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Post by Jonathan Smith on Oct 8, 2005 9:53:42 GMT
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Post by fredwhitworth on Oct 8, 2005 15:19:00 GMT
Jonathan wrote: "http://www.rodbowen.co.uk/daniel/home.htm "
__. I've been looking at these conversions and I expect to go over to one within the next few months. But there is one important issue: -- Vegetable oil is significantly thicker than petro-diesel and this viscosity difference gets greater as temperatures drop. Besides the usual problems of gelling/fuel starvation at lower temps, which are made worse by veg fuels, veg fuels are not suitable for being pumped through automotive fuel injectors. Injectors and injector pumps suffer increased (and sometimes catastrophic) wear with veg fuels and often see disabling deposits. Also, the veg fuels don't spray or atomize very well as they're being sprayed from the injector. Not only does this give poor running, this results in the globs of fuel failing to burn properly, resulting in coking problems in the combustion chamber. This would be bad enough but the coking seems to be worse (and most damaging) at the upper piston rings. Rings so coked up will stick, resulting in blow-by of combustion which burns oil off the pistons and cylinder wall and complete seizure of the engine follow quickly.
__. All these ill effects can be avoided by heating the veg oil fuel to a temp of about 180degrees F. That's what the "conversion" kits do. Of course, some injector pumps and injectors do a better job of keeping the fuel warm through the distribution and pumping process so success varies between different types of engines.
__. Most of the conversion kits are based upon the principle of having two fuel tanks and distribution systems. With these conversions, the engine is started and warmed up on petro-diesel. When the engine coolant is fully warmed, veg oil is passed through a radiator-type heat exchanger. As the veg oil reaches it's optimal temperature, switches or valves cut off the supply of diesel fuel and change over to supply of heated veg oil. The fuel valves must be reversed so that diesel is circulated back through the injection system before shutdown so that the system is primed with petro-diesel before the next startup.
__. Also, operation in colder temperatures varies between systems. In some cases, it's just not possible to switch over to veg fuel in some winter conditions -- in this case, one must continue to run on petro-diesel fuel.
__. The website offers to sell taxed veg oil. However, it's important to note that restaurants, chip shops, etc. are often anxious to dispose of used frying oil -- they usually have to pay to have it hauled away. These used oils are contaminated with solid materials from the foods cooked and also water but it's a simple, cheap, and easy process to filter and dry this used oil into a clean oil for use in veg fuel engines. Thus, except for duty and tax, this fuel is very low cost.
__. Well designed and executed conversion systems can give excellent results - in fact, these engines make less soot (resulting in less load on the oil and resultant improvement in engine wear) and give better emissions -- aside from the cost advantages of running veg oils. However, the process is critical and the fuel supply and distribution system used in the conversion must give optimal performance. As the technology is in it's infancy, one is really experimenting with the engine in his bus. So, it's not without risks, but the benefits are great.
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Post by busboy on Mar 16, 2006 19:57:28 GMT
Well funny stuff, I offer this opinion: My landrover runs fine on 2/3 rape seed oil and 1/3 diesel. This is without any conversion of the engine or fuel system. It works fine but kicks out a little bit of soot and eats fuel filters a bit faster. I can't really see a problem with old diesel engines working in this ratio, unless they have fance things on them like turbo's.
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Post by crizzzuk on Jul 30, 2010 22:47:46 GMT
Mmmmm Ive used 3/4 recycled cooking oil 1/4 diesel in a number of vehicles with no conversion over the last 10 years and never had a problem(iveco 2.8 turbo daily,mitsubishi pajero,landrover 90 td,vw transporter,nissan navara and a daf duple. So not sure I agree with this tread
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