detonation and preignition?
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From: the not so stock tribe
detonation and preignition? i know that to take care of detonation you pull timing or use higher octane gas. but how about preignition?? is it the same as detonation ? can you cureit with less timing or better fule ?? or is there something different??
Re: detonation and preignition? i know that you can cure it with better fuel as higher octane fuel has a higher ignintion point, not a 100% sure on the timing so ill let some one else answer that.
Re: detonation and preignition? Pre-ignition is different. Detonation is the combustion smacking into the piston at the wrong time. Pre-ignition is your car running like a diesel (which is why it is sometimes call 'dieseling')
If you have an engine that is 'dieseling' you won't be able to fix it with timing.
Common causes of pre-ignition are hot spots in the combustion chamber.
Different design plugs, lower compressions, cleaner combustion chambers, and better gas are all ways to help with pre-ignition.
A good example of this is a nitrous car with too big of a shot and the wrong plug. You may pull timing, but as long as your plug electrode is providing enough heat to ignite the mixture as soon as it gets into the cylinder chamber, pulling timing wont do anything.
If you have an engine that is 'dieseling' you won't be able to fix it with timing.
Common causes of pre-ignition are hot spots in the combustion chamber.
Different design plugs, lower compressions, cleaner combustion chambers, and better gas are all ways to help with pre-ignition.
A good example of this is a nitrous car with too big of a shot and the wrong plug. You may pull timing, but as long as your plug electrode is providing enough heat to ignite the mixture as soon as it gets into the cylinder chamber, pulling timing wont do anything.
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From: the not so stock tribe
Re: detonation and preignition? how about less boost?
or to be more precise , put better headers to lower the restriction , thus lowering boost. will that help with preignition?
another question , are the tr6 plugs as cold as the NGK BR7ef plugs?
or to be more precise , put better headers to lower the restriction , thus lowering boost. will that help with preignition?
another question , are the tr6 plugs as cold as the NGK BR7ef plugs?
Re: detonation and preignition? agreed, since preignition occurs without spark, then retarding the timing would do jack.
you need to drop your compression, go to a colder plug, or run more octane..(or run some top end cleaner through the engine)
you need to drop your compression, go to a colder plug, or run more octane..(or run some top end cleaner through the engine)
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From: Nottingham, Notts, England, UK
Re: detonation and preignition? The above are correct. You could also skim the deck, tighten the squish and speed up the burn thus making combustion more efficient. Maybe you have got something wrong in which case something simpler would help,IMHO.
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Re: detonation and preignition? Skimming your deck 5 thou isn't going to noticeably increase compression. It may help with squish, depending on how the geometery of your piston to head is now.
If you are going to be pulling the heads off though, I would just recommend getting some port work done to your combustion chambers rather than decking them.
I wouldn't increase the header gasket thickness. I think this is one of the poorer ways to decrease compression because of the above mentioned reason.
Another suggestion would be to run a recessed sparkplug. A shorter plug, which runs with a recessed electrode will kill two birds with one stone: It will get the plug out of the heat, and decrease your combustion chamber size slightly.
Good Luck,
Kevin
If you are going to be pulling the heads off though, I would just recommend getting some port work done to your combustion chambers rather than decking them.
I wouldn't increase the header gasket thickness. I think this is one of the poorer ways to decrease compression because of the above mentioned reason.
Another suggestion would be to run a recessed sparkplug. A shorter plug, which runs with a recessed electrode will kill two birds with one stone: It will get the plug out of the heat, and decrease your combustion chamber size slightly.
Good Luck,
Kevin
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Re: detonation and preignition? The only true way to tell the difference between detonation and pre-ignition is to get a clear picture of the crank signal and ignition signal.
Pre-ignition creates a knock (blip on the KR sensor voltage) at a point prior to igntion.
Detonation creates a knock at a point after ignition.
Perhaps there is a scantool out there that can do it, but I don't know of one. Tech2?
Other than that, I really can't think of a rock-solid test to give a 100% difference between the two.
Good Luck,
Kevin
Pre-ignition creates a knock (blip on the KR sensor voltage) at a point prior to igntion.
Detonation creates a knock at a point after ignition.
Perhaps there is a scantool out there that can do it, but I don't know of one. Tech2?
Other than that, I really can't think of a rock-solid test to give a 100% difference between the two.
Good Luck,
Kevin