Just thought I would add my number to the mix.

Fuel homebrew: 5% nitro, 11% castor, 11% Coolpower blue, 73% methanol.
Altitude ~1700ft
plug OS#8

APC 11x9 ~12,150rpm

APC 12x9 (cut down to 11.5x9) ~11,000rpm

APC 12x8 (cut down to 11.5x8) ~11,550rpm

I did have some figures for an 11x10 APC but can't remember them off the top of my head. Got about 35 flights on it now (12oz tanks) and still running the same plug I ran it in on. I don't have any idle RPM figures but it's low enough for what I need.


I'm tempted to drop the oil back to 18% (9%castor, 9%coolpower) but I'm happy how it runs and it doesn't mess up my plane. Ran it in as per the manual on a test stand, full throttle alternating between rich and lean. The nip at TDC has dropped off a fair bit but I'm logging the flights (and rpm every now and then) and will see how it holds up over time. The first throttle up after taxiing to the strip is a bit gluggy, but in the air is spot on for how I fly (sport pattern).