clutch drive fans

I would call that BS. There is power to be freed up there. And that's what it's doing. Any HP not used in turning the engine is your crank output. In this case, parasitic loss from the powertrain is a constant. So it doesnt really matter crank vs wheel hp. When you reduce loss from accessories that increase will be noticed on the dyno. Fans could use 15hp... Waterpumps do, P/S pumps REALLY do, fuel pumps take a couple hp. But for a fan to use "zero" or at least the minimal parasitic draw you need an electric one. Otherwise you are still turning it one way or another. Removing it would gain 15hp I think. But not replacing a solid with a clutch of any type. I'll never use a flex fan. Regardless of rating they DO come apart and I've seen several over the years... Blades go up thru the hood, the radiator, fenders... no way. not on anything I build.