toy-bus-200.jpgLets talk about the diesel engine and what happens when fuel is run through it. You might want to run diesel fuel in your diesel engine or you might choose a vegetable oil or fat to run through it. Running WVO or SVO is what we call a grease car. Your fuel runs through the injector system which is designed to deliver and properly atomize diesel fuel. Atomization is conversion of bulk liquid into a spray or mist (i.e. collection of drops), often by passing the liquid through a nozzle. When running SVO or WVO through the injectors the viscosity has to be lowered in order not to damage to engine. Diesel fuel has the viscosity of around 8 centistokes. WVO or SVO has a much larger viscosity of 10 to 20 time more. You are trying to run that through an injector spray jet made for fuel with the viscosity of 8. Now this will create an improper spray pattern and cause damage to the engine. Your fuel will not have a proper combustion when the spray pattern is wrong. You will have to lower the viscosity down.

The other issue which needs to be dealt with is the polymerization of vegetable oil when it contacts metal below an optimum temperature. Imagine placing a skillet on the stove, pouring a small amount of vegetable oil in the skillet, and turning the heat to high. The skillet will begin to heat up and as it does it will heat the oil, around 300F the oil will start to smoke, then turn black, stick to the skillet, and destroy it. With another skillet on your stove, turn the heat on high again. When the Skillet gets to about 600F throw a tablespoon of oil in the Skillet, You will notice that the oil is skittering around the skillet on a layer of vapor, none of the oil is sticking to the skillet and none of it is turning to carbon.This same principle applies inside the combustion chamber of your engine, so injecting oil at any temperature into a combustion which is not at operating temperature will result in carbonaceous deposits being formed on the piston crown and cylinder walls again destroying your engine.

So when you are setting up a diesel engine to run as a grease car you will have these two major obstacles mentioned above. You can run vegetable oil without changing a thing and it will probably work but in time the engine will be damaged . So just keep these two things in mind.
1) The vegetable oil must be heated to at least 160F before being injected so that it can be atomized properly by the injectors.
2) The engine must be at operating temperature before any oil is injected.

Frederick Carter

Semi retired at 50 yrs old. I’m fascinated with new sources of energy and am always working on new projects. The grease car is one dear to my heartMyschool bus conversion is on track.

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