When you said the rings where the only thing hurt by the detonation that doesn't seem to be possible, to me All of the motors hurt be detonation I have seen heat the pistons up collapsing the ring lands and sometimes breaking the ring lands out of the cast pistons and sometimes even the forged pistons, which ends up transferring piston and ring material into the cylinder walls. I have also seen damage done to the aluminum cylinder heads and valve seats from detonation, maybe your engine builder needs to take a real close look at the entire motor very carefully Or maybe the rings where hurt some other way than detonation Like to tight of a end gap