The current system I am using has evolved over about ten years and three vehicles. I shall detail here a distillation of all the tips and tricks that I have found works best for me and my engine. One thing I found out very early on during my research was that there are many different opinions and ways of running a vehicle on Straight Vegetable Oil (SVO). I do not claim that my approach is the best or the correct one, but as you will see, the results seem to suggest that I am not too far off. However please note; I cannot be held responsible for any damage to anybody’s engine as a result of adopting anything detailed here.
I will be honest straight away and admit the main reason for me converting to SVO was money. All the oil I use is waste oil collected from restaurants etc. I have been able to get this for free and since the Government dropped the need to pay fuel duty on usages below 2500 litres per year it has saved me a fair amount. However it is also very satisfying to know that the majority of the fuel I use is not a fossil fuel and is carbon neutral.
The basis of my system was a kit from Dieselveg a company in Wolverhampton UK. Online research told me that they are one of the most popular choices. I was not disappointed with the kit. It was good quality and the service offered by the company was very helpful. The kit consisted of a heat exchanger, 2 x changeover valves, inline filters, pipework and all the necessary switches/relays/wiring. They have since added a controller for the system. As a special offer the kit also came with a quick purge device, more on that later.
To help understand the reasons for the route that I took I have shown here a diagram of the fuel system for my engine. The engine is a 300Tdi 2.5 ltr diesel. The fuel tank is situated under the driver’s seat and from there the fuel line goes to the mechanically operated lift pump. This then delivers fuel at low pressure to the fuel filter and then on to the injection pump. The injection pump is a Bosch VE rotary pump with a diaphragm manifold pressure compensator. These pumps are the best at withstanding vegetable oil use. They have an inherent strength that will tolerate a small amount of cold vegetable oil but I wouldn’t recommend putting it to the test too often. The leak off from the I.P. and the injectors is then fed back to the tank via the return or spill pipe. Being a short wheelbase Defender, my vehicle does not have a sedimentor. These are fitted to Discoverys and 110s.
In the next article to come, I will detail how I fitted the system and the additional items I have fitted since.
