When at full throttle with 4 blades and maintaining 5.5k rpm, your idle will be non-existant. The motor will NOT idle! This has been a problem since the beginning of time. We know that with the increase of blades at the hi rpm's put out by the engines, efficiency greatly decreases. For a 4 blade prop to be effecient, the rpm's need to be below 5.5k as you are aware. Needless to say nothing single cylindered except the RCV's will run like this. Even the RCV's are less effecient with 4 blades but the result is closer to scale and what you are after. Good luck in your testing!