George Braly said:

I would suggest you go out and fly the airplane in cruise, at 17.5 gph  and 30”

Then reset the engine to 17.5 gph and 32”.

Fly it each way for about 20 minutes at the same altitude.  Note the speeds carefully with each configuration with the airplane fully stable.

Then land and download the data and plot it up in EGView or some suitable software tool.

Then study the differences.

I can tell you with some confidence that the parameters that matter to engine durability will be improved with one of those settings - - verses the other.

 

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Unfortunately, i'm away from home for awhile and can't do the flight.  And, believe it or not, the G900X doesn't support downloading flight or engine data.  The GAMI lean tests were a real pain.

But...i'm going to guess the 32" setting is easier on the engine than the 30" setting (with FF at 17.5GPH and RPM at 2500 in both cases).  Because "leaner is better" and the temps should be cooler at 32".  And if the horsepower is truly the same, the airspeed should be the same in both cases.

If my guess is right, should i conclude that when LOP on the TSIO-550E in cruise, one should use FF to pick desired horsepower, and raise MP as much as practical?  But not so high that the engine "complains".  And not higher than TCM recommends for continuous use (which i think is 32").

On the other hand, if I'm wrong i really missed the boat after taking the advancedpilot engine management course.