Okay, here's the deal on racers and drag cars using the electrical fans. THEY RUN OFF THE BATTERIES. Yep, that's right. When your sponsor dollars count on a win you eliminate EVERY bit of parasitic drag you can on the engine. Track races and drags have short demands on batteries for accessory power and they can be swapped very quickly in the pits or paddock. Now I know you're going to point out rallys and such as that. Well, rally vehicles and related run in production classes that often don't allow too much modification to the auxiliary systems. For example, I'm building a Group N car and pretty much if it came with an electrical fan that ran from the mains then that's what you're stuck with. Plus when you can't pit or find your support vehicle (and crew!), carrying a load of batteries if allowed kind of negates the parasitc reduction on the engine. Then you're in less of two evils territory. That's why you see so much induction and extraction cooling since high speed aerodynamics aren't that critical when you're slogging through the woods.

There is a formula for calculating mechanical load on an alternator and I know it involves capacity of the alternator, ratio of drive (alternator pulley to drive pulley) and current load (or average). If I can find it in one of my works manuals I'll post it. Somebody wouldn't have come up with the "underdrive" pulley if it didn't make a difference!