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Old 9th Oct 2018, 08:59
  #80 (permalink)  
rutan around
 
Join Date: Jul 2005
Location: Queensland
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AEFR
If ignition timing were drastically incorrect, i.e. too far advanced, detonation would be the immediate result.
Not necessarily. If the octane rating of the fuel is high enough it won't detonate. However if the timing is too far advanced ie the fire is lit too early all the fuel will be burnt at or even before top dead centre. This means peak pressure occurs early and, at first, is doing negative work until the piston is past TDC and can begin to move down and do some useful work. The lengthy time (relatively) that peak pressure (and high heat) are in the cylinder's head transfers much more heat to the enclosing metal before the valve opens and dumps the exhaust gas and cooling can begin. It is the heat doing the damage.

How did you address the problem of different flame front speeds for the different fuels?
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