Greeting all,
I'm hoping someone could help me out with a small headache I'm struggling with. I'm rebuilding one of my air files and tho I've got the max HP, engine drag (about 12% across the board), fuel consumption, prop speed and proper thrust I've discovered my fuel burn rates and HP go WAY below what they should be at cruise setting. My 'J' value is almost constant from 1800-2300, but tho my BHP is correct at full thrust at 2000 RPM I'm over 100HP under what my docs say my output should be. I don't have enough HP even if engine friction was 0. Since the 'J' value barely moves there's not much I can do with prop efficiency and there's not enough points in record 508 to compensate for the quickly falling HP.

Any ideas ?

Its a Curtiss D-12
carbureted
1:1 prop drive
470hp @ 2300 .58 lb per hr per hp << perfectly dialed in
415hp @ 2000 .54 lb per hr per hp << Should be 415/2000 but I'm getting 310hp BEFORE engine drag applies, about 105 pph burn rate
210hp @ 1850 <<< My eco cruise setting is 1850 rpm but 210 HP CANT be right, it should be about 385hp