u sure dude?? motorsaver airfilter are some of the best around. the only reasons it could have failed like that is human error.
Not securing the elbow tightly with zip ties
Not using air filter oil
Airleak
old air filter
Re using an air filter that hasnt been cleaned well.

Sry about ur engine. I suggest opening it up and inspecting the internals. Check for scratches and bits of dirt. Then buy the necesary replacement parts for the damaged areas. If its far to damaged buy a new engine. If its not damaged at all ur lucky. Also how do u know that the scratching noise from the bearings is dirt??could be loose piece check around the clutch and everything too and clean the whole car.