My apoligies then. I missed the point somewhere.

The only thing you actually get to experience is static performance. So in a way, with a fixed geometry prop, it has to be a point of reference.

In many cases with speed applications, the engine is propped up to the point where it can barely turn the prop on the ground.... and initial acceleration is terrible. But as the aircraft and engine accelerate, the prop gets into a rhelm where the prop works its best. On the ground, you simply never see the prop or engine perform.

Static has some corrilation to inflight performance. But its hard to quantify.

With the advent of some of the in-flight telemetry stuff, its becoming a bit easier to see real time performance.