After extensive R & D, we finally have a substitute for ether. That substitute is none. No, I don't mean that there is no substitute, that means that ether is NOT essential as an ingredient in diesel fuel for model engines.
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Success with the 5% ether fuel led me to try a fuel containing no ether at all. This consisted of 20% castor, 80% kerosene and 2% Amsoil cetane booster. Yes, this doesn't add up but describing it this way makes it easier to visualize the percentages. Unfortunately, I didn't take note of the compression and needle setting from the 5% run but with a little persistence, the engine lit off and ran. It took maximum compression and a needle valve a half turn richer to get it going. How? I made up a PRIME mix of 50% ether, 30% kero and 20% oil.
It took 5 to 6 prime bursts until the engine's cylinder got hot enough to allow a rough run. As the cylinder warmed, the compression was backed off giving an increase in power. The needle was then turned in and the compression brought in a bit.
The result is a nice, solid run as you see. Power is on par with fuel containing ether in whatever percentages. The ONLY issue with a no ether fuel was getting the engine hot enough to run.
Also, idle and transition became a little spotty. Still, the idle held and no flame out resulted from cracking the throttle open. It appears to go rich at idle even with the airbleed screw backed off all the way. Modifications to the throttle to allow for a leaner idle will be applied.
As in all cases, a start was affected by applying three to four drops of prime into the intake. Then the starter was applied. Again, the prime was a special HIGH ether mix.
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Next was an attempt to eliminate the need for a relatively special oil that might not be readily available. Fuel was 20% #50 weight motor oil, 80% kerosene and 2% Amsoil cetane booster.
In this case, the engine would NOT start even with a dozen or more prime runs. What it took to get it to keep running after a prime burst was to FIRST heat up the engine with a heat gun. That did the trick, a prime burst or three and the engine caught and kept going. The compression screw, once again, was to the max and the needle was backed off a half turn.
Power is down from the castor/Amsoil mix. Could it be that the superior lubricity of castor enhances power? Could it also be that the superior lubricity and subsequent better compression seal of castor oil made starting more easily accomplished?
Idle and transition was on par with the first, no ether fuel.
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Finally, here was an attempt to get a diesel to run on ingredients you can find at your hardware store and/or your automotive outlet. No need to order the Castor or the Amsoil cetane booster. Here we had a mix of 20% #50 weight motor oil, 80% kerosene and 2% MEKP.
As with the Amsoil mix, it required the assistance of the heat gun to get a prime burst or three or four to get a run that held. Again, the compression screw needed to be backed off and the needle dialled in. In this case, with the MEKP as an ignition improver, the compression needed to be a bit tighter to get a good run. And, starting was a bit harder.
The conclusion is that Amsoil is a better ignition promoter than the MEKP. Still the latter does work well on a fuel containing the usual, substantial amount of ether.
As with the other two, no ether fuels, idle and transition was less than the best but was acceptable. Likely to be improved with some throttle modifications to allow for a leaner adjustment at idle.
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Amazingly, despite all that is known about model diesel engines, this Norvel ran with NO ether in the fuel. None, whatsoever. Once running, as the engine came up to operating temperature, the engine ran well. I have no temperature gauge but subjectively, the engine seemed to run hotter than with glow or with an ether based fuel. Not so hot though, as to exhibit any overheating symptoms. In any case, the Norvels have significantly more cooling fin area than most engines. The next experiment will be to turn down the fins to see if the need to apply the heat gun and/or the tighter compression to start can be minimized or eliminated. Diesels, after all, are said to NEED heat to run and this experiment certainly seems to prove that out.
I propose a challenge to all. If you have a Norvel .15 converted to diesel, give this a try. If you have an MVVS .15 or a converted .15 whatever, and if you are adventurous, curious, and dislike paradigms, give it a try and let us know how you make out. Do use a small starter and ONLY prime into the intake. Cinch up the compression to start, with the needle out a bit. Back off the compression right away as needed. Max out the needle and observe throttling performance. If no starts can be affected with just prime runs, do apply the heat gun,,, as hot as it'll get. Give yourself the best chance by using castor and the Amsoil or, if your lucky enough to have it, real amyl nitrate.
Again, there may be something unique to a Norvel engine's metallurgy that enhances its ability to perform as a diesel. On the smaller engines, though, low ether mixes were tried with poor performance overall. The larger engines seem more tolerant to low or no ether.