Detonation

Detonation is commonly found in cars that are highly tuned. When portions of the gas in the combustion chamber, generally the portion of gas at a corner, most far away from the spark plug self ignites, it is known as detonation. In the condition of detonation, the self ignition of that portion of the gas will be right after the firing of the spark plug, not along with it.

Besides fouling, Detonation is considered to be the worst enemy of spark plug. Detonation can break off ground electrodes or even break the insulators. Quite often, pre ignition is responsible for ignition. This is how pre ignition and detonation are related. Tip temperatures of spark plugs can peak to over 3000°F during a combustion process, especially in a racing engine. Another reason for detonation is the hot spots in the combustion chamber. These hot spots will cause the air/fuel mixture to pre ignite. Pre-ignited explosion inside the combustion chamber will try to force the piston downwards, where the piston is supposed to be forced upward by the mechanical action of the connecting rod. The result is that, the piston cannot go downwards due to the upward motion of the connecting rod and also the piston cannot go upwards due to the force of the premature explosion, and the piston will rattle from side to side. This resulting shock wave causes and audible pinging sound. This is how detonation is explained. The main damage of the engine due to detonation is from the excessive heat produced.  Detonation can also damage the spark plug by the elevated temperature as well as the accompanying shock wave.

More Car Driving Tips and theories

1. Pre-ignition
2. Spark Plugs: Heat Rating and heat Flow Path
3. Misfires
4. Types of Abnormal Combustion
5. Tip Temperature
6. Spark Plug Basics
7. Fouling
8. Maximizing Combustion
9. Spark Plugs
10. Shakocho