Granted, yes technically it CAN happen in any motor... but if you are experiencing knock in a NA motor, you have something wrong with your motor. No NA should have knock if the motor is working properly.

The common reason for KR we experience with Supercharged/Turbo'd motors is pre-detonation knock which pulls timing and causes issues.
http://www.grandprixforums.net/what-...here-1507.html
Old thread but very solid information. Should explain it better.