ORIGINAL: av8tor1977
That's really cool!! It could be that the reason we hear, (and experience) ''grenading'' of the Ryobi when run over 7500 rpms or so is because in our airplanes when they do so it is for a much longer period of time than with boats. I have however, heard of many coming apart when run too high of an rpm. I have often thought about machining up an aluminum rod for one just for the hell of it. I think the rod is the weak link; the stamped steel crank assembly/counterweight should be no problem.
Anyway, nice project!
AV8TOR
I blew one up. It's been a few years and I haven't touched a conversion engine in a number of years. Seams the exhaust was arond 150* and we had dropped the cylinder down to .019 squish. Twin rings. Bowman rings.
It was turning 8800RPM on the ground with an 18-8 or maybe an 18-10 - again, it's been a LONG time and I'm getting a little older. It only lasted about 4 flights on a Stinger 120 after we modded it that much. Then the thing made a loud bang and the air conditioner on the front stopped spinning. Thats when the pilot started sweating.
It was fun to mod this and mod that. Then take it up to fly a few times. Back to the shop and mod this again. Grind that a little more. giggle giggle snicker snicker - let's go fly it again!! BOOM! [
] Yup, that musta been too much.
I think it may have held together if we'd used a bigger prop and slowed it down. 8800rpm was just too much for that stamped rod.