Wow, an old thread that I had forgotten about. SGM in Southern California were selling what they referred to as factory modded .45 size engines. All that was is them shot peening the crank after cutting a flute into the counterbalance. That flute was just a cutout that cleaned up the pathway of the incoming fuel/air as it exited the back of the crank.

The blue airplane with the pink trim did work out for me quite well. The final configuration was a 9" header that was made from 7/8" tubing along with a full length Macs muffled pipe. I reworked the head to allow 20% nitro and fit a 13mm carb from a Picco .80 DF engine. On the ground and off the pipe the engine would spin an APC 11x11 at 12K. Once in the air it would unload and come onto the pipe and it was like someone hit the NOS button. I won a local season championship with that engine and airplane combo. The engine was identified as a Rossi 2x3 long stroke. Eventually I had to jump to the YS 115 to remain competitive.