det...
29-10-2003, 03:54 PM
#1
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det...
Ok I know theres been loads and loads of threads on this in the past but I just wanted to know the answers to a couple of questions...
In high speed/high load situations... can you hear it?
Are there any symptoms, or is it all over too quickly?
Alex
In high speed/high load situations... can you hear it?
Are there any symptoms, or is it all over too quickly?
Alex
29-10-2003, 03:56 PM
#2
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from what i rememeber from various essays...
det is not the same as pinging
pinging is easily audiable
det is not
det must still be audiable but i presume its impossible to hear inside the car without detcans
i stand to be corrected tho...
det is not the same as pinging
pinging is easily audiable
det is not
det must still be audiable but i presume its impossible to hear inside the car without detcans
i stand to be corrected tho...
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29-10-2003, 04:05 PM
#8
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i think the term is pinging and people incorrectly pronounce it as pinking...
i mean... what's pink about it?
also which is the 1 with the 2 flame fronts meeting and which is the one where the burn hits the piston on its compression stroke?
i mean... what's pink about it?
also which is the 1 with the 2 flame fronts meeting and which is the one where the burn hits the piston on its compression stroke?
29-10-2003, 04:08 PM
#9
Oohhh... Now heres an essay post...
Wonder if i can find one of the ones ive already done?
porkie,
In the UK it is "Pinking" but much as i hate to admit it, our American friends actually got it right with "Pinging" as thats what it sounds like.. ping, ping..
We just missinterpreted it as usual.....
Wonder if i can find one of the ones ive already done?
porkie,
In the UK it is "Pinking" but much as i hate to admit it, our American friends actually got it right with "Pinging" as thats what it sounds like.. ping, ping..
We just missinterpreted it as usual.....
29-10-2003, 04:09 PM
#10
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Thread Starter
det is pinging in american terms... different terminology.
Jim what are you on about? two flame fronts?
Preignition is when the burn is started before the spark plug is fired... ie there is another source of ignition. Det is where the end gasses are heated by the combusiontion process to the point where they self-combust due to pressure and temp difference rather than being ignited by the advancing flame front.
Alex
Jim what are you on about? two flame fronts?
Preignition is when the burn is started before the spark plug is fired... ie there is another source of ignition. Det is where the end gasses are heated by the combusiontion process to the point where they self-combust due to pressure and temp difference rather than being ignited by the advancing flame front.
Alex
29-10-2003, 04:09 PM
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Well......
the burn ALWAYS starts on the compression stroke if you are timed BTDC...that is the whole point.
Detonation is ignition OTHER than when you want it. This can be due to local hot spots, low octane fuel, etc....
I've always called it pinGing but then again, I don't speak the queen's English either
the burn ALWAYS starts on the compression stroke if you are timed BTDC...that is the whole point.
Detonation is ignition OTHER than when you want it. This can be due to local hot spots, low octane fuel, etc....
I've always called it pinGing but then again, I don't speak the queen's English either
29-10-2003, 04:18 PM
#14
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Detonation occurs in the combustion process when the advancing flame front, which is pressurizing and heating the unburned mixture ahead of it, does so at such a rate that unburned fuel in that zone achieves its auto-ignition temperature before the arrival of the actual flame front. The result is that the unburned mixture combusts "spontaneously" and over the entire zone where the auto-ignition temperature has been achieved. The apparent flame speed in this zone is many orders of magnitude faster than that in conventional combustion initiated by a normal flame front, with the result that the local rise of pressure and temperature is significantly sharp. This produces the characteristic "knocking" or "pinking" sound, and the local mechanical devastation that this can produce on piston crown or cylinder head can be considerable. Actually, "knocking" is the correct terminology for what is a really a detonation behavior over a small portion of the combustion charge. A true detonation process would be one occurring over the entire compressed charge. However, because detonation in this strictly defined sense does not take place in the spark-ignition engine, the words "knocking" and "detonation" are used interchangeably in the literature, without loss of meaning, to describe the effects just discussed.
29-10-2003, 05:16 PM
#17
Hi,
This one will require an essay, and if its still required later il do one.
Detonation and pre ignition are two seperate entities IMO.
Pre ignition can be heard in "most" cases.
Detonation is very much harder to detect by ear and requires a listening device to localise it.
This one will require an essay, and if its still required later il do one.
Detonation and pre ignition are two seperate entities IMO.
Pre ignition can be heard in "most" cases.
Detonation is very much harder to detect by ear and requires a listening device to localise it.
29-10-2003, 05:18 PM
#18
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When my first Escort Cossie let rip at about 150mph (on speedo), I never heard anything. The first thing I knew was a slight miss, then another one and then oil over the windscreen and a plume of smoke across the whole mway!!! 
It all depends on what kind of speed you are doing as regards to when the DET happens, to whether or not you can hear it. (just read stu's post, so I have my Det and Pre-ign confused! )
Everytime I get anything like a missfire at high revs, my arse always goes in to overdrive!
It all depends on what kind of speed you are doing as regards to when the DET happens, to whether or not you can hear it. (just read stu's post, so I have my Det and Pre-ign confused!
)Everytime I get anything like a missfire at high revs, my arse always goes in to overdrive!
29-10-2003, 05:21 PM
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Originally Posted by Stu @ M Developments
Detonation is very much harder to detect by ear and requires a listening device to localise it.
12-12-2003, 07:21 PM
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Pink/ping ing you can hear. DET you cannot, not even with DET Cans.
Detonation = shock waves which can be picked up with the correct equipment. Don't understand what you are getting at Steve
12-12-2003, 07:55 PM
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I meant 'engineered to avoid detonation'
Detonation can be caused by either excessive temperature or excessive pressure of the fuel-air charge. Take that for granted - but how can you engineer a motor not to det' if you can't actually detect when you have reached the point of detonation? I mean you can obvioulsy ensure that cylinder head temp's etc are kept within tolerance, but if you cannot detect it, you don't know what the tolerances are....
Detonation can be caused by either excessive temperature or excessive pressure of the fuel-air charge. Take that for granted - but how can you engineer a motor not to det' if you can't actually detect when you have reached the point of detonation? I mean you can obvioulsy ensure that cylinder head temp's etc are kept within tolerance, but if you cannot detect it, you don't know what the tolerances are....