Points taken guys... no harsh critism meant.. but my point is that I see a lot of NEW gasser guys get hung up on RPMS when in reality they should be paying much more attention to how the engine actually sounds, runs and flies the airplane. With gas r/c engines RPM is far less important than it is with glow - as most of our gas planes are significantly overpowered a few more or less RPM really won't be noticed (that is if you build light airplanes) .. It is not always best to get the absolute last eon of power out of an engine either - some times you want to run it less than full bore - means stuff lasts longer. In the racing world we call this detuning. A racing marine engine might last 15 hours max... the detuned version will last 250 hours... big diff.

As far as power, thrust and RPM - In reality the only true way to determine the real power output of any engine is to measure its output on a dynomometer under a real world load. A prop spinning on the ground (i.e. static thrust) does not really do much to estimate the true thrust ratio or power output of an engine... it also is not the best thing for an engine.

So to recap - yes, I am no stranger to RPM... you can bet in the racing world I pay very close attention to it... however when it comes to my hobby engine, if its running the right temp, has a good idle, transition, and can put my plane out of sight.... do I really care if I am not getting every last RPM out of it .... probably not. I would also argue that the best tuning point for any r/c engine (with the exception of racing) is one that is a compromise of idle, transition and WOT performance... often tuning for max RPM shunts the performance of midrange and idle. 'Nuff said.


Nogyro - you might want to use an inline tach (i.e. inserted at the hall effect sensor connector). My guess is your reading is off. The DA50 on a 1/4 wave pipe and performance PORTING did not spin a 22x10 at 7200 RPM, somehow I don't think that $20 glowbee tach is quite telling the truth....


Just adding a little color to the commentary that 's all!
DP