Firebird1984

I have just installed a new 350 crate engine (basic 350) and while I have a mechanical fan on it now, I would like to switch to an electric one. I think I can use a thermostatic switch screwed into the passenger side of the block or head to trigger it, but I am wondering what everyone thinks concerning the size of the fan. I would like to get a single fan, but I am wondering if they move enough air to actually cool the engine adequately? I think I read somewhere that you need about 3000 CFM for a small block V8 but many of the single fans are in the 1500-2000 range and would be too small. Am I stuck having to go to a dual fan? What aftermarket electric fans do you guys recommend?
Thanks!
Brad

Stekman

my 400 can get by with less than 1600 cfm. 1600-2000 is usually adequate for normal small chevies. I personally put more importance on the radiator than the fan.

foney_email

Well lets say he was running a stock radiator, what cfm electric fan would he, (also me!) need to run.

I am in the same boat. I was curious what cfm would be best. This also needs to be set up behind the rad as a puller (air toward engine), right?

If it is infront of the rad, at speed it restricts flow through the rad, right?

Not trying to hijack, I just need the same info as you. Thanks for asking the same question I was wanting to know.

Jay

Stekman

Fans can go either way, pushing through the radiator (mounted in front) or pulling through (behind). I resort back to my original post of 1600-2000 cfm. If I were to cool a factory engine, I would personally shoot for about 2000 or so. I am a big supporter of a proper fan shroud as well, as a cooling fan will pull air from the area of the least resistance, and without a good shroud, that will be from around the engine bay moreso than the cavity in front of the radiator.

Most aftermarket electric fans are usually like 1650-1750 or so, then they jump up to the 2000's. In most cases, under normal driving when the fan is actually needed is arount town, stop and go traffic. At highway speeds, the airflow over the front end is a lot higher, and yes, the fan then becomes a blockage. A real good fan that many of my track friends use is the Black Magic by Flex-a-Lite. Though it's a tad bit pricey ($200), it pulls at 2,800 cfm.

Spal is my personal choice when it comes to fans. I currently run their 16" medium duty fan, pulls at 1610 cfm. They have several more at higher cfm's that are available (towards the bottom of that list are the larger single fan styles):

http://www.kartek.com/products/all/cooling/spal.htm

coolram62

iTrader: (2)

Another factory fan to consider is from Taurus/Sable/Continental(3.8L and not the 3.0L - I don't know if it would move sufficent air but might be worth a look)).They are very close in dimensions(23"x18"x5")to the 3rd Gen radiator.It's a 2 speed fan that moves close to 3800cfm on hi.I'm leaning toward using one on my '83 as I agree with Stekman on having a shroud to have as close to even air flow thru as possible.Something the factory 3rd Gen single and dual fans lack.And the 2 speed feature could be adapted to work with the factory wiring.And you can find them in any J-yard for $45-$75.
Is anyone using one of these fans currently?

Edit:I found the wiring diagram for using the 2 speed fan also.And the 3rd fan pic is for the 3.0L motor.

Firebird1984

Thanks for the replies guys, I appreciate it. I was trying to think where I heard the 3000 CFM requirement. After a ton of thought and searching on the internet, I finally found the quote on the Perma-Cool site that states that. The only problem is that fans in that range are pretty pricy.

I have heard of the Black Magic fan and I may just check that out. At that CFM rating, it will likely be enough for my needs.

Sorry I didn't mention this, but I am running a new radiator that is 1 1/2 inches thick (original one for the 305 was 1 inch thick core) and aluminum with plastic side tanks like the OEM. It was a direct drop-in. I am not running the AC condenser in front of it, so it has a direct shot from the on-coming air. Hopefully that will help some. Again, thanks for the insights.
Brad

chesterfield

coolram,

The ultimate is the "lincoln mark viii electric fan" do a yahoo search. Internet disinformation ranges from 4000-5000cfm. Used on 4.6 v8. two speed fan.

http://www.geocities.com/smithmonte/...rkVIII_Fan.htm

If anyone is considering this fan look into the wiring needs. 10 gauge wire and high rated relays. Don't use 3rd gen factory wiring.

coolram62

iTrader: (2)

Thankyou Chesterfield for the reminder.The MK8(and Mustang)fan does move more air than the Taurus/Sable 3.8L but you definitly have to go HD like you said on all the wiring and relays.The 3.8L's fan exceeds what most of our cars need unless you have a really wild motor(turbo,supercharged,high comp).
It still baffles me the 3rd Gen factory electric fans have no shroud.Which makes a world of difference in air movement and distribution over the complete surface area of the radiator.The shroud on the belt/clutch setup is great.