- Joined
- Sep 21, 2018
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- 2,762
KR is a result of detonation. To have ‘real’ (more on ‘real’ vs ‘false’ KR later) KR, you MUST have detonation. Detonation is the uncontrolled combustion of the intake charge. “Uncontrolled” means that the mixture ignites via a means other than the spark from the spark plug. In most cases, the uncontrolled ignition is due to a ‘hot spot’ in the cylinder. Hot spots can be caused by uneven combustion, spark plugs that are rated too ‘hot’, lean fuel conditions, breathing restrictions (exhaust / intake), bad gas, and so on. One problem in particular is the head gaskets. During an engine teardown, the head gaskets are NOT made perfectly round. Some of the gasket material actually protrudes slightly into the combustion chamber. Since the head gasket bore linings are made of metal the bit that protrudes into the cylinder will glow red hot, thus creating the potential for a nasty ‘hot spot’. This is an example of an area that should be checked and perhaps replaced with an aftermarket head gasket. In other cases, the ‘hot spot’ is due to unreasonably high cylinder compression. Either way, the ‘pinging’ or ‘rattling’ sound you hear is the result of the actual collision of the flame front produced by the ‘hot spot’ and the normal flame front produced by the spark plug. Typically, these two flame fronts are opposing fronts, meaning that they are expanding, or propagating toward each other, causing the collision. Real KR does NOT occur without detonation occurring FIRST.