According to the manufacturer, the net power output for an LM6000 operating at one atmosphere barometric pressure and 15°C ambient temperature is 42,406 kWe (kilowatts electric) with a net LHV heat rate of 8223 BTU/kWh, which means the thermal efficiency is 41.5% and the heat input is 102.2 MWt (megawatts thermal). The shaft power is 57,911 bhp or 43,183 kWm (kilowatt mechanical) and the generator efficiency is 98.2%. Note that HHV is a meaningless quantity in this case, as water in the exhaust is always in the vapor state. You can get curves from GE. The LM6000 is a real workhorse!