[Rerb]

1 hp ≡ 33,000 ft·lbf/min by definition
= 550 ft·lbf/s since 1 min = 60 s
= 550 × 0.3048 × 0.45359237 m·kgf/s since 1 ft = 0.3048 m and
= 76.0402249068 kgf·m/s 1 lb = 0.45359237 kg
= 76.0402249068 × 9.80665 kg·m²/s³ g = 9.80665 m/s²
= 745.69987158227022 W since 1 W ≡ 1 J/s = 1 N·m/s = 1 (kg·m/s²)·(m/s)