Example:
15 horsepower (550 ft·lbf/s) = 0.000011 GW
1 horsepower (550 ft·lbf/s) = 7.456999e-7 GW | 1 GW = 1341022.089595 horsepower (550 ft·lbf/s)
Conversion Steps:
15 × (745.699871582 / 1e+9) = 0.000011185