Talk:Engine knocking

I deleted this para: "Knock is detonation within the cylinder. Uncontrolled combustion. It is not the same as pinging/pinking which is pre-ignition.". As far as I'm aware (25 years of experience with engines aware, that is), this is wrong - preignition and pinking ARE the same thing. It's also pinKing, not pinGing, though perhaps in some parts of the world it's called that? - I suppose the sound is a sort of ping GRAHAMUK 06:35, 3 Aug 2003 (UTC)

I clarified the difference between knocking and pre-ignition, and added some external links. In the USA at least, engine knocking is also called "pinging" (or just "knock"), but I've never heard it called "pinking". -- Arteitle 05:03, 17 Sep 2003 (UTC)

It's "pinking" in the UK. As my car used to suffer from it I'd describe the sound as a sort of tinkling sound.

Exile 16:08, 20 Jan 2005 (UTC)

what it is

Pre-ignition is the normal meaning of this, isn't it? Note that true detonation is a supersonic process. Many times people say that something detonates, but it doesn't really. Note that "supersonic" would refer to the compressed fuel-air mixture, so you can't call the result supersonic just for exceeding the speed of sound in sea-level air. AlbertCahalan 06:23, 7 Jun 2005 (UTC)

Pre-ignition is the igniting of the fuel by a source other than the actual spark. It does not follow necessarily that detonation will occur because of it. Detonation refers to the creation of a high pressure wave that traverses the combustion chamber potentially causing damage. This pressure wave is akin to the wave of a sonic boom.--=Motorhead 04:42, 12 Jun 2005 (UTC)

It's not really detonation unless that pressure wave travels faster than the speed of sound in that compressed fuel-air mixture. Given the high compression and the density of fuel, I would expect the speed of sound to be relatively high. I'd really like to see some proof that detonation occurs, because it's a fairly wild claim and because people so often casually call things "detonation". AlbertCahalan 02:20, 14 Jun 2005 (UTC)

The term detonation, as applied to internal combustion engines, is not new. (Not something made up by a couple of mechanics over a case of beer hehe!) Since the first works of Sir Harry Ricardo (Knighted for his work in this very area) in 1922 to the present there have been numerous research papers written on it. Probably the most studied area of engine performance since detonation limits maximum performance. The term “detonation is used to describe the very high pressure shock waves traveling at supersonic (compared to immediately local conditions) velocities (which is the only way you can create a shock wave). These waves cause real life broken parts and are observable on pressure traces taken from real engines. Your own ears will tell you something nasty is going on in the engine. For further proof read:

“The internal combustion engine in theory and practice” Vol 2 ch.2 “Detonation”[1] (http://www.amazon.com/gp/reader/0262700271/ref=sib_dp_pt/102-7987980-5543325#reader-page) by C.F. Taylor (The M.I.T. press) for an authoritative, detailed report from a founding researcher on the topic.

There are numerous other sources if you are interested.

Asside from the symantics of it all, the term "Detonation" is the defacto standard term used to decribe this phenomenon in the field of internal combustion engine engineering.

--=Motorhead 04:26, 15 Jun 2005 (UTC)