OS .52 Four Stroke

15% Nitro.
20% Oil (18% Syn. 2% Cas.)
OS F-Plug.
8 deg C./46 deg F. 71% Hum.
100' Alt.
11.5 x 6 Bolly Clubman.
OEM Muffler.
10800 RPM

Engine was running quite rich, but here is the kicker.... I made up a Pitts style single exit muffler. Without any needle adjustments I picked up an additional 700 RPM to 11500. Got to like that!

I know a lot of fella's use an APC 12x6. I tried one once, but it tended to load up the engine and found the Bolly to work much better. With the additional RPM gain I feel I can go back to the APC. The engine is now also in an aircraft which is a pound lighter in which the weight may have contributed to the overloading.


Happy Fly'n....