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Hi Gord,
Yep...very good Friedrich...that's exactly as I see it...one point, you use the term 'preignition' and although I see how you meant it now (and you're correct) I never use that term unless I'm describing the occurance of spark, it can be confused with that.. possibly my mistake - I'm not a native English speaker. What you described to me would have been "ignition advance" - the crank angle before TDC when the spark occurs. What term would you use for occurence of ignition before flamefront or before spark? "Detonation will be evidenced by a rapid rise in cylinder head temp, a rapid rise in oil temp, a rapid drop in torque closely followed by structural parts of the engine emitting from the exhaust stacks" LOL! (not that it's funny when it happens to you in flight...) I think they used that to scare the snot outta us engineers (it worked too!) Not so much on us automotive engineers today... A lot of modern automotive engines are run right along the knock limit for efficiency, with knock control constantly operating. To do this, there has to be a knock event every now and then for the knock control to be able to detect the limit. (Knock control just detects knock events and retards the ignition. When there is no knock, ignition is advanced again until the next knock occurs.) This normally works fine. However on some (not all) engine types, on high load testbed runs this has recently led to very rare statistical occurence of "super-knock" events, with disastrous results. I will be interested to see, how the proposed GAMI PRISM system is going to work in this respect. As far as I understand it, the knock detection principle is much more advanced than what you can afford on an automotive engine (something about continuously measuring the cylinder pressure), but there still has to be the occasional knock for the system to know where the limit is. regards, Friedrich -- for personal email please remove "entfernen" from my adress |
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