<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">You mean there is another one behind the radiator that you can't see from the front? And that's the one that roars? </div></BLOCKQUOTE>
YES, Max49. The intermittent ROAR you hear is the main engine-driven fan, which is there to cool the water in the radiator, which cools the motor.
The two electric fans are primarily there to aid in cooling the freon inside the A/C condensor. I think you will see them running anytime your motor has reached operating temp. AND the A/C is on. Those little babies could not blow enough air thru your radiator to cool off that big 8.1 L engine.
I'll defer to DriVer for the answer to your "total fans" question, as I am not that good at math