What kind of horsepower gains would I get if I switch to an electric fan?

Well, if you add one of those " chips " with it about 100 and another 125 MPG! Really, not very much, probably not enough to be noticeable.

If you are running a viscous fan then you won't notice the difference.

Well that's a difficult question for me but it will definitely make a good difference. According to my experience It will increase the power of the vehicle slightly.

If the horsepower gains only slight, what else would improve? 

If the horsepower gains only slight, what else would improve? 

Very little. If you have a viscous coupled fan then it spends most of its time free-wheeling, it only locks up when the engine gets hotter than normal, at that point you will gain (or not lose) maybe 2bhp, with a corresponding improvement in fuel consumption. The main reason for retro-fitting an electric fan is that it can be disabled when wading which prevents water being sprayed all round the engine bay.The viscous fan also wears out pretty quickly when being used as a propellor.

You may also see a gain in fuel mileage.  One item to remember is that a huge percentage gain may be barely noticeable.  2hp doesn't sound like much, but it's a 2-4% gain in power.  The same with mileage, if you gain 2.5% then (for me) it's a mighty .75 mpg, or 7 miles per tank.   When you think about it, 2.5% is a huge jump in efficiency for such a small amount of work.

The viscous fan also wears out pretty quickly when being used as a propellor.

 

So setting up the Sami like this would be out of the question??

Should have a caption " What to do with the leftovers when you crash the wings off your antique airplane. "

I installed a electric fan on my 91 sidekick .No mpg or horsepower gain, but here in MICHIGAN it help keep a constant heat in cabin.It stay about 1/2 way up on the temp gauge.