Originally Posted by aspeed

Maybe the muffler is holding them back. It could be piped timing as well if the exh timing seems anywhere near 170 degrees. Then it would need a pipe. Otherwise, yes it does seem somewhat average for a motor of that size. How are the revs with no muffler? The old .29 motors were pulling a 7 or 8" prop with a 10" pitch at 20,000 rpm. That was with very high nitro. Now the pitch is lower because of the 10% fuel mandated. I think 24,000 rpm is what they are propped at on the .21 size speed planes. Nice video .