anyone know the design resonance of the engine mount/subframe for g2’s? as to what point it natually occurs…estimates of resonance frequency.? it seems to be about 2400 rpm on my stock b17a1. i am talking about the rpm where the largest displacements of engine to mount occur.
and to that end probably a point where you never really want your shit to be toolong… :sleep:
thats a good question
2ndary resonace
there is also a large displacement response at my steering column and roughly most of the cabin components at 800prm or so when she is ideling down low. after full warmup like at a stoplight for awhile. this is kind of to be expected i guess, but as our cars wear, this is where most noticeable audiorattles come into effect…just thinking. stop me if you can :blah:
How are your motor mounts? I had a lot of cabin vibration at warm idle before I replaced my front motor mount, that cured it.
I’m not sure if it is a resonance issue so much at lower RPM. Might just be that it is more noticeable because it is slow, the pulses cancel more at higher RPM.
I get a pretty good vibration at 1800-1900 rpm on my 92 B18A Ls auto. That’s light acceleration between 30-35 mph. Usually more when the car is cold.
every object has a resonant frequency (some multiple)…its the frequency at which the object begins to vibrate with such force that it cancels out certain other frequencies, this in most situations can cause extensive wear if allowed to occur for a period of time or actually be catastrophic. piston powered aircraft for example have their tachometer marked with a restricted operating range denoting the rpm at which resonant frequency is most likely to occur (commonly between 2000-2500 rpm). resonant frequency is essentially what causes valve float (amongst other things) but its because of the resonant frequency of the springs, not the engine as a whole. i have been searching around trying to see if their is some theoretical equation to determine this from the parameters of the engine…thus far i have not suceeded. but someone should have some further information on this topic, one would assume.