xyz 26s turns a 16x10 apc at 8300 rpm.18x8 at 7000rpmIuse a 16x8 @ 8600rpm for myyak54 8lb 10oz plane and it flies stright up almost as fast as it flies forward. I fly for 15 mins on a 8 oz tank, but i fly slow and lots of hovering and harrier.mine weighed in at 930g thats just under 33ozwith ignition, muffler, spark plug, mounting hardware including screws prop hub stand offs. Engine only wieght is 700 grams. Check out the video on youtube. The engine is vary new and a bit hard to get, but you can get the 26hp at hobbyking.com wich is vary simular in performance but it takes a bit longer to break in because its a rotory valve and its abit heavier.

After that the best 30cc gas engine on the market is teh DLE 30 about 1050 grams with ignition hardware, and muffler. It claims to swing a 20x8 i dont have much experience with the engine, but i do own a dle 55 and the claims they make are dead on.

http://www.youtube.com/watch?v=vLuxYtEx7qI