This event is a tractor-pull, in which you pull a sled that's progressively digging itself further into the dirt the farther you go. So these engines are made to have insanely high amounts of torque, meaning that when something fails, they've got more than enough power to just rip themselves to pieces.
Or if you prefer, that dang ol motor got so much twist it done twisted itself right on outta there.
Every time I see some redneck with their pickup truck modified to spew out black smoke like that, I find myself wishing this would happen to them.
Also, my brother is getting his masters in ethnomusicology at Bowling Green University right now.