OK what we need to understand from a towing stand point is e-fans have basically 2 speeds. High and low clutch vans are varible depending on engine RPM and can create more or less CFM's depending on the need for cooling. Thus why they use them on heavy duty apps when towing. E-fans have one max CFM rating and most are not enough for towing. The newer Cummins may have e-fans to help with getting all the air over the 5097986987 different coolers and A/C stuff.
I had e-fans on my 1500 HD turbo truck and they cooled just fine and never any problems but throw 8000# behind it and its a different ball game.
E-fans are great for elminating the recipricating force of the crank. Simple math...less mass to move = more useable power.
The alt provides the electrical system with power and maintains a charge on the batt, when the amperage is exceded then the electrical system pulls power from the batt till the alt can catch back up. If you draw more power than the alt and batt can give is when you start frying alt's. Been there done that....stupid 4000 watt stereo systems pfft.
How many newer high HP cars have clutch fans? How many have e-fans?
E-fans for racing, clutch fan for towing. 
Last edited by hebdog; 10-07-2008 at 12:56 AM.
2005 Crew Cab 1500HD aka "Big Beast"
6.0L Cam'd & turbo'd **SOLD**
'03 Cummins straight piped and a programmer
"I bought a Cummins and it came with a free Dodge!"
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