I feel like I should know this "Search" didn't help much. Could someone please point some info out to me!

 

Detonation results when part of the unburned fuel mixture explodes violently. because the pressure rises so quickly that parts of the engine vibrate. hence, engine knock.

preignition results when an overheated surface in the combustion chamber ignites the fuel mixture. now, ping is a light tapping sound that can be heard during preignition.

preginition is similar to detonation, but the actions are reversed. detonation begins AFTER the start of normal combustion. preignition begins BEFORE the start of normal combustion.

i hope i didn't confuse you more

 

That's a very helpful overview. I have one question though; which is more destructive?

 

Very good explanations --- from my limited experience I would have to lean towards Detonation as being much more destructive....very hardcore detonation can blow a motor nicely....and has, many times.


[Modified by neo1z, 2:53 PM 2/23/2003]

 

I found out recently that the knocking noise is actually the cylinder walls vibrating, I use to think it would either be the rods or the pistons or something of that nature, go figures.

 

Another question; why do I hear that knocking sound coming from the engine after I turn off the car? Is it related to knock and preignition?

 

no thats cheap gas/ low octane the gas is not burning clean and is still trying to combust.

 

By not burning clean do you mean not burning all the way through?

 

Describe what you mean by a knocking sound AFTER YOU TURN OFF THE CAR. Knocking, preignition, detonation all are happening while the engine is running. After you turn off the engine its normal to hear some creaking & tapping noises which are just the parts of the engine moving as they cool off.

 

Ok thanks, that's what I wanted to know.