Yeah, we can laugh now. But believe me, I wasn't laughing then! At the time, all I could picture was my engine melting down China Syndrome style, with me helplessly watching it happen.

 

did u guys read the link that slvr posted from the designer of northstar? yes, detonation IS a separate event. however, there is NO chemical definition for "explosion". any exothermic reaction can be an "explosion", we usually just talk about the relative energetics and whether or not its a good idea to practice a little extra safetly with a reaction. so for them to describe detonation as a radical reaction AFTER the spark like they did..... thats just wrong.

actually, 69 just gave the most accurate description I know of (although i still think hes trying to explain it to me... [&:]lol. dude, i know what knock is! just because i havent heard a gen1 sbc knock doesnt mean i dont know where it comes from). ive heard alot about carbon deposits making hot spots. The only issue i am coming up with is: I cant think of any reason why advancing the timing would cause extra heat. gasonline is the only appreciably source of heat. the timing of the spark doesnt affect how hot it burns, or at least i cant justify that to myself logically.... like i said in my previous post all I can think of is a perpetual knock due to purposefully igniting the mixture too soon. therefore some of the energy of the burn would oppose the rotation of the crank, until it passed TDC with the help of the other pistons, and then the remaining energy would go with the flow

 

I read it before it is included in the link I posted it Vizards site(I sort of repeated the two flame front portion in a response). I actually think the guy with the (flawed) chemical description and the artical are saying the same thing. The spark initiates the flame the flame progresses at some rate(influenced by densityof the fuel mix and the turbulant mixing of the combustion chamber pressure and heat) at some point an end gas is produced (hydrogen and oxygen maybe) the end gas blows up due to heat and pressure. The practical evidence is the tuning of the knock indicator if it was detecting a burn it would go off every time a cylinder fires. If it is a timing event that fires before the cylinder reaches its correct point to fire high octane fuel would not solve the problem as it does in most cases.Quote from artical.

DetonationUnburned end gas, under increasing pressure and heat (from the normal progressive burning process and hot combustion chamber metals) spontaneously combusts, ignited solely by the intense heat and pressure. The remaining fuel in the end gas simply lacks sufficient octane rating to withstand this combination of heat and pressure. Detonation causes a very high, very sharp pressure spike in the combustion chamber but it is of a very short duration. If you look at a pressure trace of the combustion chamber process, you would see the normal burn as a normal pressure rise, then all of a sudden you would see a very sharp spike when the detonation occurred. That spike always occurs after the spark plug fires. The sharp spike in pressure creates a force in the combustion chamber. It causes the structure of the engine to ring, or resonate, much as if it were hit by a hammer. Resonance, which is characteristic of combustion detonation, occurs at about 6400 Hertz. So the pinging you hear is actually the structure of the engine reacting to the pressure spikes. This noise of detonation is commonly called spark knock. This noise changes only slightly between iron and aluminum. This noise or vibration is what a knock sensor picks up. The knock sensors are tuned to 6400 hertz and they will pick up that spark knock. Incidentally, the knocking or pinging sound is not the result of "two flame fronts meeting" as is often stated.

 

typical "endgas", at least the way i THINK they are using the term, would be carbon dioxide (in a perfect world, but usually nitrogenous compounds and carbon monoxide, which is turned to CO2 in the cat). the unburned end-gas is just fuel which auto-ignites on a hot spot in the cylinder.
from what I can tell now, were just discussing semantics..... were not really disagreeing on anything anymore are we? the only thing i was disputing to begin with was the advice to stay away from 91 or 93 octane due to incomplete burn.

 

Wow my thread got hi-jacked![sm=hia.gif] lol

 

did ur problem ever go away? lol

 

Yes that problem did but now I have several others..Typical Camaro

 

love/hate right?
we know [8D][&o]