The Vegan Bus WVO (Waste Vegetable Oil) Conversion

The Vegan Bus was originally converted to run on waste vegetable oil (WVO) in August of 2007, about 2 weeks before we drove it on a 6,000 mile cross country trip to Burning Man and back. Our mechanic is Wendell Rheinheimer, who had previously converted several cars and one short bus. For this conversion he used a prototype kit made especially for large diesel engines created by our local WVO conversion experts at Greasecar.

The basic nuts and bolts of any WVO system are outlined on the Greasecar site:

The Greasecar system is a two tank fuel system. The vehicles existing diesel tank and filter supply diesel fuel to the engine at start up and shut down. After start up radiator fluid will transfer heat from the engine to the heat exchangers in the fuel system. These heat exchangers will heat the vegetable oil in the fuel filter, lines and fuel tank. The heat will reduce the viscosity of vegetable oil so that it is similar to diesel and can be injected into the engine properly. When the vehicle is being shut down for a period long enough for the fuel to cool the vegetable oil must be purged from the fuel system and replaced with diesel for the next start up.

As you can see, the original diesel tank is left in place and a second tank for the WVO is added. In our case it is a 40 gallon tank. The way that the system works is that we start the Vegan Bus on diesel. We have an on-board computer (called the "Co-Pilot") which controls the valve which switches between diesel and vegetable oil.

The computer can run the switching process automatically, but we prefer to have control and run it on the manual setting. Once the bus is started the computer displays that we are running on diesel and tells us what the temperature of the engine is. Once we get the engine heated we switch to WVO and the computer tells us how much fuel we have in the WVO tank. When turning the bus off we purge the WVO from the engine and refill it with diesel, so the WVO doesn't coagulate in the system. The computer counts down the time that this takes for us, and beeps a warning if we shut down without doing this important step. This can all be done in a system without a computer of course, but we got it at a discount price and it makes it a bit more fun!

The essential part of the system is the valve which acts as a switch between diesel and WVO. As we stated above we have a heavy duty one made for large engines, and of which we were one of the first to test for Greasecar. Here is a photo of it installed on our bus:

The oil in the WVO tank is heated by engine coolant (radiator fluid) which is pumped into a copper coil in the tank, warming the WVO to a high enough temperature to reduce its viscosity enough to run through the engine. With our system the fuel is transported to the engine in a plastic pex tubing which is encased in a larger rubber radiator-type hosing which surrounds the fuel with heated coolant and keeps the WVO hot all the way into the fuel injectors.

Hoses going into the Vegan Bus WVO tank

Keeping the WVO warm and at a low viscosity is very important, but of equal importance is making sure the fuel is clean and doesn't clog the Injector Pumps going into the engine. Part of this process is pre-filtering the oil. We are currently revamping this part of the system and will talk about that in a subsequent post. There is also a filter installed in the WVO fuel line just before it goes into the Injectors. This filter is a 10 micron high volume fuel filter that is wrapped in a copper coil to keep the fuel warm.

At this time our bus also has 2 extra 55 gallon drums for storing extra WVO, and a 20 gallon per minute pump that runs on 12 volts and helps us extract used oil from grease dumpsters while we are on the road. One of our 55 Gallon drums, which was donated by the Florence Casket Company