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electric fan size

dirtbag7

dirtbag7

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I just got my rig up and running and I'm having some overheating issues.
its a 450 hp big block, with a be-cool aluminum radiator, flex fan, but no shroud. I fully realize that the no shroud is about 90% if not all my issues, but the fan isn't close enough to the radiator in my opinion....
I've decided to yank the flex fan and go with an electric fan, my question is how much air flow do I need? I've found all the way up to 6000 cfm, but it may or may not fit, and they are very proud of it... Help please!!!

Thanks!!!
 
I think my motor isn't anywhere near the hp, but it does get hot around here in the summer and I can watch the temp guage drop from 215F to ~185F within 10 seconds when the fans kick on. I have dual 14" electrics with a shroud and I don't believe they pull more than 3000 cfm together. I'd have to check on the number though.

I'd agree that the shroud is very important.
 
Do you plan on building a shroud for the fans, or just attaching them to the radiator with the zip-tabs? I'd measure the radiator width and height and see what fits if your attaching them with the zip-tabs.
 
OffRoadTek said:
Do you plan on building a shroud for the fans, or just attaching them to the radiator with the zip-tabs? I'd measure the radiator width and height and see what fits if your attaching them with the zip-tabs.
Click to expand...

and don't use ziptabs, make brackets. The tabs wear though the radiator over time.
 
I run this on my big block...

http://www.flex-a-lite.com/auto/html/27inch-electric.html


worth every penny...In my opinion..


I don't run flex fans off road after screwing one into my radiator during a water crossing..damn thing acted just like a boat prop and drove itself into the radiator....

Nice thing about this setup is that you can wire it to override and turn the fans on or off when you want. They are also thermostatically controlled so they ramp up and down as needed by temperature.
 
"I don't run flex fans off road after screwing one into my radiator during a water crossing..damn thing acted just like a boat prop and drove itself into the radiator....

Nice thing about this setup is that you can wire it to override and turn the fans on or off when you want. They are also thermostatically controlled so they ramp up and down as needed by temperature.[/quote]"


that's why I was looking at electric fans... The guys at Ron Davis Racing said to stay with mechanical because it pulls more at higher RPM... have you seen any overheating issues at higher RPM's? Out here in Okie it gets hot like it does there in the summer...
 
I'm only running a SBC, but needed something to keep the engine cool while towing in the summer heat. I've got two electric fans, one 16" that pulls about 2200 cfm and a 12" that is right about 1000cfm. Originally I just had the 16, but realized that another fan would be great incase the primary took a dump. Both fans are on thermostats with the 16 on an override switch and the 12 is hardwired to come on with the ignition. My fan thermostats are set at about 200* with a 185* coolant thermostat.

Here's a question for you: is your truck overheating at idle or while driving down the road? If at idle, the electrics fans could help. But if it overheats while cruising down the road, you might other issues such as water pump, plugged radiator, or bad thermostat.
 
"Here's a question for you: is your truck overheating at idle or while driving down the road? If at idle, the electrics fans could help. But if it overheats while cruising down the road, you might other issues such as water pump, plugged radiator, or bad thermostat.[/quote]"

Everything is brand new, radiator is equal to a 4 core, aluminum be-cool, new stat, new hoses, fresh block... But at idle/low speeds is when it overheats, going down the road it cools off to 180-190 quickly.. I fully believe this to be an airflow issue.
 
Sounds like it.

If you decide to go with electric fans, my suggestion is to use an adjustable thermostat and have that switch a relay to power the fans. Then you can wire the fans to the battery so there is less draw from the fuse panel. And like what I did, the thermostat can be fed from a "key-on" source so you dont have to worry about the fans still running after the truck is off. Also be sure to set the fan temp about 20* above what your coolant thermostat is to keep the fans from running all the time. Ask me how I know:rolleyes:
 
with a hesitation resmebling that of a schoolboy, I must ask, "How do you know?" lol
 
dirtbag7 said:
...I've found all the way up to 6000 cfm...
Click to expand...

A lot of these air flow ratings for electric fans are made without any obstruction to the fan. That means, no radiator fins in front of the fan to obstruct airflow.

You'll need a shroud in any case, be it for the belt-driven fan, or the electric fan. Otherwise those blades will pull air from where's the least resistance, and that is typically not through the radiator fins.
 
understandable... That's why I believe the "no-shroud" issue may be my biggest enemy right now... the other side is like what was afore mentioned about deep water crossings... I don't really like the idea of my fan deciding to drill itself into my nice radiator... I hear that's a bad idea...
 
