Admittedly I have skipped the second page, but would a “1-way bearing” utilizing sprags be more along the lines of what you are thinking Articzap? (Think 1 way, spring-loaded slip roller, no moving parts) I am positive I know exactly what you are talking about. I think you idea could be more constructively defined as a “lag eliminator”. While I cant see any type of gear driven Turbocharger style compressor brought to high enough speeds to make sizeable power mechanically, I can see it taking off quite a bit of the time needed to spool.
I am well aware of the rotational speeds that a Turbocharger can see, but I cant see how a setup such as the above would influence this negatively other than excessive complexity. There would be no increase to the shaft rotational weight, and bearings such as these are already widely used in applications that can easily see 40,000+ RPM. Not quite Turbine shaft speeds, however not so far out of the question that it couldnt be done.
Discuss?