No knock, knock

[Bruce Plecan]

Does it seem reasonable that someone might come up with a
combination of timing, and fuel that goes into detonation, that
the knock sensor misses?.
  This happens to be a late model SBC.  
This happens with a few more degrees then with a identical
chip that triggers the knock with less timing?????.
  Any ideas?.
Bruce        Judge tru the case out about jelly saying jam is about
                   the samething.