New OS 55 AX, 45 minutes run time. 10.5x7 Zinger break in prop, 10% Cool Power fuel, 3,500' altitude, 70 degrees F. Stock muffler w/baffle in place. 13,500 RPM.

Switched to 11-7 APC sport prop. 13,000 RPM.

Typical top quality OS product. Fires right up, excellent idle right off the bat. I bet there is a lot more power to be found here with tuned muffler/pipe, nitro, etc.

This engine replaced an OS 46 AX in a Graupner Skylark (50 size sport pattern plane) that weighs about 5.5 lbs empty. Significant performance gain! I will post more numbers as time permits.

Happy flying,
Robert