Quick fan CFM question

NMEMJCM

NMEMJCM

Member
Nov 10, 2009
83
2
6
Long Beach CA
#1
Well, my electric fan is not cutting the mustard..... or keeping my car cool in traffic. I am going to put a larger one on but in the meantime, I was thinking about putting the 5 blade ford stock style fan back on. My question is, about how many cfm would you say it is? DO YOU THINK IT WILL WORK IN CALIFORNIA TRAFFIC ON A WARM DAY???? If I were to install a shroud, does it need to cover the fan blades or just get close to it? I lowered my engine (Ron Morris lowering adj. engine mounts... 1/2" lower I think) so a shroud may be out of the question as it may hit the fan, unless you guys know where I can get one AND how to modify one to work? Thanks for the input!

64.5 Coupe, 347 stroker, Griffin aluminum rad, 180 thermo, new water pump. Thanks again!
 
#2
I have the RMP motor mounts

And it never caused any fitting issues with the shroud running a manual fan (2 shouds actually from diff people).

Ideally the fan blades should be half way into the shroud entrance, this allows for maximum suction though the radiator. If you have doubts go the plastic shroud that way if you have to trim it it`ll be pretty easy.
 
#4
if you're not running a shroud with the electric fan i might start there...

I've put a summit alum. rad kit in a built 350 chevy and durring motor break in the fan cooled the motor just fine...no other fan other than the one with the kit. abd thats about a 1600 CFM fan.

so I'm wondering if 1) your fan is wired the wrong way, make sure its sucking air INTO the engine bay or 2) its just too small of a fan.

what size/CFM is the one that you have in there now?
 
#5
I have a shroud on the fan now, its a spal electric fan rated at 1350 cfm. Im confident the fan is too small. Im mostly worried about if these fans flow more air and if they will hold together at 7000 rpm. Im thinkin about a 3.5" shroud with a 5 or 6 blade fan, or whatever fan is deemed best by anyone here with experience.
 
#6
Why switch over to a mechanical? You can find thin fans in the 2.5" thick range that move 2100CFM worth of air for around $100. also, you never said what diameter the current fan is. 1350 CFM at a 16" dia is going to cool more of the core area of the rad than say 1800 CFM at a 9" dia.

another thing to make sure of is that your electric thermo-couple for the fan unit it turning on at its proper time (which would be about the same time your t-stat opens). if its not opening up untill its 220* then you're already fighting it.

this is what I've got on my new setup (which is about another 330 CFM more than a similar kit) and it keeps my 289 well under 200 at interstate driving

http://www.summitracing.com/parts/AAF-ALL30076/
 
#7
Go search for my thread on my fan. I'm running a pretty stout 347 and trust me, I've lived in So Cal and your heat/traffic have NOTHING on the heat and traffic I've put my horse through here in NW Florida and in Atlanta (it aint called Hotlanta for nothing!)
 
#8
NMEMJCM said:
I have a shroud on the fan now, its a spal electric fan rated at 1350 cfm. Im confident the fan is too small. Im mostly worried about if these fans flow more air and if they will hold together at 7000 rpm. Im thinkin about a 3.5" shroud with a 5 or 6 blade fan, or whatever fan is deemed best by anyone here with experience.
Click to expand...

1350 cfm is no where near enough to cool a stock V8. in fact it is marginal for a stock inline six. rather than go back to a mechanical fan, i would step up to a taurus electric fan. those things pull 3500cfm. you will need to step up to a 100 amp alternator, and run a relay that can handle at least 70 amps.
 
#11
What kind of thermocouple does the setup use? If it's one of those cheap things that poke into the radiator fins, that's half the problem right there. The fan being inadequate is the other half.

