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The reduced engine speeds allow more time for autoignition chemistry to complete thus promoting the possibility of pre-ignition and so called "mega-knock". Under these circumstances, there is still significant debate as to the sources of the pre-ignition event. [3] Pre-ignition and engine knock both sharply increase combustion chamber temperatures.
It's commonly known as "Detonation or Knock". Engine management systems can overcome pre ignition by the means of a knock or detonation sensor. The sensor will detect pre ignition and retard the engines timing to protect the engine from damage. Undesired engine behavior will occur such as loss of performance or power.
In spark-ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
The detonation velocity values presented here are typically for the highest practical density which maximizes achievable detonation velocity. [ 1 ] The velocity of detonation is an important indicator for overall energy and power of detonation, and in particular for the brisance or shattering effect of an explosive which is due to the ...
In spark ignition internal combustion engines, knocking (also knock, detonation, spark knock, pinging, or pinking) occurs when combustion of some of the air/fuel mixture in the cylinder does not result from propagation of the flame front ignited by the spark plug, but when one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.
Higher compression ratios can make gasoline (petrol) engines subject to engine knocking (also known as "detonation", "pre-ignition", or "pinging") if lower octane-rated fuel is used. [5] This can reduce efficiency or damage the engine if knock sensors are not present to modify the ignition timing.
Whereas age-degraded gasoline may simply polymerize, evaporate, and thus lose its flammability, age-degraded gasoline-ethanol blends can cause severe damage if allowed to sit in an engine. Automotive engines addressed this with the mandated shift over to ethanol-tolerant metals and seals, and with the use of smart electronic fuel injection ...
Due to the high temperatures at this mixture, the detonation of the fuel-air mix while approaching or shortly after maximum cylinder pressure is possible under high load (referred to as knocking or pinging), specifically a "pre-detonation" event in the context of a spark-ignition engine model. Such detonation can cause serious engine damage as ...