Glide Ratios

[N201MKTurbo]

One thing to keep in mind while doing these experiments, the idle speed of your engine will have a huge impact on the outcome. To do a true comparison you need to shut down the engine. I would suggest pulling the mixture to idle cutoff. The engine will relight as soon as you push it back in.

[Alan Fox]

Lets all go back to our training and remember a term called induced drag , a prop is not a screw , it is an airfoil , and while it operates it takes energy to create that lift.....Engine compression has no effect on the drag created , because it cancels out itself with expansion , so the energy consumed  is basically the friction in turning the engine , and the lift involved in the operation of the prop....And there is most certainly a transfer of heat going on...where the low pressure is on the leading of the prop , even with that engine windmilling , that prop will ice up before the rest of the plane(in icing conditions)

[Jeff_S]

Lets all go back to our training and remember a term called induced drag , a prop is not a screw , it is an airfoil , and while it operates it takes energy to create that lift.....Engine compression has no effect on the drag created , because it cancels out itself with expansion , so the energy consumed  is basically the friction in turning the engine , and the lift involved in the operation of the prop....And there is most certainly a transfer of heat going on...where the low pressure is on the leading of the prop , even with that engine windmilling , that prop will ice up before the rest of the plane(in icing conditions)

That must be engineering training you're talking about. I don't think any of my CFI's would be able to impart that level of technical knowledge in my prior training!