I had been wanting to try the 25LA in something other than sea-level conditions for a while to convince myself that it was a repeatable phenomenon. So, between that, and offering to let Bill Calendrella fly it, I hauled it down to Tucson for the Southwest Regionals last weekend. The answer is - it's still really good!
The only change to my previous settings was to use YS 20/20 fuel - like I had been using in my RO-Jett 61 for the last few years when flying in Tucson. As per many previous discussions, I just kept adding nitro until the fuel consumption was the same as at home, and then it ran the same in the air.
The temperatures were in the upper 60's/Low 70's with little humidity and a pressure altitude of ~2200 feet (about the same as the real altitudes). I test-ran it on Saturday morning and got some RPM readings. With the YS 20/20 and no other changes I was just a *hair* down on RPM. The 50/50 point for the 4-2 break was about 13,200 RPM (compared to 13,400 RPM with 10% at sea level) and peaked at about 14,200 (compared to about 14400 at sea level). Very close to the same, just like the fuel switch on the RO-Jett.
We flew it on Sunday after the contest, and it was very, very, good. I missed the needle on a few flights to begin with. I flew it with it 4-stroking in level flight, and while it was a little soft, it was certainly flyable and had the nicest 4-2 break ever, very gentle and the same on insides and outsides. Once we got it cranked up (about 13,400 on the ground) multiple people flew it and it was just dead-nuts, flight after flight. Tons of power - on my second flight I took off straight into a wingover and did the entire pattern without completing a lap, bolo wingovers, a dozen or so square 8's with no break, never slowed down or ran out of poop. Do that with an old ST46 airplane it and just gets slower, and slower, and slower until you have to give up.
I think everybody who flew it was amazed at how good the engine worked, and what a good package it is. I know I did better triangles on my Skyray flight than I did with my real airplane. The only issue I have had is that the needle clicks are a bit too coarse, but it's so stable in flight that even if you get it a click too fast, it's still like falling off a log to fly with and you never feel rushed in the maneuvers. The fuel consumption was matched to the altitude by adding nitro, other than that, it ran about the same as it does at home.
So, I have tested it enough to convince myself that the "new" 25LA is the best of the bunch of the small engines I have tested. The others are still good, but you won't likely do better for the money. Anyone else should be able to reproduce the same effect, just LEAVE THE ENGINE ALONE, run it STRAIGHT OUT OF THE BOX WITH *NO*, repeat NO CHANGES, bolt on an APC 9-4, and you are set.
Brett