September 29th, 2016, 11:59
The problem is quite simple; the only way to control RPM, at least that I know of in CFS1, is through throttle. As, in "real life", that throttle control ceased at 6,300RPM (it was a typo on my previous comment), and would automatically raise, and stay, at 9,500RPM. how could we mimic that with the needle deflection?
Add also the "burst" action that you wanted to use. It would certainly show on the RPM, and it should not.
It would have been the same problem with a constant speed propeller but, at least, CFS1 AIR files could deal with that. I doubt that the FS98-style jet AIR file can.