Performance and Technical information on engines for
What is "detonation" and how does it affect the engine?
Detonation refers to a type of abnormal combustion that is usually preceded by
pre-ignition. It is most often caused by a hot spot formed in the combustion chamber. As
air and fuel is drawn into the combustion chamber during the intake stroke, this hot spot
will "pre-ignite" the air fuel mixture without any spark from the spark plugs.
Detonation exerts a great deal of downward force on the pistons as they are being
forced upward by the mechanical action of the connecting rods. When this occurs, the
resulting concussion, shock waves and heat can be severe...spark plug tips can be broken,
or melted, and other internal engine components such as the pistons or connecting rods
themselves can be damaged.
Left unresolved, engine damage is almost certain to occur, with the spark plug usually
suffering the first signs of damage.
Remember, when you observe signs of detonation or pre-ignition by examining the spark
plugs' firing tip, you are observing a symptom of another problem.
The trick is to figure out what caused the hot spot to form in the first place. You should
seek professional guidance to determine the root cause of the problem.
Please review the following reference chart to examine
the symptoms, causes, and results of knock and pre-ignition.