O540-J1A5D Power Setting Table

[Kirk]

Working from the tables in the Lycoming Operators Manual, I came up with this easier to use power setting table. I included settings for 2300 RPM(climb) 2200 RPM & 2000 RPM @ 75%, 65% and 55%.

Note that 65% at 3000' is shaded since it exceeds the 23" MP at 2000 RPM and below. That is the setting per Lycoming, but is not available for this prop/engine combo.

The limitations in the notes section are from my copy of the AFM for the M5-235C. The best service life notes are from an article I read quite a while back, can't remember the source.

[Rezrider]

It would be nice to develop 23"MP at 9000 ft but it's not going to happen, not in my engine at least. Maybe a brand new one would.

[Kirk]

Pretty normal, just because the chart gives you a value doesn't mean we can achieve it. I pull about 22 to 22 1/2 at 9000'

Kirk

[DeltaRomeo]

I suspect this thought will set the woods on fire...

Somewhere around 8000' MSL is where most normally aspirated engines can only produce 75% of its power due to the thinner air at altitude which means full throttle IS 75% power. As you climb higher it continues to decrease until you reach the effective ceiling. Any manifold pressure setting at this altitude less than full throttle is simply a lower power setting.

[Kirk]

D R, that sounds about right. Seems like there is some confusion about that chart and the performance tables it comes from.

Those are the values that would represent that particular %HP at a given altitude. it does NOT imply that you will be able to produce all the settings all the way up.

As you climb up and see that your aircraft drops below the MP value for let's say 75%, you now know that you are cruising at less than 75% power.

Maule didn't publish performance tables for the M5, so we don't have data on just how high that particular engine, induction system and prop combination will produce a given power.

Don't know if that explains it or just muddies it further.

Kirk