Scott:

I am perplexed by the tone of your response.

** 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.**

I was speaking to the gap of the spark plug, not in a magneto. I sure am sorry that I didn't make that clearer or that you misunderstood that. Your aggressive response seems overreactive.
 
**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.**

The warm fuel lines cool very, very quickly as cool fuel runs through them. They are not the reason a hot started engine fails after the initial firing. It's the heat-soaked fuel pump which has a fair amount of metal mass and is more difficult to cool off. It's not vaporized fuel in the lines that the pump cavitates on. It is the heat of the pump itself which causes the vaporization that results in cavitation and vapor in the lines downstream of the pump.
 
**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.**

There are any number of things which are frequently misunderstood about timing by the average bear. This may be one reason we have a growing file of engine problems so related from owners making incorrect assumptions about the effects of timing changes. You are clearly knowledgeable in this area, but there are lurkers on these lists who may not have that same level of understanding and a cautious approach to these changes may be a good thing. As I have stated before, at high power settings even small advances in timing can result in large changes in stress in the cylinder while those changes have little effect on HP. At lower power settings this is not the case. If an electronic system has a hotter spark (which is fairly well appreciated) it has the result of advancing the effective timing and the thetaPP. It could well be that setting the same timing for takeoff as a mag using an electronic system is not the optimum thing to do. Retarding the timing of that system would result in lower stress and higher HP. I am sorry if those facts upset you.
 
**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.**

It's nice that you acknowledge the science.

**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. **

Who has suggested otherwise? I haven't.
 
**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.**

Who has suggested otherwise? I haven't. Your tone is a puzzlement.

There are some very interesting harmonics which have been measured on crankshafts on engines with EIs. What do you know and what can you tell us about crankshaft harmonic effects as a result of electronic ignitions... and why they are being observed when they are not observed in engines with less efficient and antiquated magnetos? Please tell us. I'm affraid that if *I* do so, you will be upset that I'm "carping."

I subscribed to this list because a couple of the members asked me to come here and try to enlighten some of the misunderstandings that seemed to exist concerning engine management. It's all yours. I have other things to do. If anyone has any questions, you all know how to contact me.

Walter