I've read through the recorded processes needed to flight-qualify the Wright and P&W twin row radials prior to WWII. Crank dyanmics are increadibly convoluted, and that was on short two-throw cranks. Our relatively limber and long cranks are no doubt spectacularly difficult.
Yes and just the same for the aircraft "Inlines" (Allison and Merlin V-12's) All kinds of harmonics mostly controlled by friction dampers and asessories driven by torsional shafts.
I'm rebuilding a F head Willys (Jeep) engine at the moment.This 4 cylinder engine with a redline of about 4000 rpm has no damper.
