Ok... one last bit of information for those who are interested but don't understand the benefits of a pwm controller and the low impedance Ford contour fan assembly's.
I asked Brian about the characteristics of his controller and how it relates to my choice of an alternator... I've been looking at a mechman 240a alternator with 150amp idle output.. and I asked if I needed to be concerned...
His response back:
I wouldn't even even worry about it, those fans are probably going to
draw less than 5A at idle. As the cfm requirement goes down, the
efficiency of the fans goes up:
power cfm noise
100% 100% 0db
50% 79.4% -5db
25% 63.0% -10db
12.5% 50.0% -15db
6.25% 39.7% -20db
3.125% 31.5% -25db
So at 2142 cfm total, which is probably around what you'll need at an
idle, the fans will draw about 2A
On the curve, lets say you set it at 180. At 176, the fan will start at
1%, the power will progressively increase to 100% by 183
Very happy to hear that from him...
His comment of 2142cfm at 2 amps was I believe for one fan assembly which adds up to his initial comment that at idle I'll probably be drawing less than 5amps. From the threads I've read on diesel truck efans I think he's spot on on the cfm requirements at idle
The contour fan assembly's are one of the more efficient fans available that are commonly used in efan conversions and much more efficient than most aftermarket fans...