RE: GP Proud Bird EF1 nitro conversion
RCG..I've never run a ringed engine for speed..so IDK nuttin about dems.
I think the idea is to check the exhaust spray for dark metallic residue. Eventually the ring takes a "seat" and the liner's pores get glazed with carmelized castor oil and burnished metal. Take off the head and inspect the progress under strong light with a jeweler's loupe.
Funny how speed works. You were probably only playing with 75% power today but I'll bet your very clean plane was traveling 95% as fast as it will later when the 100% power is available.