The rattle dampers come from the industrial diesel world. People have tried them in performance applications and they are notorious for breaking crank snouts.
9.9/10, what you see are tuned elastomer type mass dampers (ATI, BHJ, etc).
BHJ has a decent white paper on it:
https://harmonicdampers.com/index.php?m ... &chapter=0
Other than crankshafts, the valvetrains are super susceptible to harmonics. The type of drive helps a lot (belt transmitting the least), but they take up more space than a gear drive. Engine designers, going back to Cosworth with the DFV have used quill drives and other dampers in the gears to help with this.
Builders who used carburetors often knew all about this as fuel could / would froth in the float bowls if any of this wasn’t controlled. You can feel it in your hands / feet on an old motorcycle without a balance shaft too as the engine passes through these zones. Some engines were notorious for flywheel bolts backing out if they spent any amount of time at these rpm’s, you just have to pray your scattershield holds when that happens!
