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Rudeboy -> Re: More bio fuel stuff (6/4/2003 3:00:43 PM)
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[QUOTE]Originally posted by hobbsy
I ran my Fox .74 conversion on bio fuel to see if the fuel would even burn. It burns and burns very well. I used RedMax concentrate, 65% ether, 30% castor and 5% ignition enhancer. I mixed a quart of this with two quarts of soybean oil. The ingredient percentages should then be about 21% ether, 10% castor and 1.5% ignition enhancer. Some of you percentage experts feel free to correct me if this is wrong. I had the engine set up for Davis fuel and instantly realized that the compression was too high. Even with the compression screw backed out all the way the compression was too high above half throttle. This was not a problem below 7,000 rpm. I ran out a 16 OZ tank in the 5,500 to 6,000 rpm range just to let it run. Since than I have made two shims from one of those throw away aluminum cake pans and will try it again. I also want to try it in my PAW .60. I'll let you know how it goes. [/QUOTE]
Well you almost had the percentages right Dave...:D:D:D
They are actually:
21.67% ether
10% castor oil
1.67% ignition enhancer
66.67% soybean oil
But seriously now... How does the engine smoke on the mix stated above?
I think the reason for the excessive compression is because you're burning pure oil... well not pure, but you know what I mean.
What happens is that at lower rpm levels only very little of all that oil evaporates and subsequently burns. But as the rpm rises, the temperature and pressure in the cilinder rise also, so more of the oils evaporate, which rises the temp and pressure even more,... etc. etc. .... chain reaction, you get the picture.
My guess is that you have to set the needle fairly rich in order to get enough ether up there to keep combustion going with all these heavy oils in the fuel. In fact, I think your engine is running almost completely on the ether and ignition enhancer...The result of this is that at higher rpms too much oil starts to evaporate which in turn causes over-compression...
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