Ugo, I'm not sure what this means can you use other words? Wait the wonderful world of the internet gave me the answer. I'm still not sure what you are saying and exactly what it is regarding. HCCI combustion has not been studied in the way we must use it in our engines. We must mix lubricant even in our four strokes. This is a limitation that the existing research can't answer. I can't even begin to get the answer I would like to have. What is the actual percentage of fuel being burned? I estimated that my FS-48 conversion running on 20% castor oil, 78% kerosene, and 2% octyl nitrate is running at a Lambda 0.8 not including the oil. HCCI research rarely included anything less than 1.0 Lambda and goes all the way to 5.0 typically. I can't even directly measure Lambda because of the oil in the fuel. I'm seriously considering creating a mist lubrication system for a four stroke so I can burn fuel without lube. Combustion chambers are small in these engines so there is little we can do, and few have tried changing anything. Carbs are carbs to most people. Andy knows this is not true which is why I ask about the vaporization aspect of running a heavy fuel. Anyhow I was about to try running a 15% oil mix when I ran out of time and weather. As with vaporization, I didn't check an ether based mix, but I will. I wonder if the kerosene doesn't fully burn even if there is ether in the mix.

There is a difference between running an antique irreplaceable engine with a fuel of unknown properties and developing an engine around a fuel you want to run. I am more inclined to modify, or build an engine for this purpose rather than just replace the fuel for existing engines.

Serious team racers (FAI F2C) run a minimum amount of oil. I understand that those who can afford it in engine wear run 10% castor oil. This is to allow the greatest amount of combustible fuel to be carried in the fixed size tank.

The original intent of this thread was to reduce the cost of fuel and increase accessibility by using commonly available products. The main problem was ether, which is expensive and hard to obtain. Kerosene is commonly available and many of us decided it works well with some additives. A small percentage of ether improves starting and handling considerably. Actual fuel consumption was not even mentioned by anyone other than Andy, Treven, and myself, so I don't think efficiency is really a concern, or we would all be using four stroke engines. Ether is expensive and hard to get in most developed countries, that's why we want to eliminate it. Ether does improve idling and makes starting very easy.

I disagree that the cost of the engine is the most important in economy as this depends on engine cost. We can buy Chinese engines of good quality for a decent price. If we are burning conventional model diesel fuel in that engine at 25+USD per gallon, we find that fuel cost is greater than engine investment after 2 gallons or so. Our engines would have to wear very quickly to make this a problem. Etherless mix is less than half of that with castor oil, and far less with regular crankcase oil. Or if we did what Treven does, oil would be essentially free. There is, of course, no sense in wearing engine components needlessly. Perhaps your oil modification experiments will lead to a superior lubricant that we can make at home. Olive oil isn't exactly cheap though.

So what is my goal?

1. To burn a mix of kerosene or pump No.2 diesel, lube (whatever works, preferably purchased), and ignition improver that is readily available but not ether.
2. Design or modify an engine that will start and run reliably on the above fuel mix.
3. Optimize the engine to be as efficient as I can. This means reducing the fuel and oil consumption to a minimum.