After about 35 mph, your vehicle should be operating on the ram-air principle. Meaning the clutch fan is freewheeling. How much power does it take to freewheel?
Thirty five mph in third gear-drive, is how much rpm? Lets say 1300 with 3.23s. If that fan took say just 5hp to run, at 1300, the engine should certainly slow down every time the clutch engaged. What about in first gear? maybe 3500, and if the power increase was linear, now it would take 13.5hp. It seems to me if that was true, my car would speed up and slow down in cadence with the fan, as the T-clutch cycled.
I tell you what, I can't tell when my Thermostatic clutch cut's in/out except by the change in wind-noise.
I believe the results of HR's testing. but
I don't believe anyone would ever drive a big fan directly, so the tests IMO prove nothing as may regard real world applications, yet the powerloss is the first thing everyone remembers.
Put a T-clutch on there from an early 2000's Ford pick-up truck and forget about it.Mine is 14 years old and has likely got over 85,000 miles on it, and AFAIK is still working the same as it ever did,lol, namely automatically; no relays, no controller no additional wiring, no HD alternator.
BTW, electricity costs horsepower too, namely each 746 watts is rated 1 hp. But what they don't tell you is that the electricity is only about 10% efficient at the best of times, so it takes 10crank hp to make 1 electrical hp. So, if your fan draws 10 amps at 14.2 volts, that comes to 142 watts or nearly 2/10 hp but it is gonna cost you at least 10x.2=20 crank horsepower to create the electricity
The way it does this tho is over time, so your engine doesn't stall. In the meantime you burn the gas to crank the alternator to push the electrons round and round. If I learned just one thing in physics class it was that this is an expensive way to do business.