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Old 11-05-2010, 02:00 PM
W124 E300D W124 E300D is offline
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Join Date: Aug 2010
Location: UK
Posts: 331
Originally Posted by Marvelicious View Post
The more reading I do, the more I come to a couple conclusions.

1 You should be fairly tech savvy to even attempt to use waste oil as fuel

2 If you are savvy enough to build a good WVO conversion, you're savvy enough to build and operate a small biodiesel converter.

I feel like the filtering, settling effort necessary to ensure the safety of WVO negates any convenience advantage. You still have to "process" it, its just a simpler process. OTOH biodiesel, if properly manufactured and tested should work as well as dino diesel.

For the record, this is based only on what I've read. I've got no personal experience either way, but I've been doing a lot of reading because I have WVO readily available to me. I wouldn't mind putting it to use - but not to the detriment of a car that I really like.


Ideally you want an engine that runs at less than 2,500 RPM, because you start running up against the physical limit of the flame front speed in the combustion chamber with WVO/VO/SVO, this is like det cord, the speed the flame front burns at has little to do with other properties it has, and nothing to do with the ignition method, #2 diesel burns faster so will tolerate higher RPM, you want to go higher than that you work your way up to gasoline, etc etc.

Ideally you want a minimum cylinder volume of 1 litre, the average saloon car, or MB, 500cc is just too small, plot a graph of square (bore = stroke) engines of different cylinder capacity, it is not linear, a 2 x 2 x 2 box has a volume of 8, and an area of 24, so area / volume = 3

a 4 x 4 x 4 box has a volume of 64, and an area of 96, area / volume = 1.5

With the bigger cylinder more of your fuel air mixture is in contact with more F/A mixture, and less cylinder wall, which absorbs free electrons and slows down the flame front and causes incomplete combustion in the eddy layers there.

Ideally you want a direct injection, ideally centre of the bore right down onto the piston crown, ideally you want a flat top piston too, not a swirl chamber one, too prone to producing chips of carbon.

Ideally you want a decent in-line pump, THE ONE THING THE MB HAS, but most 70's and 80's light trucks and buses had in-line pumps too.


Even so, WVO still kills Bosch pumps, I've seen many, many, many Bosch pumps taken of mercs that had over 500k miles, and the pumps were all basically as good as new, these pumps, when fed with clean lube oil and clean filtered #2 diesel, will go a million miles no problem.


As others have said, burning WVO in a home heating furnace is win-win-win, there is no downside, it is all profit.

You can also burn WVO in an old stationary engine powering a gen head to give yourself almost free electric, something like the Lister CS series with separate Bryce injection pump, it is indirect injection (and variable compression) but at a single 1,400 cc cylinder and 650 or 800 rpm max, they will burn anything, so again, it is win-win-win.

I know of people burning WVO very well and very successfully in boats, (essentially stationary engines) because they get tax breaks and "green" subsidies that make it worthwhile.

I know one guy who went the whole hog and built a pukka WVO > Bio-diesel plant, small commercial scale, that produced fuel good enough for vehicles and the makers and the state, he gave it up because it was costing so much per litre of product that he couldn't compete, given the public view of B100 as some sort of inferior product that should be 50% of dino diesel prices tops.

There are so many good things to do with WVO/VO/SVO, but unfortunately running it in relatively small, relatively light weight, relatively high revving automobile engines just ain't one of em.

That's physics, not big oil, not the state, not anything else... just physics.
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