ORIGINAL: Green_VerMonster

Some SVO notes.

First of all, I do SVO conversions, and I stake my reputation on building a system that will not fail or cause problems. I also like to inform others, and have helped folks set up their own system, as I would rather see someone have a sucessful system than get ripped off and have a system that harms their engine, and end up with more SVO HORROR STORIES ::GASP::
Anyhow, there are several important points I would like to make.
First, of all, SVO is not Biodiesel... Biodiesel is veggie oil or other fat (chicken fat is suprisingly sucessful) that has been chemically changed in a process called trans esterification, which is similar to making soap. Biodiesel is the fatty acid methyl (or ethyl) ester of whatever kinda oild you start with, and can run in any diesel with no modifications.
The othere safe way to burn veggie oil, is to go with an svo system. Basically, the diesel engine was designed to burn veggie oil, however, the oil guys found that the crud left over from refining gasoline and kerosene would burn in Rudolph Diesel's engine, so they marketed it as 'diesel fuel' (actually, chemically there is no such thing as diesel fuel, it is a mix of different chemicals that meet certain standards, there is more uniformity in biodiesel thatn petro-diesel). So, the engine was designed to burn veggie oil, HOWEVER, in the hundred years since then, engines have been tweaked to burn diesel better.
Diesel is thinner and runnier than veggie oil, and injection pumps and injectors have been perfected for diesel use. If you run cold veggie oil through the stock injectors you will not get a good spray pattern, and you will get poor combustion. Therefor, you need to either thin the veggie oil with some sort of solvent (diesel, kerosene, or some such) or heat your oil so it will thin. If you do not do this you WILL have problems eventually.
What will happen if you do not thin the veggie oil:
1 Your fuel will not atomize so you will end up with carbon deposits and coning on your injectors.
2 You will get unburnt oil accumulating in your cylinder since it is not burning, this will do several things, it will find it's way through your rings into your lube oil, it will accumulate carbon from the combustion, and it will become varnish on your cylinder walls. Shiny black varnish. Lots of it. Hard, incredibly durable, incredibly resistant to solvents....
3 eventually the temp will drop to below 35 or so degrees and your liquid oil will become shortening. Shortening does not tend to flow very well through fuel systems.
You will probably be fine for several thousand miles running cold unthinned svo, then one day you will start to notice power loss, if you are on the ball you might pull your injectors and notice a carbon build up and be able to either clean the injectors or more likely replace them and have no further probs (for awhile if you keep running cold svo). If you are like me, you will probably limp along for a while.... Hopefully you do something before your engine oil becomes a varnish sludge (not so good for lubricating) or you need to rebuild your engine and hone your block to remove the coking....
Many folks have had luck with blending solvents with oil, they have managed to thin it consistantly, they have managed to keep it from seperating in the tank, they have not had the DMV dip test their tank and find kerosene, they have not added enough gasoline to raise the octane to a point where it will not combust in a compression engine.... I am not a fan of solvent based svo, you can have good luck with it, but I prefer not depend on luck.
I recomend a well designed two tank svo system for most vehicles. You can buy a kit for arond 2500, (heck, I'll even sell ya one) but you can save yourself lots of cash and build your own. Basically, the most dependable systems use a coolant loop to heat a heat exchanger which your oil will run through, and a seperate tank and fuel filter, along with a series of solenoid valves to switch between svo and diesel.
The KEY thing is to control heat. You have to heat your oil to extremely high temps to match diesel's viscosity, however at 140-160 it is close enough to burn cleanly.
Let me say one thing loud and clear:
THE STOCK VP44 IS UNSUITABLE FOR SVO CONVERSION.
THE STOCK VP44 IS UNSUITABLE FOR SVO CONVERSION.
EVERY issue I have personally seen with a dodge svo conversion was with the vp44.
The heat required to bring the fuel up to safe temp is more than the electronics can take... one with the fedex modifications is possibly ok, but overall the vp44 is as unreliable as an svo pump as it is a diesel pump. (I don't like the verypoorfortyfour, in fact have retrofitted a 24v to the 12v pump(it was a pain, I would gladly talk about it if anyone is interested)
So basically, the system works as follows, you start on diesel (or biodiesel) and run the engine til your coolant is up to temp (some poorly designed systems reqire you run on diesel untill the coolant heats your veggie tank, about 30-45 minutes) and you switch over to veggie, you run on veggie, then you switch over to a purge setting shortly before you stop (if you are going to be stopped long enough to let the engine cool) so that you don't end up with veggie in your fuel system, and have problems starting. You can heat your tank electrically as well, so that you can plug in and keep your veggie tank hot if you want, as well as add 12volt heaters to the system to augment heat durning cold weather or lond descents etc.

Another thing to consider is your veggie oil source, it should be liquid at 'room temp' and not rancid, and there should be no water in it. You should filter it, and allow it to settle before pumping it into your tank. If you are pumping straight from the grease trap, vat, or barrel directly into your fuel tank, you risk getting much more water in the system than your filter can handle. Also, if there is residue from degreaser in that water you will have corrosion issues. Basically, you should pump into at least a 55 gal drum, through a filter, (200 thread cound bedsheets work well, and are cheap and reusable) then allow the drum to sit for at least 24hrs, and carefully pump the oil from the top, until you see the schmutz level which will form at the bottom.

You can assemble the parts yourself for a very dependable svo kit for several hundred to 1000 dollars or you can buy essentially the same thing for more than twice that, you are basically paying for someone else to do your leg work, and a manual to install the kit. Many kits do not regulate heat well, some do not even have a temp gauge!
~Ben

::edit fixing some typos, good thing I'm not a secretary::