"Peter Dohm" wrote

I agree with your basic point. And also feel compelled to add that there
is
probably no way for anyone to know how much power the VW engine produced
in
the harvesting application--unless they metered torque, which would not be
reasonable. My supposition, just from reading the post, is that at least
half of the total fuel burned was applicable to pumping losses rather from
the work done.

Agreed

However, also have problems with the wide open throttle scenario. I also
suspect that if we were to discuss the issue at length, we would find that
we are completely in agreement; but that we insist on using different
"phraseology."

Good chance that is true. g

We really don't operate our Lycomings and Continentals at their sea level
maximum output very much of the time.

True.

My best guess is that, flying with a
fixed pitch prop on a standard day, we can achieve nearly 90 percent just
off the runway and that drops gradually to less about 75 percent by around
3000 feet msl.

Close enough, for government use! g

I will add, that when one chooses, 90% to 100% can be maintained for long
(very long) periods of time, with no other penalties expected, other than
shorter than usual TBO times being seen. This is with the supposition that
the engine is correctly cooled, and run with appropriate mixtures.

It happens, with racers, and with turbo charged engines, provided that the
owner/operator does not give a hoot about fuel burns or the reduction in
engine life. These people do not expect that their engines will have an
"extremely" high chance of immediate self destruction.

If we apply the same specific power output to a pure stock 1600cc VW as to
the smallest Lycomings, 75 percent power should equal 34 HP; which would
result in a theoretical 45 HP engine with a take-off rating that could be
as
high as 60 HP, although 55 HP is more likely--based on a 52 inch diameter
prop turning about 3600 RPM. The slightly more agressive specific output
of
the O-200 would give the 1600cc VW a rating of 48 HP which would equate to
a
75 percent level of 36 HP.

Once again, reasonable figures. I will again add that the small Lycomong is
capable of running at full output with no immediate penalty. I continue to
doubt that the VW can claim the same.

My point in all this is that a relatively slippery aircraft fitted with a
climb prop, to conform to the ancient formula of 0.2 G static thrust
measured with a fish scale, should fly safely with an auto conversion. I
remain a fan of auto conversions, but my advocacy has its limits.

I am right in line with your thoughts, as long as the reduction in power for
the VW is followed.

I too, like the auto conversion concept. I think that many can exceed the
max HP outputs (especially with a redrive, for many reasons not touched on
here; that is a different, well hashed subject) outlined here (based on HP
per cubic inch, or cc) but that some reduction in output is a rational
operational concept.
--
Jim in NC