dwsc,

I see the figures you posted for that engine/prop/fuel setup but what I can't tell is whether you think that RPM level is good or bad. In my experience, that RPM level is very mediochre and not really near what the .46FX is truly capable of.

Mike Connor,

What were the rpm readings you got both before and after you bolted on the Ultrathrust?

I said earlier that 14,000 rpms was pretty mediochre. I base that on long years of experience racing SIG 4-Star .40s where everyone had to use the same engine fuel and prop. The engine was a stock SuperTigre GS .40. The fuel we had to use was 15% mostly Cool Power but that might be different from race to race. The prop was a Master Airscrew 10X6(the old, wider blade configuration). Since we were pretty heavy into racing, we were taching these engines all the time. The competitive engines turned that prop from 14,800 to 15,000 RPMs. I retired many an engine that would no longer turn at least 14,800. The average engines were in the 14,500 to 14,700 range. Only once did I see an engine that would not turn well over 14,000 and that was a reallly worn out basketcase. The mufflers used were entirely stock but they were the ones which could be rotated around a short header, not the smaller ones that came out later. When Master Airscrew changed their prop configuration to a narrower blade, these engines consistently gained another 700 RPMs over what they turned the old prop with.

I guess the bottom line is that I would find it very hard to be happy with any .40 or .46 engine that would only turn a 10X6 prop at 14,000. I know that, if the engine is in good condition, the O.S. .46FX has to be capable of so much more performance than that.