the apparent magic of detonation

[molecule]

so your theory on life is merely
"DRUGS ARE BAD"

you sure you dont want to include any further information
like why the american government would bother to be the largest distributor and producer

oh and i'm the one who doesn't understand
yet you guys cannot provide substantial written evidence without getting pissed off
you just say...others have proven...i will blindly follow...
even though i have no f'ing clue...they told me how it is...
well how is it...?

i think you are a fool to believe that heat or even fuel 'solely' caused that damage
damn strait you are done here

[molecule]

prove me wrong...dont you want the truth...?
i know i do

[onegammyleg]

molecule

It has already been clearly explained the causes and effect of detonation are well known and are no mystery.
In fact I have seen much worse condition pistons than that example you showed.
Detonation is triggered by presure and heat , it causes an extremely fast uncontrolled combustion that is locallised putting extreme pressure on one spot rather than across the whole crown of the piston.
If you are thinking that it is magically amazing high presure to do this you are wrong.
Get a piston , eveen a good one , put it on the ground and chop it with a sharp axe and you will cut it in half.
Turn the axe head over and strike a piston with the blunt end and it will most likely not break.
Same forces but spread over more area.

Your insistance that detonation has some connection with unknown forces is way out of the ball park.
You may wish to believe such things and thats your right but its not backed by science in anyway , more likely just backed by your wishing it was true.

I am not contributing to this thread anything else.

[molecule]

how did they get the axe in the combustion chamber...???
i think you are on to something...
but YOU still dont know what it is...
i dont care how much pressure and heat you put in a chamber...it cannot form fuel into a sharp edge...
even if that piece missing from the crown broke off first and impaled the piston creating that hole
it would have taken the rings with it...
there is a different energy that causes detonation at this level

say it ... say it... say it

[kps]

Originally Posted by brick

And for the kids in the audience, say no to drugs!

I dunno. A few grams of haloperidol could do wonders.

[JanGeo]

The piston made from aluminum and the rings from tempered chromium steel totally different melting points. As soon there is a hot spot on the piston or a bad seal on a ring you get blowby which acts like a cutting torch forcing hot plasma gasses through the opening and burning away the metal. The same can happen in a valve or valve seat made from high temperature alloy metal - as soon as enough high pressure burning gasses pass over the valve leak it starts to burn away metal with each stroke. In normal combustion the flame stays in the center of the combustion chamber pushing evenly against all sides and against the downwardly moving piston.

[molecule]

alright....
so we have aluminum with a fairly low melting point of 1200°F
and that explains that...

but that doesn't explain what detonation is to me clear enough to be fully convinced that destructive energy spikes could be contained in fossil fuel...
high heat melting aluminum would then be fairly easily achieved in a combustion motor.
perhaps i dumped too much faith on that one piston...
you guys will never let me recover from that i'm sure...
before this thread im sure you would easily have believed anyone that uses terms like 'flamefront collisions' as a detonation truth...
well clearly its not a truth...
so lets see if any more misconceptions can be fully irradicated....

in fact...i dont see any evidence in this thread for any source of energy spikes
technically speaking
high heat in the engine to melt a piston is not an energy spike

[JanGeo]

The compression of an engine without ignition is from 120-200psi depending upon the compression ratio of the engine. The ignition of fuel produces a burn time of many degrees in fact my xB timing is advanced as much as 38 degrees BTDC under light loads and I am sure that it continues to burn as the piston is moving downwards or else they would not ignite it so soon because they would want the peak pressure to occure after TDC or else the engine would want to run backwards. That is an example of slow burning. Under heavy loads the timing is retarded to just a few degrees BTDC (Before Top Dead Center) and since the piston is confining the gasses to such a small volume it can burn more quickly (less distance for the flame to travel) with less of the heat energy being absorbed by the engine cylinder walls because less of the walls are exposed to the flame because the piston is covering it almost completely - actually a few degrees BTDC the piston is essentially all the way up in its travel. Now you have all the air and fuel charge compressed into a small space and then ignition occurs further increasing the pressure even more. But because it burns somewhat slowly (in terms of crank rotation) the piston is moving downwards reducting the pressure as it is rising from the thermal expansion and production of gasses from the complex hydrocarbon fuel breakdown from combustion. This produces a smooth increase in pressure and transfer of energy to the crank. If fuel ignited really quickly there would be no need for timing changes / advancing.

[molecule]

hastings confidently believes all detonation and pre-ignition is caused by colliding flamefronts
http://www.hastingsmfg.com/Service%2...reignition.htm

[gameshowbuzzer]bbbbbzzzzznnnnntttttt[/gameshowbuzzer]

the only other significant theories i'm seeing is spontaneous combustion of unburnt fuel/air
are you people seriously going to just put faith in spontaneous combustion and merely discredit such a notion as teslas...?
and even go further to say that teslas idea is crazy...?
wow...i mean...to me...its nearly the same thing...
but at least tesla has scientific support...where as spontaneous combustion has none...
fuel just MAGICALLY spontaneously combusts..???
and this is technical enough for you to lean back in your chair satisfactorally...???
well at least i got you to admit its magic...lol

ALLEN W. CLINE (AEE: Aeronautics Education Enterprises)
"Unburned 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."

[molecule]

here's the full text...and i find it fairly sufficient...
i think we can lay this thread to rest...
great article
http://users.adelphia.net/~digitalco...reignition.txt