RE: Evolution 58GX - what RPM's should it turn?
seen this before -
two things going on - one the case gasket /flange is narrow and the bolts can slightly loosen.
result is a gasket blows out -just like a muffler flange gasket often may do.
I just ran a write up/ test on the new 116 -uses much the same setup -but no problems and what a beautiful smooth runner !
it will now do duty in a Tug plane for gliders --
Like harnessing a race hose to rag pickers wagon--- (sniff)