Detonation and glow ignition?

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Detonation and glow ignition?

Postby kw107 » 14 Jan 2006, 21:00

Whats the difference between those two? I know that glow ignition starts with a contact to a hot detail ; detonation needs a spark from a spark-plug when the air/fuel mixture is lean. Detonation also causes glow ignition. Are these phenomenons the same or not. Thanks!
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Postby Harry Flatters » 16 Jan 2006, 18:38

Kristjan, my understanding is this.

In normal combustion the fuel / air mixture is ignited by the spark plug and a flame front spreads progressively across the cylinder, creating an even rise and fall of the pressure in the cylinder and applying an even force to the piston.

Glow ignition is, as you say, a situation where the mixture - or part of it - is ignited by hot spots in the cylinder as well as or instead of the plug.

Detonation is where part of the unburnt mixture ignites when it shouldn't, causing additional flame fronts in the cylinder. There can be a number of reasons for this, one possibility being glow ignition. Detonation is often used to refer to unwanted burns after the plug has fired; a burn before the plug has fired is referred to as pre-ignition.
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Postby Miss Icey » 16 Jan 2006, 21:25

Det/Pink/Pre-ignition is normally a description of, well, pre-ignition, the fuel/air mix being burnt before the spark. You don't tend to get it much on NA engines unless its high compression or with very badly adjusted timing.
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Postby kw107 » 16 Jan 2006, 21:28

Thanks! I had a major discussion over this with a friend. He says that those two are the same, I say they're not.
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