i use a 1/3 HP 120 volts ac 50 to 8 amp motor. sometimes you can find these motors on squirl cage fans in old shops, most places that sell pulleys sell them. here where i live a good motor is 100 bucks a pop.
1/3 HP is very weak, but it gets the job done. i prefere atleast a 1 horse or even bigger, the rpms of my motor is 3500 rpms, but if your motor is 1800 rpm's you might can use a big pulley down to a small pulley to gain 3k at the alternator.