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have you seen any overheating issues at higher RPM's? Out here in Okie it gets hot like it does there in the summer...
Click to expand...

When I drove the K5 on the street w/ the blower on it, I never had any overheating issues even in traffic in the middle of the summer...I do have my transmission plumbed to its own fan driven cooler BTW...

The complete kit comes with the controls and cab switches for the fan override.

I did break a fan blade while running in a mud pit once,,I think it was due to the amount of mud and water that was being thrown off of the 3" wide blower drive belt...It runs close to the fan shroud.

No problem getting a replacement blade though..flexalite shipped me one for free..:D
 
dirtbag7 said:
with a hesitation resmebling that of a schoolboy, I must ask, "How do you know?" lol
Click to expand...

When I first hooked up the 16" fan, I had just put in the 185* coolant t-stat. I had the fan t-stat set for the same. Originally, I thought the truck had to stay below 200* or else the fan wouldnt be able to cool the engine back down. The fan NEVER shut off. It couldnt. The engine was trying to heat up to operating temp and the fan was cooling it down.

One day when I was checking the truck before going on a long road trip, I left it running to check for leaks/issues. It had been running for about half hour and the fan was running nonstop. Thats when I noticed something smoldering. "Let me just grab this smoldering wire". Since the fan draws about 15 amps and had been running for sooo long, the wire was melting through the insulation and had grounded itself on the rad support. Needless to say I burned three fingers and my thumb.

So now the fan is set to come on at about 210* and off at 190* (I think it shuts off 20* below the on temp). This works great as the fan only runs for about 20 seconds at a time and comes on about once a minute. This is while sitting inthe driveway at idle on a summer afternoon. In traffic, it'll come on more often until you start moving above 40mph. I added the second fan simply to assist the primary. The second fan comes on about 10* above the primary, so it really only comes on in stop/go traffic or on long hills while towing.

On a side note, I added indicator lights inside the truck to know when the fans were cycling. It really helped to know what the fan is doing and what type of driving does what to the engine temp. I added the light to the fan positive feed after the relay and t-stat switch. This way if either one fails, you'll see it (or not in this case). The only problem with this is as you are going down the highway, the light will dimly glow as the fan spins from airflow. Kinda acts like a small generator and back feeds to the light. I'm sure a diode or something would fix that, but I'm not that bothered by it.
 
If you are not adverse to shopping your local wrecking yard I can not recommend the Lincoln mark VIII fan more. These fans are incredibly durable, have good availability, and move the most air of any OEM fan. The local pick-n-pull has them for $39.00.

getimage.php



These fans are even run by corvette guys. They are legendary.

Stats:
It's an 18" fan. Estimates of CFM are between 4300-5500. Draws 42amps on HIGH speed--it is a 2-speed fan. 1100 rpm in slow, 1850 rpm in fast.

here is a quick web page I found showing the install in a mustang.

http://members.tccoa.com/392bird/markviii.htm


I seriously can not get over the amount of air these things move. I used to have the flex-a-lite fan on my mustang and then installed this fan to deal with a low speed airflow problem like you are having. the difference in the airflow is night and day.

I already picked up two more of these to go in both my blazers. If you can fit it in, get one!

One word of warning, these things draw the current. If you want a fan to move air it HAS to draw current. Fans that claim 2200 CFM and only draw 15 amps are lying about the air flow. Use big wires, relays, and connectors.

Cheers,

Rufus
 
Thanks for the replies. The higher amps makes sense. I work with electric motors/controls in my "real" job and I def see the issue with a low amp, "high" volume fan...
 
"Needless to say I burned three fingers and my thumb."



I apologize for laughing at your misery... but LOL!!! Hopefully it wasn't too serious and your fingers survived to move onto the next "adventure"
 
dirtbag7 said:
"Needless to say I burned three fingers and my thumb."



I apologize for laughing at your misery... but LOL!!! Hopefully it wasn't too serious and your fingers survived to move onto the next "adventure"
Click to expand...

Oh it hurt, but I just taped 'em up and kept working.

Wasted mentioned the Windstar fans. I have read post from several members on here that swear by the Windstar setup. Supposed to be a near perfect fit, has a full shroud, and maintains a low profile. Cant beat that.
 
Junk yard fan and radiator

100_0423.jpg


This reminds me, I need to get a power steering reservoir hose

And our race car too

101_1510.jpg
 
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