LBZ: Factory Fan CFM Flow

[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?

Bump

 

[othrgrl]

He's working on the spreadsheets guys, give him a few days - :rofl:

 

[Killerbee]

a laugh a minute.

My remarks are about the 21" fan, and yes the spreadsheet sits on my desktop, from measuring it 3-4 years ago. I don't have a measurement for the 26" so I can't reply.

 

[LBZ]

a laugh a minute.

My remarks are about the 21" fan, and yes the spreadsheet sits on my desktop, from measuring it 3-4 years ago. I don't have a measurement for the 26" so I can't reply.

Is the 21" fan on the older Dmax's and the 26" is LBZ and newer? I did not know they went to a larger fan but if this is the case that is good news for cooling for the daily driver tow vehicle but bad for parasitic hp losses-all the more reason to go electric on a strictly puller/drag truck IMO.

 

[Killerbee]

yes.

 

[dMerrell89]

So electric fans wont work for a daily driver or will they?

 

[Killerbee]

In cooler weather, you don't need a fan at all.

 

[Accelerator]

how much CFM is needed to cool a truck towing 20k GVCW

 

[Killerbee]

oh gosh, just depends on use, grade, elevation, desired speed on grade (HP required). So many variables. You are not going to get a concrete answer on this one, but I will say one thing for certain, it is not obtainable with ANY electric alternatives. You might get about half way to what you need.