Detonation is usually indicated by high CHT and rough running. Detonation is a result of fuel characterisics ( octane rating ) incorrect fuel/air ratios, high CHT,or excessively high manifold pressure in relation to RPM. Detonation becomes more pronounced and destructive as tempretures increase.
Round engines that are supercharged need special care as it is really easy to overboost and the inevitable result is either a cylinder departs or a piston fails, either way it is not good.
Turbo Charged flat engines are also prone to overboost if the waste gate or dump valve fail.