Veggie Oil Heaters

If you were to operate your car for sustained periods on cold vegetable oil, your injector pump would have trouble pumping it and eventually fail, your injectors are likely to clog up and spray incorrectly, you will get coking in the cylinder bore and you may require major and expensive work to be done to your engine.

To avoid this, the industry all agree that it is best to use vegetable oil when the engine is hot, and simply heat the oil to at least 70°c before it reaches the injector pump.  There are many ways of heating the oil.  You can use a coolant heat exchanger, an electric fuel heater, or a combination of the two.

Some people heat the entire tank of fuel by installing coolant lines through the tank or installing a “hot rod” which heats the fuel using coolant at the uptake point. These systems are necessary for use in very cold climates and are particularly useful for tallow as it goes solid in your tank and fuel lines.  This takes a long time for your fuel to get hot enough to use, and often requires some major modifications to the tank.  In our warmer Australian climate, I prefer a system of an inline fuel heater, so you won’t have to modify your tank.  

In my original conversion, I used a reasonably inefficient 32amp 12volt inline fuel heater.  The upside to this unit is instant heat – you don’t have to wait for your coolant to get really hot before you switch to WVO.

The downside is that it’s cold where I live in the Dandenong Ranges of Melbourne, and without a heat exchanger, the heater was using the full 32amps to heat the oil, with most of the heat generated being lost to the atmosphere. As a result my 60amp alternator burnt out on a long trip home one cold wet night.  When you add up the rest of the electricity needs of the vehicle, I didn’t have any power left for the fuel heater.  Thankfully we now have 12 volt fuel heaters that are more efficient.

For a small car you can easily make a coolant heat exchanger by wrapping a coil of 6mm copper pipe or fuel hose (preferred) around the top radiator hose and then lag it with insulation such as an oversized radiator hose or high temperature foam.

A friend’s car has a tin can that has coolant running through it from the heater hoses.  He has a 6mm copper fuel line wound into a tight spiral in the can, then the whole unit has been insulated.  This brings the fuel temperature up to 1°c less than the coolant by the time the engine is at operating temperature.

One of my customers has modified a heat exchanger used in the bottom tank of some radiators to cool transmission fluid.  These are available from radiator repairers, and are very inexpensive.

Another idea is to run the fuel return line back into the fuel up line before your fuel filter.  This helps the fuel filter heat up quickly, allowing better flow of fuel, and also increases the efficiency of any heater that you may be using, although can make it more difficult to bleed air out of the fuel system.

I didn’t think that the little alternator in the Tarago would handle a  32amp heater very well, so I explored other options and used a coolant heated fuel processor that incorporates a heat exchanger in the head of the filter.  This fuel processor is intended for use in diesel trucks in very cold places like Canada, to eliminate waxing in sub zero temperatures, so they are not sold in Australia.  I imported some and removed the thermostats to run them at much higher temperatures.  I have combined this with a 16amp electric heater so that it only draws power for a little while but maximises my ability to use vegetable oil.

You can pick up a professionally manufactured heat exchanger from a recreational vehicle shop, but they are often similar in price to the heated filter units that offer a dual use. (see Fuel Processors)

Vegiecars now offer inexpensive plate heat exchangers that can be fitted to the body of the vehicle and get the temperature up very quickly.  Similar plate heat exchangers might be found at home brewing (beer) supplies shops.

In the following pages I will outline various options for you to convert your vehicle.  There are two systems, a no purge or single tank system, or the more common dual tank system which is the traditional method of converting and is more reliable.