Nik wrote:
Ok, my instructor did a simulated engine failure in the pattern; winds
were around 20kts in the air and 13kts on the ground. Did everything
perfectly; however after we took off again, he told me to maintain 65
kts next time, and I totally disagreed.
The manual says 65 kts for best glide speed; however that is in calm
air. As a glider person, I know adding about 1/2 the headwind component
will give the greatest distance.
After the flight I pulled up the Glider Flying handbook online and it
says:

"...it is apparent that flying a faster airspeed as the headwind
increases will result in the greatest distance over the
ground. If this is done for the polar curves from many
gliders, a general rule of thumb is found, namely, add
half the headwind component to the best L/D for the
maximum distance."

But even after telling him that he said that doesn't apply to power
planes, also saying that manuals never give best glide, and there has
to be a reason for that.

Do you guys have any ideas on how I can really convince him? Any good
sources?

Thanks!
-Nik

Once the engine quits, the power plane is a glider, albeit one with a
really sucky glide ratio. As someone else pointed out, ask the
instructor what the best glide speed is if there is a headwind that
equals the POH recommended glide speed.

This is just one area in which I have come to believe that pilots with
glider experience have an edge over power pilots. I truly believe that
glider pilots have to know a lot more about their airplanes,
micro-weather, etc.

Instructors are people. Sometimes they are wrong. Since they are in
something of an authority position, there is a tendency to defend an
idea. Attempting to teach them something can be a learning
experience--the student will gain some experience in diplomacy, and
might find out that HE is wrong himself. Usually, I've found that the
instructor and student are looking at two slightly different things,
and that continuing a rational conversation will iron things out.

If not, there are lots of instructors out there. Avoid getting bent
out of shape.