Here are just some thoughts. OK due to the historically never ending horsepower creep I see many perhaps most who have 'Sixty' size airpanes actually installing typically upwards of ,91's these days.

Now recently four of us have purchased the new OS 15cc gasser, I have not installed mine yet and I am trying it for an entirely different purpose than the other three that I will get to in a minute. The other three all formerly used .91 four strokes of various types and the airplanes are actually Senior Cadets! Huh, ya you see I run a series of pylon races just for two classes of senior cadet and the gold class limit is 1.00 ci or 15cc.

Well while the engine has proven to be superb its actually working out to be less power and a slower airplane.

Now when one wants to place a 10cc engine in a Sixty size? Well I got a problem and feel many will be disappointed perhaps just me but I personally would only consider a 10cc as a replacement for a 'Forty' size engine, that is when the goals are what most people want them for. Back to my 15cc OS the purpose is not speed or blazing performance but fuel economy and the need to lift a gallon of fuel off the water with one of my cross country airplanes.

John