looking at some info from about 1990 out of a Byron kit it shows then rpm max speeds of 16k to 19k for the then present setups. these numbers are for the early 61 to 65 size engines. That was of course for a Byron fan unit. So would a present day heli engine made to turn a max 18k work in their place? Is a heli engine ported different than a plane engine of the same size for different power bands?? For instance MDS sells several engines in the same size for both. Only apperent difference is the bigger head. Isn't 18k a respectable rpm for a guy who doesn't care to rip the sky apart. Just wants to have an easy going jet?