Quote:
Originally Posted by aerohead
hummingbird,knock is synonymous with detonation,a condition which occurs in the cylinder of the engine associated with piston slap caused by uncontrolled combustion which can lead to rapid engine damage.------------Lugging is described as a condition which exists when operating a vehicle in a gear too "high" for the rpm of the engine,which causes the vehicle to "buck" and shudder,immediately before the engine stalls.Lugging causes "jerk",which is an instantaneous acceleration in the power-train,and if maintained,can lead to bearing failure or gear failure under these instantaneous loads.
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I would argue with that. Its not really uncontrolled any more than normal. It is suspected that it happens if/when the flame front strikes a pocket of stoich mix while the surrounding area is lean. the stoich burns faster and causes an uneven pressure spike on the bottom of the cylinder(against the piston) which ignites that fuel and creates very small pockets that detonate under the intense pressure and heat.
All said and done the combustion event is no less controlled(as there are no means for controlling the flame front).