When I worked for an "alternator" company, we had one customer that had us test and certify to 30000 rpm. FWIW, most auto setups are belted up about 3 to 1 so alt can be running at 15000 / 18000 rpm. Duno what they're good for now, been retired for 13 yrs at that time I wouldn't trust the oriental ones that high. wombat