The ABC engine has the potential for more power and requires very little break-in. It is, however, less tolerant of dirt or dust that may be ingested by the engine. Some engines are advertised as being schnuerle ported. This may result in some of the fuel passing over the piston and right on out the exhaust port. With schnuerle porting the fuel arrives from different directions and converges at the center of the cylinder which allows more fuel to be burned, hence more power.
Most newer engines use schnuerle porting.
The O.S. .91FX airplane engine is THE choice in large-scale sport power plants. It offers reliability, performance and tunability all in one. The O.S. Surpass Series features a four-stroke engine for discerning fliers. The .26 Surpass adds little weight to small models, yet features a whopping .41 horsepower at 11,000 rpm. It has a helix gear-driven camshaft on the front end and a dependable updraft carburetor in the back.