[Wikipedia](https://en.wikipedia.org/wiki/Engine_knocking) isn’t clear, seeming to say they’re synonymous, then later implying they’re not.
What’s the difference, if any, between the two?
In: 3
Knocking is pre-ignition. Detonation is when the pre-ignition transfers from a burn to a detonation.
During regular operation the engine will ignite the fuel/air mixture in the cylinder. The fuel/air burns in a controlled manner that creates pressure pushing the piston down. For this to happen, first the engine uses the piston to compress the fuel/air mixture in the cylinder. When you compress a gas, it heats up. Heat it up too much and it will ignite and start burning before the spark plug fires. This means the fuel/air is burning and generating pressure while the piston is still moving up for compression. This can create severe pressure spikes in the cylinder and result in damage to the motor.
Detonation is when the conditions get severe enough that the burning turns into an actual explosion. When this happens the speed that the flame is spreading through the fuel/air mixture is faster than the speed of sound through that mixture. This is solidly in the category of “not good”.
The terms are often used interchangeably because there’s not much reason to distinguish between the two in practice. Both can (and will) cause damage to an engine and potentially destroy it. You can’t really tell the difference between the two from the outside while the engine is running. The end results and root causes are often the same. The nit-picky determination of which occurred in the cylinder is usually not needed.
Latest Answers