Raptor 90 ??
I have about a gallon or two through my R60 with the OS91. Running the 12 tooth pinion and 93 maingear. I may try the 94 maingear in the future. Hover at 1650 and upstairs at 1800 rpm with 680 blades. The original 60 clutch was pretty much gone after a gallon, the 90 clutch seems to hold up much better. I added metal A arms and flybar hoops, a 24oz fueltank, Mr. Carbon frames on top of the metal frames (very rigid and still lighter than the TT heavy frame), extra bearing on pinned torque tube. Rick's O ring upgrade, metal fan (plastic one is junk) and a metal swashplate. I'm now experimenting with Curtis' Perry pump setup.
Fritz