Originally posted by aptar
dwsc,
Mike Connor,
What were the rpm readings you got both before and after you bolted on the Ultrathrust?
My 46fx just after breakin would turn a 10x6 14,400 with the stock muffler. I removed the baffle and drilled out the exit and got about 14,900 with the same prop. I then installed the Ultrathrust and got 15,900 with the same prop. I then dropped down to a 9x7 APC and got 16,400 rpm. My numbers are consistent with the Ultrathrust adds. It is not uncommon to have two identical engines that turn different rpm's.