IO 550G & N are exactly the same engine. The prop governor limits the G to 2500 but with a STC you can bump it back to 2700.
Alexis wrote:
Depends on the engine version. Max. continous power for IO-550N is 2700 rpm, for IO-550G it’s only 2500. The “N” version is very happy at 2700, also that’s only 8 percent more revolutions per minute.Whatever “happiness” means in this case, I doubt it’s the same as “best efficiency”.
Engines typically achieve highest fuel efficiency somewhere near their peak torque rpm, which is a pretty flat rpm range for aircraft engines, but below the rpm that may require rich mixture for reliable operation. Regardless of when the engine was designed, this is a key design issue and was the product of forethought.
My O-320 and CS prop are smoother when running slower, so fully leaned out at say 2200 rpm makes for a nice experience, with maybe 23 inches MP and economical fuel flow.
