[Diy_efi] Timing Advance Curve?

[Mike]

At 03:20 AM 22/12/2002 +0800, you wrote:

>As I understand it; the gas movement prior to ignition adds to that
>of the flame front; hence high "swirl" rates appear to reduce
>detonation because they "outpace" the thermal transfer to the
>end-gas so that it's less likely to detonate. The flame-front is
>"swept" through the combustion chamber at greater speed (up to 80
>metres/second IIRC); about the same order of magnitude of the flame
>front velocity.

Now this is an interesting point, is there an asymptotic limit
in repsect of chamber geometry variables and implementation
which might well quell the vast majority of detonation like
incidents in line with the paradigm you describe in your para above ?

I recall reading some years ago about a chap "Smokey ..." in US
who had built a 4 cylinder engine which ran a really high intake
manifold temperature - somewhere between 250 - 350 F. I recall
he had a turbo (which he said he used as a one way valve), used
a carby inside a hot water jacket and I think used exhaust gas
to heat the intake manifold - yet did he get detonation (?), well
he said not and confused the hell out of visting motor co
execs by burning his hand on the said intake manifold <mmmmMMMM!>
I also recall he stated his chamber design/layout was of some
importance but, thats the limit of my memory on this - must have
been 10-15 years ago - anyone know of this ? ?

<snipped>

>I'm sceptical of the "spontaneous" explosion inference. More than
>likely; the supersonic detonation process is either simply too fast
>to be captured or is too destructive on the flame front.

Yeah thats what I'm guessing as well, and the reflections of this
prcoess (amoung others) causes the ping we readily hear.

>The only thing I can't explain right now is why I'm writing this at
>3 a.m. on a Sunday. :-(

Or why I am on so many lists <sigh> and didnt get a Sat night date :(

rgds

mike



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