[bongodriver]

apart from temperatures and increasing engine wear

which logic dictates are lesser in terms of level flight.........it has occurred to me that those limitations seem more geared toward RPM as opposed to boost, if 9lbs boost can be used for 30 mins then tchnically it is not limiting, usually a 5 min limit is the true factor, this is still a factorisation that applies today even in jets, TO thrust is a 5 min limit, anything below that is a MCT (max continuous thrust), I susspect the 30 min limit is really a limit in terms of oil cooling for the prop govenor system.