Fried Alternator

[calmlikeabomb87]

Hi,
Just bought a 1990 Miata. Got to enjoy the car for about an hour after I bought it then the charging light came on, half hour later and some beeping, the car sputters and dies. I jump it, goes for about 5 minutes and same thing. It was a brand new battery, but now its dead, went and had the alternator checked, and failed, so I installed a brand new one from Kragens. Jumped the car, started right up, let it run for 30 minutes, went around the block slowly and everything was fine, including the charging light not being on anymore. Got home, picked up my friend and went out to enjoy the last bit of sun. I accelerated pretty quick out of a turn bringing it to maybe 6k RPM's and as soon as I down shifted the charging light came on, and about 20 minutes later it sputters and dies. The car has about 135,000miles on it and whoever had it ealier in its life put in a Greddy Turbo on it, if that my have anything to do with it. So why did my brand new alternator fry with the high RPM?...Solutions? Thanks!