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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.
Low-speed pre-ignition (LSPI), also known as stochastic pre-ignition (SPI), [1] is a pre-ignition event that occurs in gasoline vehicle engines when there is a premature ignition of the main fuel charge. [2] LSPI is most common in certain turbocharged direct-injection vehicles operating in low-speed and high-load driving conditions. [3]
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.
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.
Homogeneous mixing of fuel and air leads to cleaner combustion and lower emissions. Because peak temperatures are significantly lower than in typical SI engines, NO x levels are almost negligible. Additionally, the technique does not produce soot. [3] HCCI engines can operate on gasoline, diesel fuel, and most alternative fuels. [4]
Since diesel fuel is thicker than gasoline, it evaporates slower and therefore, they are not at all interchangeable. "But if you catch it in time, it could just be flushing out all the lines and a ...
In Europe, diesel cetane numbers were set at a minimum of 38 in 1994 and 40 in 2000. The standard for diesel sold in European Union, Iceland, Norway and Switzerland is defined by standard EN 590. Since 1 January 2001 EN 590 demands a minimum cetane index of 46 and a minimum cetane number of 51. Premium diesel fuel can have a cetane number as ...
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