Convert Amps to Kilowatts for a generator?

I'm trying to solve a power problem and need at least 600 amps of continual power at 14 volts DC but could need over 1000 amps for intermittent 'boost'. What size generator do i need to maintain at least 600amps continuous at 14vDC? Could 1-2 high power car alternators supply this if mounted to a microturbine engine? Is it better to use AC power generation and convert it to DC in this case?