specific fuel consumption conversion

[DaveReidUK]

pounds per hour per horsepower x kilograms/pound ÷ watts/horsepower = kilograms per hour per watt

kg/lb = 0.454
W/hp = 746

so lb/hr/hp ÷ 1643 = kg/hr/W

divide the answer by 3600 for kg/s/W, but you probably don't want to do that.