Re: Knock/advance

[Jonathan Coates <cdico.demon.co.uk@cdico.demon.co.uk>]

In message , Robert A Brady <Robert_A_Brady@rohmhaas.com> writes
>Knock is synonymous with detonation.  Strictly speaking, a detonation is 
>different from a deflagration (typical "burn") in that the flame front is 
>supersonic.
Could you explain why you call it a flame front? From reading
descriptions of the mechanism of knocking I understood the mixture to
reach a condition where the entire "charge" of fuel/air mixture burns at
the same time. If this is the case, there should be no flame front as
such.
>We've also all experienced the 
>phenomenon of knock occurring under low rpm with wide open throttle.  I'll 
>have to think about that one a bit to explain why it occurs... but not 
>today.
As I understand this phenomenon, which is probably wrong, the low RPM
allows the cylinder to fill more completely as the inlet valve is open
for a longer time and the pressure drop from atmosphere to cylinder is
lower due to lower gas velocity.
-- 
Jonathan Coates
164LV6 Daily driver
752.0TS T car
Alfetta 2.0 GTV Veni Vidi Visa