Originally Posted by
A Squared
Don't know, only Eddie Dean knows for sure.
Regardless, your entire tangent about whether an engine is at sea level, is just that; a tangent and not a particularly relevant one.
LB asked you which would make more power; an IO-520 with all the knobs forward and the timing advance set to 20 degrees BTDC or the same engine under the same conditions with the advance set to 22 BTDC.
There was a point to the question, but instead of answering the question you started this completely irrelevant tangent about his use of "sea level" (Apparently you didn't know that "Sea level" is the standard reference for engine power output. )
The most charitable assumption would be that he is.
Sorry have not read all posts and not seen such a question.
22 BTDC would as more time to burn more fuel, the more fuel burnt in a sealed chamber has more energy, thus more HP.
Since the piston in a cylinder moves a greater distance in the first 90 degrees of rotation of the crank shaft than the second 90 degrees, it is desirable to have as much fuel as possible burnt in the cylinder at 0.000001 degrees after TDC.
Sea-level you refer is not just the pressure @ 16,000 feet temp will play a large factor -
https://en.wikipedia.org/wiki/Standard_sea_level
Using a "pressure" only and insisting it is Sea Level is - well wrong!