In the Autoblog Driveway: 2003 VW Jetta SVO (Straight Vegetable Oil)

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.

Full Circle Fuels in Oberlin, OH converted the Norton brothers’ “Vega Jet” to run on SVO by installing a pair of custom fuel tanks in the Jetta’s trunk. The Nortons must open the trunk in order to fill the smaller tank, which then automatically feeds a larger one fitted under the floor and around the spare tire. The system hardly reduces the useable trunk space, except for the SVO paraphernalia stowed back there to facilitate transporting barrels of veggie oil filled up at local restaurants.

Situated near the bay doors of the Turtle Plastics warehouse is a large storage tank for vegetable oil. The fuel is transferred through a tube to the car’s fuel tank via gravity since the storage unit is elevated above the dock in which the Jetta is parked. Before used grease from a restaurant is added to the storage unit, however, the Nortons must filter out any impurities using a filter bag. SVO vehicles can also run on fresh, unused vegetable oil, and Full Circle Fuels helped the Nortons score this pallet of expired cooking oil for around a $1.50/gallon. Remember when gasoline was $1.50/gallon?

We had a chance to drive the “Vega Jetta” on local roads and are happy to report that the experience was pleasantly ordinary. While the “Vega Jet” handles like there’s a hippy locked in the trunk due to the extra weight of the SVO tanks, acceleration and overall performance was on par with other diesel-powered Jettas we’ve driven. The only interior modifications we could find were the purge switch located on the Jetta’s dash and a fuel gauge custom-mounted in the door to keep tabs on the SVO tanks.

Although not much study has been performed on the emissions of an SVO-powered vehicle, they are comparable to what a biodiesel powerplant puts out, which is a marked improvement over that of a straight diesel. According to the website Energy Bulletin, there are no sulfur emissions, lower unburnt hydrocarbons, and somewhat lower carbon monoxide and particulates. While biodiesel has been shown to emit slightly higher levels of nitrous oxide than diesel, studies performed locally by Full Circle Fuels itself have indicated that running on straight grease emits less NOx than even diesel. SVO vehicles are virtually carbon dioxide free, as well, except for the small amount of CO2 released during start up or purging while running on diesel. Assuming one is careful about purging the vegetable oil from the vehicle’s fuel system, an SVO-powered vehicle will also enjoy the same durability as its diesel-powered countered thanks to the natural lubricity of vegetable oil.

Fuel economy also remains largely unchanged from a similar diesel-powered vehicle, which is to say these things will go great distances on a tank of grease. While saving money on fuel was an attractive quality for the Norton brothers, their reasons for burning vegetable oil are more closely aligned with the desire to use renewable resources that leave less of an impact on the environment than gasoline or diesel fuel, as well as the oft-cited hope that one day this country won’t be beholden to other oil-producing countries for its energy.

While this review was meant as a window into a day in the life of an SVO-equipped vehicle owner, we plan to return to the topic of SVO again in the near future to examine how the greasy technology fits into the increasingly varied mix of alternative fuels and powerplants. We’ll introduce you to Sam Merret and Bob Beckett, the two SVO-advocates that operate Full Circle Fuels in Oberlin, OH and perform SVO conversions on a daily basis. We’ll also examine Golden Fuel Systems, of which Full Circle Fuels is an affiliate of sorts. Formerly known as Greasel, Golden Fuel Systems is widely considered one of the best producers of SVO conversion kits in the business. Until then, we hope you’ll look twice at the bottle of cooking oil in your kitchen cabinet knowing that there’s a “Vega Jet” driving around looking for some free fuel to sip.

Related Links:
Turtle Plastics
Energy Bulletin
Full Circle Fuels
Golden Fuel Systems/Greasel

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