Originally Posted by
peterh337
BTW, I don't believe LOP gives you more
MPG, compared to peak EGT, other than as a result of flying slower
I did some tests, at a constant IAS, RPM, etc and any difference was below the measurement resolution which was about 1%.
Correct. Ignoring changes in RPM setting, 75% power achieved LOP vs. peak both achieve very similar Specific Fuel Consumption, that is the same power per gallon of fuel and hence the same MPG. This is fortunately true both in theory and practice.
As a note, prop rpm seems to make a substantial difference to MPG when LOP (I.e. generating 75% power with a lower prop rpm is more efficient than a higher prop rpm)