Originally Posted by
skohobopdo
Why do you cut down the stock muffler expansion chamber? I was under the impression that larger expansion chamber = more power while maintaining silencing capabilities.
It has to fit on an airplane and be light, both of which are problems with the OEM mufflers.
Originally Posted by
skohobopdo
what is it, something like at least 10 times the cylinder bore is better?
That would be 10 times the cylinder displacement. That is a recommended rule of thumb minimum for a quiet muffler, which isn't really what a large majority of model aircraft mufflers are. Along with volume you need to be tuning tube lengths and using baffles if you want to really quiet an engine down and not hurt power output too much.
Mark