HIgh altitudes increase the voltage required to jump the gap on the plug.
 
  Also, vapor locks are not in the fine lines above the engine during a hot
start.  The hot start problem is a result of the vapor locking in the heat
soaked engine driven fuel pump.  Cool the engine driven fuel pump and there
are no hot starts.

Walter,

 

Yes, of course Walter.  That's why magnetos used at high altitudes are pressurized - Not.  They are pressurized to reduce the point arcing that occurs when there is less of an air insulator.  If you have a reference, please point it out as I am always interested to learn which truth is the truth. 

 

It is easy to cool the engine fuel pump in TCM style engines with return lines, just run the boost pump for a while to circulate cool fuel before attempting a hot start.  I will agree that the heat soaked engine fuel pump cavitating on vaporizing fuel is often why those without throttle body to fuel tank return lines have so much trouble.  Trouble usually overcome by utilizing the ever important boost pump in order to force enough fuel thru to the throttle body or raise the pressure high enough to reduce the vaporization.  However, the problem is exacerbated by vapor in the spider to injector lines and its re-vaporization after a shot of boosted fuel.  Most of the time a carbureted engine may have enough fuel in the bowl to more easily initiate a hot start, the actual point I was trying to make.

 

Side bar:

 

I have not responded to any of your previous remarks about Electronic Ignitions because, as usual, you only provide worse case generalizations, negative comments and little useful information from a practical application viewpoint.  There are many of us that are quite successfully using such EIs and all of us realize that badly mistiming an engine can lead to its destruction (we know this as a result of your constant carping).  EIs do not destroy engines without either a system failure or mismatching the timing curve, if any, to the engine and its operating environment.

 

Maybe I should just spend more time qualifying my remarks even more than I do now?

 

The best point you make is that the optimum peak pressure is to be delivered at a certain crank angle, relative to the piston position in the cylinder, after top dead center (16 degrees?) for engines with opposed cylinders.  Peak pressure at other times may only result in less efficiency, such as a consequence from fixed spark initiation timing while other operating environmental conditions have altered the length of flame propagation, thus the timing of the peak pressure.  Some of us, flying rather than studying lab engines, have learned to appreciate the additional HP, reliability and efficiency delivered by modern electronic ignition systems regardless of the varied implementations extant today.  We are not destroying our engines. 

 

The fact is that EIs provide great benefits for the spark, thus flame initiation, even if only fixed timing is used (I.E. a selectable operational mode on E-mags).  The fuel efficiencies gained when operating below 70% power are proven, even if not as well documented as everyone would like.  Even PRISM is merely an electronic ignition with a different, more sophisticated control on the spark initiation while also promising the benefits of a better spark, etc.