I like to add a comments on PP.
I can only confirm what Paul is getting on PP testing. PP does work! it
is
not sensitive to port timing. It runs with carbs just the same.
Potential
improvements are mainly limited to tweeking as in any engine where there
is
not much data available to start out with. Throttle response is not a
problem, even out from a bad idle situation. It is allways smooth.
Extreme ideas such as combination  PP and side port are a totally
different
story. I tried this and I could not make it work.
Noise does not seem to be different from side ports. I am running my
tangential muffler on the test stand in AC configuration, and the noise
is
tollerable.

On fuel consumption, it is only BSFC that count, ther rest is airplane
and
settings specific.
I only wish I could have access to a real dyno soon.
The testing I do presently is for making sure the engine mods on the
weight
savings are holding up, before i go to final and flyable components.

Richard Sohn
N-2071U

I would love to hear more about your test stand.  Got any pictures?

tc

Here are some pictures I took. Some of which have been recently
uploaded Todd.

Paul Lamar