Thursday, December 21, 2006



COCONUTS HILUX - How much fuel from which source has been used by the Coconuts Hilux?

The amount of coconut oil in the fuel blend of the coconut hilux has seen some interesting high and lows.



During the first peak to 10%, the fuel filter was replaced because water remains reacted with the coconut oil in the tank and subsequently plugged the filter. After two replacements of the fuel filter, this problem did not occur anymore. In the first period, cooking oil at US$1,5 per litre was used.

After the first drum of coconut oil was acquired, a more economic source of coconut oil was found at 0.6 US$/ litre.

This coconut oil had a great amount of particles and when this was put in the car in larger amounts (first peak over 60 percent), the internal strainer in the tank got blocked. Only after cleaning the tank twice, this was found and after cleaning this an adding extra holes, the engine operated back to normal.

Ever since then, I have been using a fuel filter before getting any fuel in the tank.
De-airing the fuel system was a major cause of problems after any alteration to the system.
Only recently virgin coconut oil that was slightly rancid was donated to me by a Pure Fiji, a local cosmetics manufacturer. While using this oil, I also included the fuel heater. This fuel heater worked very well and the exhaust had visually improved.

After a couple of days the injector pump started to leak significantly. Now the heater has been disconnected, the system stopped leaking, so it seems the hot fuel came through the gaskets of the fuel pump.
To be continued...

The amount of coconut oil does not seem to alter the mileage too much- it tends to be slightly lower with higher blends. Theory suggests that an engine requires 8% more coconut oil in volume than diesel - through its lower energy content and slightly higher density.

The graph to the left is a result of all the numbers the fuel I entered into the tank, placed in an XL sheet. It was a bit of figuring out how to calculate the blend. Think about it: you have 50 litres diesel, 5 litres coconut oil, 1 litre kerosene, you drive 200 km, add 30 litres of coconut oil. What blend are you left with? Anyway, I figured out a way with XL using the average mileage of the Hilux which approximates the blend in the tank pretty good. On the times that I had to empty the tank, I also had some nice reference points to check my calculations.

Now about the content of the graph. In the first period, I tested the 'waters' or better, the oil, as a slight addition to the diesel. No problems during that stage.

In the second stage, I obtained a big drum of coconut oil and started to increase the blend, utilising 15% vv of kerosene for each 85%vv of coconut oil whichever amount I added to the diesel. I had some starting problems (white smoke or very black smoke when it eventually started) and the problems described on "adaptations" with the strainer in the tank.
Around a 100,000 km I have been running on pure diesel, because the coconut oil I had in my yard was solidified and I could not get it out of the tank. Now the weather in Fiji has heated up again and I am up and running again!

Update December 2005

After the "winter" has passed and warmer times have come around, I have re-engaged my coconut oil pump and started to blend fuel again. I virtually stopped blending kerosene (note the area after 103.000 is mainly green / grey, no yellow base anymore.

Here is the reason: with kerosene, the injection pump will leak, without, it won't. The blend that is widely used in Vanuatu (15% kero, 85% coconut oil) somehow does not suit my car. According to biofuels expert, Dr. Gilles Vaitilingom, the blend with kerosene does not make more sense than trying to bring down the viscosity of the mix. He indicated that when the (kerosene) blend is injected in the cylinder, the kerosene will burn first, then nothing, then diesel will ignite. Therefore, the combustion process is totally different for what the engine is designed for.

Then, at 105.000, I got serious heating problems. I suspected the coconut oil had something to do with it, as I thought to observe an increased level in the oil sump. Reality was that my local lube-oil mechanic had put in too much... The heating problem was directly connected (it turned out later) with a problem in my cooling system. When I had fixed it, I again started to blend coconut oil in the diesel. The yellow area in the 107.000 area is my own stupidity: with a sleepy head I accidentally poured in 5.5 litres of petrol. It caused no problems and it will slowly disappear from the tank!

Update December 2006:

The last bit of yellow in the graph is a special Phillipino additive that I was given by the Fiji Department of Energy. It is produced by Tuks Oil and would assist in burning coconut oil. The content have been mysteriously unclear but I can tell you that my Hilux just smoked more. I cannot see any improvement, hence I stick with coconut / diesel blend.

My dear friends gave me a drum of coconut oil from the coconut oil mill in Savusavu for my birthday and I'm blending that with diesel now. Smells great!




Renewable Energy for Development

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