RE: RPM range for Jett .35?
You should still be over or right at 18,000 with a 9x6
your 18,000 with the 8x6 isnt very strong at all. i bet some 25 size engines could do that.
make sure your tac is set on two blade prop.
if it can not reach 18,000 with a APC 9x6 and the correct fuel then you should call Dubb Jett.