CTD NUT

Around 20,000 CFM - There is a reason it requires 20 hp at full lock!

ScienceOfSpeed

20,000 that sounds a little high

trik396

It is a HUGE fan blade.... Consider a 15" fan blade occupies a space of about 176 square inches. Now double that to a 30" fan blade. This occupies about 706 square inches. Over 4 times the surface area. Of course this doesn't take into account blade pitch and rpms. Just a for instance. Every time you double the size of a circle you quadruple it's surface area. This can account for huge cfms from our fan which I believe is in the 26"-28" size.

ScienceOfSpeed

gotcha i understand

CTD NUT

Why? Consider the input HP required by the fan at full lock....apparently, it is 22 hp at 2500 rpm.

Now, look at HP requirements for even the largest and highest output off-the-shelf dual electric fan assemblies.
They typically pull about 30 amps. 14 volts (system voltage) x 30 Amps is only 420 Watts. Consider 720 Watts = 1 HP, we have an input HP requirement of only .58 HP. So, the OEM clutch fan requires about 37 times as much power to run at full lock at 2500 rpm but only pumps out about 4 times as much flow (assuming these dual fan assemblies truly put out 5500 CFM which I doubt judging by the massive discrepancy in input power requirements). Man, it isn't even close!

IMO, the 20,000 CFM mechanical fan is much more believable than the 5500 CFM dual electric fans.

ScienceOfSpeed

yeah trik396 explained it best