I'm with 34 on this one with the Why? But I've done some really different stuff just to do it, so I think I understand.

Problems are with the speed of the alternator. Driving it direct from the crank is going to be way to fast. Not a problem that can't be addressed but you will need some kind of a reduction to make this work. Second is coming up with a gear drive, good machine shop can do this if you can come up with some drawings of a system that works. Next your going to have to mount the alternator right next to the crank, so A workable mount needs to be designed as well.

Your question in the end is "Has anyone done this?" Man there's not much in the Hot Rodding field that hasn't been done, so yes it PROBABLY has been done. but it must not have been too succesful as you don't seem to see them around. Plan on this being a "One Off" kind of deal. Sharpen your pencil's and set down and design a system that may actually work. Then bounce the idea around some.

Roland