Bob,

An excellent summary of the timeline! Thanks!

There are a few other differences, between designed-as and your excellent diesel-conversion types.

I go on and on, occasionally, here and other sites, about the (?) "port volume" (?) conditions for glow or diesel fuel use. In short, as I see it, glow fuels, based on methanol and glow ignition, are extremely tolerant of rich mixtures.

1) Methanol can - usually does - vaporize well in the intake flow. Kerosene-based diesel fuelsprobably donot do that as well, and kerosene has a much smaller tolerance for rich mixtures. These ideas allow glow engines to have relatively LARGE bypass volumes - the vaporized methanol stays vaporized. And it will still burn at very rich fuel/air mixtures.

2) Because of 1.), above, most moderate RPM, designed-as, diesels I've been inside of have quite small bypass channels. They are large enough to do two things - first, they CAN supply enough air/fuel mix to the combustion side at the moderate RPMthe engines seem happy at, and second, the small channels keep the flow speed up to where the kerosene, whether vaporized or in the form of extremely small droplets, doesn't get a chance to slow down and collect into larger droplets. Vaporized fuel, or very-fine-droplet mixed fuel burns better than a smaller number of large globs...

3) Again, referring back to my opinions in 1.) and 2.), above, all our model engines are essentially air pumps. For methanol-based fuels, we can get away with, and gain from, overly rich settings. Methanol will still burn productively at very rich settings. We can rev out, gaining horsepower, quite a way past torque peak RPM. Kerosene-based fuels, for one thing, cannot burn well, if at all, at excessively rich settings, and for another- with the higher compression ratios needed for "diesel" combustion, there isn't room in the combustion chamber for large globs of liquid fuel. Can you say: hydraulic lock?
____SO, the ability of the engine to pump air works with methanol for more horsepower at higher RPM, but limits the amount of kerosene-based fuel it can burn...

4.) All this aside, the "diesel" system is tolerant enough of wierd conditions that the designed-as diesel runs well, economically and strong at around torque peak RPM (where the volumetric efficiency of the engine is at max.) The diesel ignition is also tolerant enough of things that your conversions of the over-breathing designed-as-glow engines do fantastically well - running well, economically and strong at torque peak RPMand somewhat above. (And, with appropriate props, can pretty well match any glow engine performance as long as we don't go too rich with kerosene.)

ASIDE: In CL Stunt, engines like the classic Fox 35, have been "improved" by blocking-off part of the bypass volume. That keeps the bypass flow speed up, for more turbulence (i.e., better mixing of the fuel-air charge), and makes it less sensitive to g-loading effects (remember- fixed throttle, no carb, g-loads from 1.0 to perhaps 30g.) I wonder if there would be any effective gain for one of your converted engines to do something similar to an over-generously ported designed-as glow with your conversion head? If so, I'd guess it would mean more stump-pulling torque around torque peak RPM. rather than an extended RPMrange.

They are a bit different, but both approaches work - as-designed and head-converted diesels, for one, and glow and diesel engines, for another.

Glad you're still making it easy, simple and successful for so many glow-engine users to learn that diesels don't smell bad, just different...