Jake,

You may as well throw all this horsepower stuff out the window? It means very little to anyone that plays around with engines all the time. Most often, the figures are at rpm's that are not practical for use. To get 16,000 rpm from a Tower 46 would be to run a 8-6 prop on it and your static thrust would be zilch. My father-in-law always said that figures don't lie but liers figure. The HP ratings are just advertising hype.

The only real comparison would be to run 6 each of all these engines with the same prop (11-6) and fuel on the same day and pick the best runs of each brand...

Right now, the most powerful engine seems to be the AX. All of the ball bearing type engines you listed are very close in power. You would be very happy with any of them. The OS-LA series is not ball bearing and has much less power than the other engines. It is more of an engine for a smaller trainer or a very light weight special purpose plane.

Enjoy,

Jim