On thing I found interesting is that not all stock 50blade fans are created equal, especially after 40+ years. My radiator is a three-row brass and I used the stock '68 fan with a shroud and it would borderline overheat in outside temps over about 75°. I literally found a mid-'70s five-blade Ford part that has stiffer blades with more curvature. It looks otherwise identical to the old one, but works a lot better.

cd6cafe5.webp
 
#12
Wow.... good to know. I fear I have to ditch my electric set up because the distance from my rad to water pump pulley bolts is 2 7/8". I called flex a lite and they recommended a composite 400 series 17" fan (number 417). I figure a 1/2" spacer and a 3.5" shroud should do the trick (positioning the fan 1/2 wan in and out of the shroud. anyone have any experience with these fans? The tech guy said that with that set up, it should pull 2200 cfm all day at an idle. here's the link

Flex-a-lite 400 Series Economy Fan

THE STOCK FAN WAS 17" IN DIAMETER... RIGHT??? :shrug:
 
#13
I have a flex fan on mine right now. I want to switch either to electric or stock type with fan clutch.

I was thinking about getting a Taurus fan for mine, but I'm worried its too wide. I have about 3 inches max between the water pump snout and the radiator. Which Taurus fan are you guys using?
 
#14
NMEMJCM said:
Wow.... good to know. I fear I have to ditch my electric set up because the distance from my rad to water pump pulley bolts is 2 7/8". I called flex a lite and they recommended a composite 400 series 17" fan (number 417). I figure a 1/2" spacer and a 3.5" shroud should do the trick (positioning the fan 1/2 wan in and out of the shroud. anyone have any experience with these fans? The tech guy said that with that set up, it should pull 2200 cfm all day at an idle. here's the link

Flex-a-lite 400 Series Economy Fan

THE STOCK FAN WAS 17" IN DIAMETER... RIGHT??? :shrug:
Click to expand...

Hi,
I'm running a 4 row copper rad wiith the 17" flex-Lite, it's positoned within 1" of the rad surface (ideal), it's 50/50 within the shroud. My engine is a juiced up 333 and will idle for hours at 90 deg. ambients.
The key is the position of the blades relative to the rad and the containment of air flow with the shroud.
Good luck!
 
#15
35 amp alt

tx65coupe said:
I have a flex fan on mine right now. I want to switch either to electric or stock type with fan clutch.

I was thinking about getting a Taurus fan for mine, but I'm worried its too wide. I have about 3 inches max between the water pump snout and the radiator. Which Taurus fan are you guys using?
Click to expand...

So i have read some electric fans draw up to 50 amps when starting.

I dont think my 35 amp stock alt is going to work well.

Plus the CD ignition,electric fuel pump ect.

Any thoughts on this?:shrug:
 
#16
Loftus said:
So i have read some electric fans draw up to 50 amps when starting.

I dont think my 35 amp stock alt is going to work well.

Plus the CD ignition,electric fuel pump ect.

Any thoughts on this?:shrug:
Click to expand...


Hi,

Good thinking on the AMP consumption. At one point I considered an electric fan, but, having a GEN (40A), or so, I felt it would be marginal, as well. Especially, in light, of my running a CD, electric fuel pump, and a tube bass.
At the very least, you should consider a 60A unit. If you choose to go bigger, keep in mind, to check all of the associated wiring and grounds. More AMPs in a weakened dirty wiring system can reek havoc.
Good Luck!
 
#18
Loftus said:
So i have read some electric fans draw up to 50 amps when starting.

I dont think my 35 amp stock alt is going to work well.

Plus the CD ignition,electric fuel pump ect.

Any thoughts on this?:shrug:
Click to expand...

as i have pointed out in an earlier post, you will need at least a 100 amp alternator, 130 is better, and you will need a relay that can handle at least 70 amps, again 100 is better. the taurus/lincoln fan draws up to 100 amps on start up, and has a constant draw of about 65 amps(iirc).
 
#19
rbohm said:
the taurus/lincoln fan draws up to 100 amps on start up, and has a constant draw of about 65 amps(iirc).
Click to expand...

I have measured the draw on the Taurus fan and it its barely 46 amps on high start up and about 33 amp running.Ford only used a 40 amp relay for the fan and rarely had to replace the relays on Tauruses.

I have had a 40 amp relay on mine for about 4 years now.
 
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