SadbutTrue · Dec 4, 2012

is there a place to get one of these fans... without going to a junkyard? i went to one for most of the rest of my 3g swap and it was... well, expensive adn miserable. and i ahve a feeling when I fire everything up half of it won't work. Summit has replacement Taurus fans for like $60, but they're not OEM (thinking about it those could have just been the pusher fans... i know my 80s caddy had a pusher in addition to the main one)..

65FBE2 · Dec 4, 2012

Are going with electric only? I had good luck with a flex fan motor driven and a small pusher set up on a thermostatic switch. Cooled my 347 just fine. Had a northern alum rad. Otherwise just make sure you have a good shroud and use a puller. Air flow through the rad is most important. 2000 plus cfm will do no good if its pulling half of it from the sides.

chris66dad · Dec 4, 2012

I used a 16 inch fan from Speedway and it pulls 2500 cfm. I also went with an over sized 20 inch aluminum radiator. The 66 can idle all day in 100 degree heat with no problem.
Pics and info: http://chris66dad.tripod.com/id39.html

SadbutTrue · Dec 4, 2012

Cool (no pun intended lol). I also got an oversized Summit/northern radiator... its about 26" wide. Its their 'triple pass' variety too, supposedly a little more efficient. Had to trim battery holder for it. I'm thinking a 16" puller plus maybe a small pusher. You saying yours is good in 100 degree heat is good to hear, though I think it hits 100 where I'm at a little more often than in Benecia so I want to be sure.

Do you have a module or temp sensor hooked up or just have the fan running whenever the engine's on? I guess if you just have the one fan there's no real reason for a module.

SadbutTrue · Dec 4, 2012

65FBE2 said:
Are going with electric only? I had good luck with a flex fan motor driven and a small pusher set up on a thermostatic switch. Cooled my 347 just fine. Had a northern alum rad. Otherwise just make sure you have a good shroud and use a puller. Air flow through the rad is most important. 2000 plus cfm will do no good if its pulling half of it from the sides.

Yeah, planning on electric only. Was originally going to use a clutch fan that I picked up in the junkyard along with the serpentine setup (alternator, p/s pump, a/c compressor, etc), but there isn't enough room between the engine & radiator for those. My stock fan appears to rotate the wrong way and it was pretty lame anyway. While I'm sure your setup works, if I'm going to to bother wiring a fan I might as well reap the benefits of it and chuck the standard fan.

SadbutTrue · Dec 5, 2012

Having some issues finding a fan that will fit & do the 2500-3000 cfm I think I'll need.

I have this radiator: http://www.summitracing.com/parts/SUM-380419-3

The 'flat', finned part (i hear this is what they are talking about when they say 'core' lol) is roughly 20" tall by 19" wide. The radiator in total is 24" wide. I only have about 3 1/4" clearance between the rad and the pulley arrangement.

The best single fan I can find is this Flex one: http://www.summitracing.com/parts/flx-116

2000 CFM, and its going to *really* be tight on the thickness. Should I get that and pair it with a smaller pusher?

chris66dad · Dec 5, 2012

SadbutTrue said:
Cool (no pun intended lol). I also got an oversized Summit/northern radiator... its about 26" wide. Its their 'triple pass' variety too, supposedly a little more efficient. Had to trim battery holder for it. I'm thinking a 16" puller plus maybe a small pusher. You saying yours is good in 100 degree heat is good to hear, though I think it hits 100 where I'm at a little more often than in Benecia so I want to be sure.

Do you have a module or temp sensor hooked up or just have the fan running whenever the engine's on? I guess if you just have the one fan there's no real reason for a module.

I am running a temperature control circuit that controls a relay which provides power to the electric fan. Look on the bottom of my "Cooling" link for a schematic. http://chris66dad.tripod.com/id39.html
GEt a curved blade to cut down on noise. People mistake the fan sound for a supercharger all the time which is kind of funny.

Sicarius428 · Jan 3, 2013

puller is more efficient. Mk8 and taurus fans are great. 3G alt is almost a must. DC controler is nice because it will ramp up the fan speed as needed instead of a 2 step that they usually use and spike your electrical system... bonus is that it will regulate the temp as needed instead of waiting for it to hit a temp to kick it into high gear.
Kevin

WORTH · Jan 6, 2013

take it from a Radiator guy, use an engine driven fan, more even cooling, more cfm, no drag on electrics, no electrics to go bad.

this electric fan craze started with transverse engines, not a need for a better fan. sometimes old is good.

mtaqua · Jan 6, 2013

if you drag race, you can cool your motor between rounds or in the pits with an electric fan and pump with the motor off; can't do that with an engine driven. sometimes there is a need.

How many CFM needed for electric fan?

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