Ellen Feiss teaches diesel and Straight Vegetable Oil (SVO) theories of Operation
While Ellen Feiss is best known for her cunning ability to concisely describe PC problems and their solutions, she also holds expert knowledge in the operation and maintenance of diesel engines, and their operation with SVO and Waste Vegetable Oil (WVO) fuels. She was kind enough to pull herself away from her latest paper (and it was a really good paper) to give us a quick introduction to this subject.
Diesel Background
The diesel engine was first introduced by Rudolf Diesel, who received a patent in 1892 for his first design, which was to burn coal dust. After a few mishaps, he finally had a successful oil burning engine in 1895. Diesels belong to a class of engines known as compression-ignition, as opposed to the spark-ignition of gasoline engines. In a gasoline engine, the fuel is mixed with air before it enters the cylinder, where it is lightly compressed then ignited by a spark from the spark plug. In a diesel engine, air without fuel is compressed to a great degree (about 21.5 times in the 'vette), then at the top of piston travel the fuel is introduced, where it ignites in the high temperature environment due to the adiabatic heating in the cylinder during compression. Since there is less of a risk of pre-ignition than there is in gasoline engines, diesels can run a wide range of fuels, including diesel, biodiesel, kerosene, and vegetable oil.
Vegetable Oils and Diesel
Vegetable oil is very viscous at room temperatures and below, making it very difficult for the fuel injector to pump the oil through the lines to the cylinders. At about 80°C, the viscosity becomes comparable to that of diesel fuel 1. By heating up the oil before use, it becomes suitable for use in the existing fuel system. The 'Vette uses a double tank system to achieve this heating. The original diesel tank is still in place, and carries biodiesel or petrol diesel, or a combination of the two (almost always greater than 90% bioD!). A secondary 12 gallon plastic tank was installed for storing the WVO.Vegetable Oil Operation
The engine is started on biodiesel or petrol diesel from the main tank, and driven until operating temperature is reached. Lines carrying hot engine coolant (the green stuff in the radiator) are piped through a heat exchanger in the secondary fuel tank to heat the oil. The fuel line from the tank is carried to the engine compartment inside of Greasel's amazing Triple Bypass Hose, which heats the oil as it makes its holy journey to a better land. When the oil is warm enough to make it through the injector, a solenoid is activated via a switch on the console, which selects between the two tanks. There is no perceptible change in engine sound or power after switching. However, occupants may experience giddiness when they realize that they're being whisked along by waste oil, and no one's going to war over it. Before shutting the engine down, the fuel lines and injector must be flushed of vegetable oil, lest it cool down and become viscous. I shut down my 'Vette too early once and it was like "BLEEP BLEEP BLEEP BLEEP BLEEP BLEEEP!", and then, like, half of my injector was gone. and I was like..."ennnh?" If the oil in the injector gets too cold, it has to be heated up in situ with various ninja WVO ubertechniques before the engine will start again. Since you may not have these, always switch back to the biodiesel tank a few miles before shutting down, which will cleanse the lines out with nice healthy bioD.
QED
My name is Ellen Feiss, and I'm a vegoil enthusiast.
1 See http://www.oilpress.com/data-rape.htm for information on rapeseed viscosity vs. temperature data
( SVO vehicles are described in great length by many others. See the links page for examples.)
( SVO vehicles are described in great length by many others. See the links page for examples.)