PS: Rusty, thanks for the info on the gearbox. That Hirth box or something
similar sounds like a good way to go. 170 lbs is outstanding for a 100hp
engine -- could be even more with peripheral porting.

Best of luck with your Kolb project. I hope you will have some pictures
available.

Thanks Gordon. BTW, Richard Sohn's 12A single rotor is peripheral ported.

PP vs the normal side ports is a hotly contested issue on the rotary list,
and I personally believe it's not worth doing for our 7500 rpm range. I've
been told that a good porting job on 3rd gen housings will get you the same
power as PP at the same rpm. The side ports will lose big if you're going
to run up to 9000 rpm or so, but we don't. There are a number of folks who
are very committed to the PP tests, and are using smaller than "normal" PP
ports, to improve the performance at our rpms, but until some of them are
running, and can be compared to what's already out there, we won't know.

Numbers I've heard for 7500 rpm for a single rotor with side ports are
upwards of 120 HP. Since you have to have a muffler of some type, and since
turbos seem to work pretty well as mufflers, I'm planning to use a small
Garrett turbo as my muffler. It's probaby not much heavier than a muffler,
and associated pipe would be, so it's not that much of a weight penalty. If
you choose to run the boost that you could get from the turbo, it should be
closer to 180 HP. For the Kolb, this would be insane, so I'll have to limit
the rpm, and boost to keep the power down to what the airframe can handle.
Folks have used 100 HP Rotax engines on the SlingShot, so the plan would be
to not exceed that by much, unless some 912S driver needs a lesson :-)

As you may know, Mazda went to NO peripheral ports on the Renesis, which
means they took the exhaust port off the rotor housing as well. Now all
ports are on the side housings, which allows them to have no overlap, but
still have improved power. This also has the benefit of slowing the
exhaust, which helps quiet it some, as well as reducing the temp of the
exhaust. Unfortunately, the temp seems to be picked up by the cooling system
now, so there's a bit of a trade-off there.

Cheers,
Rusty