One lesser-known movement in green car technology is converting diesels to run on SVO, or Straight Vegetable Oil. Unlike biodiesel, which is produced by chemically modifying vegetable oil so that it can be used in a diesel vehicle with no modifications, SVO requires a second fuel system for the vegetable oil in addition to the standard diesel fuel system. Also, one doesn't operate and fill up an SVO vehicle like a normal petrol or diesel car. It sounds like a lot of work, so why are more and more people kicking up the veggie quotient of their diesels' diet? We decided to look into it.
No automaker offers an SVO-powered vehicle in its line-up, so tapping a press fleet for a quick evaluation was out of the question. Fortunately we stumbled upon Chuck and Tom Norton, a pair of sibs who run Turtle Plastics, an eco-friendly plastics business in Lorain, OH. The Norton boys recently had a 2003 Volkswagen Jetta TDi converted to run on SVO. Though Tom's the primary driver, Chuck was happy to hand over the keys to their "Vega Jet" for a spin last week and helped us understand what it's like to own and operate a vehicle that eats out of a dumpster. Let us explain...
Vegetable oil can be found in abundance throughout our daily lives. It's the can of canola or pint of peanut oil in the back of your kitchen cabinet. It's also the vat of boiling grease in which fries are drowned at your local family restaurant. People who own SVO vehicles often get their fuel for free from restaurants, literally taking it right from the grease dumpster out back. This gives SVOs their reputation as dumpster divers, but it also means an SVO vehicle can potentially pay for its $2,000-$3,000 conversion in less than a year thanks to free fuel. Owners shouldn't count on free grease as a given, but America's appetite for fried foods knows no bounds so the supply seems virtually limitless.
Before we dive deeper into the question of why someone would choose to convert a vehicle to run on SVO, let's go over exactly how it works. While modern diesel engines require no modification to burn vegetable oil, a separate fuel system is required because SVO takes on the viscosity of a cinder block as the temperature drops. On account of this, a diesel fuel system is still needed to operate the vehicle until the SVO can warm up and thin out.
Though each installation is different, an average SVO conversion involves adding a separate fuel tank, filter and fuel lines for the vegetable oil, as well as modifying the coolant system to transfer the engine's heat to these new components. On the Nortons' Jetta the fuel lines carrying SVO up to the engine are cleverly packed with coolant lines that run all the way to the SVO fuel tanks custom mounted in the trunk.
At startup the "Vega Jet" will run off of its diesel fuel system until the engine has warmed. Normally that heat energy would be lost via the car's radiator, but this SVO vehicle reuses the heat thanks to the modified coolant system that quickly thins out the vegetable oil so it can flow freely in the system.
After about five minutes of operating on diesel the fuel systems can be switched and SVO can take over combustion duty. The two fuel systems meet up front under the hood where a solenoid is activated via a dash-mounted switch to change between the two. From there the two fuel systems share a fuel line for a short distance, usually about eight inches. The Nortons need to purge that line of vegetable oil if they're going to leave the car to cool down after being used. This involves simply switching back to diesel fuel for the last five minutes of a trip. If vegetable oil were left in the fuel line to cool and congeal, it would block the flow of diesel on the next start up.