2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Detonation?

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Old Jul 9, 2003 | 09:13 PM
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Detonation?

What does "Detonation" mean



edit -gah sorry i didnt mean to spam i should just added to first post

Last edited by DEZERTE; Jul 9, 2003 at 09:15 PM.
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Old Jul 9, 2003 | 11:45 PM
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nobody knows what happens when detonation occurs? me either but i know its bad
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Old Jul 9, 2003 | 11:51 PM
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Gas igniting before it should. PING bye bye apex seal
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Old Jul 9, 2003 | 11:51 PM
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Originally posted by DEZERTE
nobody knows what happens when detonation occurs? me either but i know its bad
your engine blows up when it happens...

its when the sparkplugs lights the gas / air. but the flame moves too fast or in the wrong direction.

higher oct. gas burns slower. therefor reduces the chance of detonatoin.


the other term is pre- ignition. commonly also called detonation. this is when the inside of the engine is so hot, that when the gas and air enter. it is lit by the engine before the spark plugs even fire.
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Old Jul 10, 2003 | 12:38 AM
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Well, it feels like there is a hydraulic chipping hammer tearing **** up under the hood. GRRRRRRRRRRRRRRRR and bang! No power and you're dead...

It occurs a lot when you are running lean like a MF.
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Old Jul 10, 2003 | 02:29 PM
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****, that sounds terrible.. thanx
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Old Jul 10, 2003 | 04:46 PM
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how can we keep it from happening, on a piston engine its just like o well no big deal on a rotary sounds like its death.
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Old Jul 10, 2003 | 05:43 PM
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Originally posted by Mephis
how can we keep it from happening, on a piston engine its just like o well no big deal on a rotary sounds like its death.

actually on a piston engine its not "Oh well" It can bend rods, destory cams, Damage bearings, and more. Yeah detonation is horrible for a rotary and should not be taken litely.

To prevent detonation keep in mind

Higher octane will reduce it
stay away from high boost levels
Check oil levels in your car. Oil reduces tempatures
Stay away from lean conditions
Clean your fuel filter and always check your fuel lines and pump.
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Old Jul 10, 2003 | 06:52 PM
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Originally posted by Scott 89t2
its when the sparkplugs lights the gas / air.
No, this is called ignition. The spark plug is supposed to ignite the air fuel. Detonation is when the air fuel mixture ignites from the heat and pressure of compression in the engine. The pressure from detonation is tremendous compaired to that of normal combustion from the ignition of the spark plug.
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Old Jul 10, 2003 | 06:54 PM
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Originally posted by Project84
No, this is called ignition. The spark plug is supposed to ignite the air fuel. Detonation is when the air fuel mixture ignites from the heat and pressure of compression in the engine. The pressure from detonation is tremendous compaired to that of normal combustion from the ignition of the spark plug.

ummmmm. He is right and wrong. If a sparkplug gets to hot, it will act as a glow plug and detonate the fuel/air before specified combustion.
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Old Jul 10, 2003 | 06:57 PM
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too early could cause the motor to try to rotate in the opposite direction. But the detonation from over pressuring a specific octane of fuel is damaging because the engine parts can't stand up to the pressure.
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Old Jul 10, 2003 | 08:14 PM
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well I was close enough... detonation is when the flames are going the wrong way as posted above. vrs pre-ign which is when it's too early caused by heat.

detonation is still most likly after the spark plugs light. otherwise the term pre ign. would be useless. it just means other parts of the fuel inside the engine are being lite at the same time.


"Detonation (also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.


PRE-IGNITION
Another condition that is sometimes confused with detonation is "preignition." This occurs when a point within the combustion chamber becomes so hot that it becomes a source of ignition and causes the fuel to ignite before the spark plug fires. This, in turn, may contribute to or cause a detonation problem.


Instead of the fuel igniting at the right instant to give the crankshaft a smooth kick in the right direction, the fuel ignites prematurely (early) causing a momentarily backlash as the piston tries to turn the crank in the wrong direction. This can be very damaging because of the stresses it creates. It can also localize heat to such an extent that it can partially melt or burn a hole through the top of a piston!"

http://www.misterfixit.com/deton.htm



Last edited by Scott 89t2; Jul 10, 2003 at 08:33 PM.
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