This is from another forum - Just a little FYI

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This is taken from the new pages at Greasel.com

I've heard that that there are problems associated with running SVO
in direct injection engines, is this true?
The short answer is no, for the long answer, read on:

TDI verses IDI

There've been a lot of questions, and misinformation regarding the
suitability of the direct injection engine to burn straight vegetable
oil. Here is some information that will help you make up your mind
for yourself.

The indirect injection diesel uses a pre-combustion chamber that
is connected to the main space above the piston by a narrow passage
way. When the fuel is injected into the chamber, there is not enough
oxygen for complete combustion, but enough combustion happens to
raise the pressure of the chamber to cause the fuel air mixture to
rush out through the narrow passage into the main area above the
piston. This rushing out through the passage completes the mixing and
atomizing of the fuel /air mixture, where it completes its burn.

This type of engine is tried and true when it comes to burning
vegetable oil.

The Direct injection Diesel takes a different approach to mixing
the fuel with the air. The chamber is designed to energize the air.
The two things used are swirl, and squish. The angle of the intake
seats causes the air to swirl as it enters the chamber. The edges of
the piston crown parallel to the chamber roof, when the piston gets
close to TDC the air gets squished between these two faces to the
center of the chamber. The fuel is injected directly into the main
chamber above the piston, into this turbulent air, and is mixed and
burned.

Direct injection Engines with high pressure unit injectors
(20,000- plus PSI) make the fuel an active element in the mixing
process. A Detroit diesel is a good example.

The most common fear sited, is that running a DI diesel on veggie
oil will cause injector coking. Injector coking is the build up of
carbon, due to incompletely burned fuel. This causes the spray
pattern of the injectors to deteriorate, causing more unburned fuel,
and the problem gets worse in a real hurry.

If there was a problem with injector coking it is more than
likely that the problem would manifest itself within the first 1,000
miles or so, and get progressively worse. The symptoms of coked
injectors are, Hard starting, excessive smoke, drastic drop in fuel
economy, and substantial loss of power. Of all of the engines we have
converted, Indirect injection and Direct injection, there has never
been a problem with injector coking. Furthermore, I have never
been presented with any evidence that would lead me to believe that
it is a problem. When I hear someone say that a DI run on SVO will
have problems, I ask them where they got there information, and if
there is any proof. To date, nobody has ever produced an engine that
had these problems. The closest I get to fact is, that some
university ran a generator on unheated SVO for 25 hours and had
injector coking.

On the other hand, we have converted more than a few DI engines
that have over 10,000 veggie miles on them with no problems. That's
just our customers. There are TDI VW's that are in Germany that have
close to 60,000 miles on them, and several in the US that I'm aware
of that has over 60,000. veggie miles on it.

The other myth/urban legend is that if there is a computer
involved with the injection system that you can't run SVO/WVO. I have
done 7 different makes of engine with computer controlled injection
systems, and not one of them freaked out when we flipped the switch,
and continue to run great.

As for the different types of injection systems, Rotary, inline,
common rail, unit injectors, and CAV. We have done them all, and all
work great.

The CAV does not have that many veggie miles yet, and the jury is
still out. Others have reported problems with them, but this is the
first one with our kit on it, so we will be watching it.

The great thing about running veggie oil is that it lubricates
allot better than low-sulfur diesel. It will actually extend the life
of your injection system.

I have a customer with an old car that was idling funny on
diesel, and idling normal on veggie oil. When he ran the whole
scenario by the guys at injection pump rebuild shop, they said that
the seals were probably worn out with age, and that the superior
lubricating qualities of veggie oil was what was keeping it alive.

__________________
98 K2500 Suburban 6.5 Luxo Barge

"We cannot change the wind - But we can adjust our sails"