I have a question for those who know about crankshaft vibrations, is it determined by mechanical factors or dynamic influences like ignition type and ignition timing? So the setup I have came out of a Mooney, IO 360 A1A with C/S Hartzell that had the 2000 - 2250 no continuous RPM restriction. This will now be ran with a full EFII system and the timing will be 30-25 BTDC (depending on map) so does this change the restriction or no? Thanks
+1 what Scott said. You now have an untested, experimental combination, and the usual victim is the propeller. You should not assume anything based on vibration perceived in the cockpit.
You can make some logical assumptions, although you might not like the logical result. Vibration frequency (or frequencies, plural) is based on mass and connecting stiffness. Here the masses and connecting stiffnesses are not being changed, so in general, all natural frequencies will remain the same.
Resonance happens when a natural frequency is matched by an exciting frequency...a driving force. The primary driver is combustion events, and here you're not changing the frequency at which they take place. What you
may be changing is the amplitude...the power with which they twist and bend the components. The increased amplitude is magnified by resonant behavior; in resonance, material stress can get very large in a hurry.
The logical result is that the current prohibited RPM range should be observed with real diligence, and you might even want to widen it a bit.
I say "may be changing" because we really don't know the degree to which your new fuel and ignition systems will actually increase the force of each power stroke. If we believed some of the claims, your new prohibited range should extend from 1800 to 2800
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Ok, I'm kidding....sorta.
It sounds like you're using a pre-loved propeller from the Mooney, so you should also be aware that some part of each aluminum blade's finite fatigue life has been used up. It's another good reason to avoid the prohibited range.