My race motor was balanced,, the thing hardly moved in the engine bay.
A k-motor won't let go. I tried destroying one a number of years ago. Involved were a 4K, a brick, and a couple of mates armed with six packs. Brick installed on throttle, valves bouncing, beers consumed. Approx two stubbies later, engine screaming, boys disappointed with lack of action. Jif introduced into engine oil. One stubbie later, toxic fumes and steam eminating from every orifice in engine. Still powering along, although at reduced revs. Finally ran out of fuel and seized solid.
They don't tend to let go.