I got the following from my SK .90 engine with the stock muffler after about 40 oz of break in with 5% nitro PowerMaster. I used a new SuperTigre glow plug, since it was a medium heat and long, laying around.

APC 15x6 9400 rpm (1.75 hp)
MAS 13x8 10500 rpm (1.89 hp)
Zinger 13x6 11200 rpm (1.77 hp)

The horse powers are calculated using ThrustHP, just for reference. Idling was consistant around 2200 - 2300 rpm, and the midrange was quite smooth.

Is this typical? Will it improve significantly, say after a gallon or two? I'd like to see the result of other ppl who tried this engine.

I'm also interested in SK's .50 engine. I'd appreciate it if anyone tested it, even if a few years back.

- Ken