Originally Posted by Intruder
Rumors of engine damage due to "oversquare" MAP/RPM combinations apply ONLY to supercharged engines, and are not generally applicable to light piston engines.
I'll go you one better:
Rumors of engine damage due to "oversquare" MAP/RPM combinations are horesecrap even for supercharged engines.
On the R2800's (2 speed centrifugal supercharger) on the DC-6's I used to fly, Take off power was 59.5" MAP and 2800 rpm, Climb, I think was 43" and 2400 and high power cruise was 32-34" and 2200 RPM. The only time we weren't "oversquare" was on descent.
For what it's worth, the direction the manual gives for the O-470R in my Cassna 180 is for a desired power setting, use the minimum RPM that gives smooth operation (or words to that effect) And the MAP/RPM charts therein list plenty of combinations which are "oversquare" .
Seems that Teledyne Continental Motors and Cessna never got the "oversquare" memo.