May the long time sun shine upon you, all love surround you and the pure light within you, guide your way on "~Incredible String Band

Monday, April 04, 2005

The Lowdown on the Veg.,,

Howdy folks, Moss here. I will be getting you hip to the ins and outs of our conversion proccess.

As stated by miss Pix, the main thing is to heat the oil to the proper temperature so's it is the right viscocity to flow properly through the engine. To do this we use the coolent.

Under normal circumstances the coolent leaves the engine after absorbing as much heat as it can and goes to the heater of the vehicle. From there it makes its way to the radiator,where it is cooled, before going back to the engine where it starts the cycle all over again.

What we did was rerout the coolent through a copper pipe, surounded by a larger metal pipe. As the coolent in the copper tube flows toward the second fuel tank, the veggie oil in the tank flows toward the engine through the larger metal pipe. The hot radiator fluid heats up the oil going to the engine. This is called a tri core heating system.

In our conversion, we let the coolent in the copper pipe wrap around the tank, this works to pre heat the oil in the tank before it goes on to the "tricore' heater . For our veggie fuel tank we used a 55 gallon plastic barrel,not because it is superior to other materials but had the great advantage of being ten dollars,as opposed to say, 400 for a nice metal tank .

After the oil leaves the tricore it goes through a 10 micron filter. We used a Golden Rod because you can find replacement filters at any tractor store for very inexpensive. The bus leady has 2 other filters, but since we are usingwaste vegetable oil it is neccesary to filter as many times as possible. You never know what nastyies lurk in used veggie oil.

Our system for retreiving the veggie oil from returaunts is as follows; filter the oil as we pump it into a container (curently using a hand pump), then filter it a second time as we pump it into the bus from the container. This way the oil gets filtered 5 whole times before it reaches the engine. That aught to stop the yucks from entering the sanctity of the engine.

We decided to go minimalistick on the change over process. This meens that after the veggie oil goes through the filter it goes to a fuel pump and then to a ball valve which you have to manualy pull to allow the veggie oil to flow. There is a shut off valve before the traditional diesel goes into the engine also. When we want to change over to veggie oil we start it on diesel , wait till it gets hot enough, open the hood , open the veggie valve, close the diesel valve, open the veggie return line valve and close the diesel return valve. We went with the all manual system because we felt that the less coplicated the system, the less to go wrong down the line. Another big motivation was saving money.

Return line? What say you of return lines?

Well, after the fuel goes through the engine, it does not all get burnt up. The fuel that doesn't get burnt goes through a return line and back to the tank. Many of the pre made conversion kits opt to create a loop and instead of feeding it back to the tank, make it go back through the engine immediately.The Idea is that the oil is already hot so rather than letting it cool off as it goes back to the tank you just put it back into the engine. Greg Makes a good point as why another way might work even better.

The idea is this; If you keep recycling the fuel around and round, you bypass the fuel pump and therefore loose preassure resulting in a larger likelyhood of the engine quiting. What we did is this; we ran the return line along side the tricore and the coolent return line. All these pipes are bound together with duck tape and inulated with spray foam along with the tank. We actually haven't got around to insulating the pipes yet ,but because of the tempraure this time of year ,Idon't know if that's to crucial at this moment.

Another diffrence betwixt our conversion and others I have heard of is the fact that we are using copper and steel pipes. Most other kits use plastic and rubber hoses. The use of rubber hoses makes it much easier to put together,but has two draw backs.

First, the hoses will disinigrate over time. I guess, being that it's so easy to replace, it's not to big of a problem. Then again, when the hose carrying radiator fluid deteriates inside the tricore heating system, it can contaminate the veggie oil,which could be catastrophic.The second is that plastic is a poor transferer of heat. With the copper lines, we are heating mutch more efficiantely.

Thast about it.There are a few things we would like to change and add in the near future.Those things are as follows,

1) a new flat,metal fuel tank with fuel gauge and temp read out

2) Move the on /off valve for fuels in next to the drivers seat.This would allow the driver to switch to veggie or diesel withouit having to pull over and lift the hood.

Before I hand things back to back to Miss Pixie,I want to thank Greg Archambault for his help in designing this system. His knowledge of school buses and diesel engines was indespensible and we could not have done it without him.

Thanks Greg !


bdespain said...


Does your bus run at the normal posted speed limit for the freeway (65 miles per hour)? I don't know why but I picture it running very slowly.

Also, how many miles does the veggie engine run on a gallon of veggie oil? Is it the same miles per hour as a pure diesel engine?

I hope your having a fun time on your journey with the two of you, your three birds, dog and the baby to be.

Good luck with your new engine and have a happy and healthy good time.


nasus60 said...

I have searched the forum threads of etsy for two days to find you. Someone got tired of the post aparantly and I found you. I think what you are doing is awesome. A friend is interested in the particulars of conversion , so was trying to find this.
I wish for you, blue skies,safe travel, and that all the resteraunts you come to are in need of an oil change.

Anonymous said...

In it something is. Now all is clear, many thanks for the information.