LBZ: Factory Fan CFM Flow

[jneal]

Does anybody know the specs on a LBZ factory cooling fan? Preferably how many CFM of air it pulls? Looking at going with an electric fan on the puller and trying to figure out which electric fan to go with since they are all rated in in CFM of air. Any help would be appreciated.

 

[Big Block 88]

They do not make an electric fan that can flow the required CFM that the LBZ needs. You can supplement your cutch fan with an electric. But if you do ay towing then you will need your Mech fan.

 

[juddski88]

theres really no room to supplement, a few are running flexalite with good luck, and several are running taurus fans which is what i am putting together currently as well, and they flow more than the flexalites

so far i have found 2 god fans for $20 and now i need the relays and such and i'll throw them in

 

[03 D-max]

to answer your original question the factory fan can blow upwards of 11,000 cfm at pulling rpms

 

[03 D-max]

http://www.electricfanengineering.com/index.htm

this company will make custom setups, it may be worth looking into

 

[juddski88]

IIRC the dual taurus will flow 9k

 

[ZeroGravity58]

i run the flex-a-lites and they are a good setup. Was going to go with TX's setup but he did not have controllers in. Never had any problems with them except my tranny temps are up alittle bit. But its nice not hearing the fan roar in the summer. I also dont tow with my truck just haul some stuff around.

 

[jheyob]

Dual taurus fans will probably be your best bet, never seen them setup in a dmax, but a lot of people use them for crawlers and other off road rigs with good luck

 

[Killerbee]

CFM rating from manufacturers have no element of reality, they are free flow numbers, spec'd without being mounted in a resistive stack.

You will pull 2000-3000 cfm with electrics, 4000-6000 with the factory fan.

 

[carcrafter22]

I have towed a 12,000 pound trailer with my 06 using 2 ford taurus fans and never got temps over normal even in 100* heat here it Tx. I would try the taurus fans, worse case scenario you have to put your mechanical fan back on. I put alot of info about it on the place a while back but its still there. Let me know if you need any specific info about them. I have heard too many stories of the flexalites catching on fire or the motors failing for me to ever use them and the others were just too expensive. I think I have about $200 in my setup using bosch 90 amp relays and diamond plate to make a shroud for them as well as the 2 fans.

 

[duratothemax]

CFM rating from manufacturers have no element of reality, they are free flow numbers, spec'd without being mounted in a resistive stack.

You will pull 2000-3000 cfm with electrics, 4000-6000 with the factory fan.

the factory fan is a LOT more than 4,000-6,000 CFM..........

 

[jpowel29]

Recently swapped out the factory fan for a set of Flex-i-lites. The diesel ship has seen several controllers "melt" due to the fact they do not have a heat sink. We discussed using a couple of 60 amp relays but it is nice to have the controller ramp up the fans vs having them come on 100%. I am getting a spare controller and still deciding if I will use the relays.

 

[ZeroGravity58]

Recently swapped out the factory fan for a set of Flex-i-lites. The diesel ship has seen several controllers "melt" due to the fact they do not have a heat sink. We discussed using a couple of 60 amp relays but it is nice to have the controller ramp up the fans vs having them come on 100%. I am getting a spare controller and still deciding if I will use the relays.

I havent melted a controller yet...i heard the new controllers were supposed to be fixed and not melt like the old ones.....

 

[LBZ]

CFM rating from manufacturers have no element of reality, they are free flow numbers, spec'd without being mounted in a resistive stack.

You will pull 2000-3000 cfm with electrics, 4000-6000 with the factory fan.

Where did you get these figures from?

Also, the CFM rating ABSOLUTELY has an element of reality. The resistive stack as you call it does not change when you change your fan to one with a higher/lower CFM. So if you lose 2000CFM due to resistance to airflow you will lose if you switch to electrics-providing your surface area stays the same.

IMO your loss may increase with the addition of electrics due to the housings and framing that go with them that may restrict flow, but I don't believe it would be a huge increase.

 

[Killerbee]

the factory fan is a LOT more than 4,000-6,000 CFM..........

nope. not in the factory configuration.

 

[JOHNBOY]

I have a Derale 4000 CFM dual universal setup on my puller. Works dandy. I would not tow cross county with it but for a competition truck works great.

 

[Killerbee]

That 4000 rating is in no way moving 4000 cfm, though I realize that is not important to you. Throughput in our real world configuration will be under half that. Throughput is defined as the amount of air actually moved from the front face of the stack, under fan locomotion only. Good shrouding is a key element to maxing out throughput.

 

[duratothemax]

ok KB, so why not explain it to us idiot non-engineers, what the "actual" rating of our factory fan is. Because ive been around a lot of 5,000 CFM fans and Im 100% positive the factory fan moves a buttload more air than that. Why does flex-a-lite rate their fan at 6,000 CFM or something, and give warnings about not towing heavy? Should work fine, because the factory fan moves less than 6,000 CFM right????

ben

 

[WolfLMM]

The factory fan moves more than that when its not in the stack. Put it in the stack and flow is reduced. That's the way I take what he is saying.

 

[LBZ]

The factory fan moves more than that when its not in the stack. Put it in the stack and flow is reduced. That's the way I take what he is saying.

That's the way I understand it as well and it makes sense to me.

But where did those numbers come from is the question I asked. I know CFM can be calculated by using RPM and the fan's dimensions, pitch, etc to figure how much it moves freely, but how does one do the math to determine what the resistance of the stack is to figure the actual CFM.

Also, I believe the actual number would be different between the Chevy and GMC trucks due to the different grille opening design no?