the idea that rotor profile power is represented by the manifold pressure or torque measurement while at flight idle on the ground is a good one, except for this: a rotor blade does not have a consistent angle of incidence/attack at any collective setting due to blade twist, therefore some portions of the blade will not be at 0 degrees AoA, and would be subject to small induced power requirements as well (at least I think).
[This message has been edited by lmlanphere (edited 21 March 2001).]