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  #1  
Old 08-06-2005, 09:03 AM
roverhybrids roverhybrids is offline
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Default tuning a diesel engine for SVO

How can a diesel engine be tuned for better performance with SVO/ biodiesel?

Adjust the timing?
Adjust the duration?
Adjust the pressure?
Rework the injectors?
???????????????????

Mostly I'm refering to newer vehicles like VW TDI's and the big 3 pickups. Most of these things can be adjusted with aftermarket "chips" or "boxes"
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  #2  
Old 08-06-2005, 11:51 AM
craigreece craigreece is offline
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Default Tuning a diesel engine for SVO

Here’s what I know about the subject. Retarding the timing decreases NOx, but may also decrease performance. I don’t think you can adjust duration - pump timing only effects fuel delivery - when the fuel is delivered, combustion begins.

Elsbett in Germany includes modified injectors with higher opening pressures with their single tank kits - the higher pressures = finer atomization, and thus more complete combustion. They also change the pintles and nozzles on those injectors - Mercedes and pre-Tdi VW’s - that permit this. And this guy in Colorado sells modified Mercedes injectors:
http://injectors.150m.com/svo.html

Some VW Tdi owners have installed “bigger injectors” that deliver more fuel, and they usually chip the car at the same time, and some VW Tdi owners running biodiesel use them - the idea is that thicker biodiesel will flow more easily through larger orifices. And lots of websites sell larger injectors for the Cummins.

High Compression II, who posts on the InfoPop SVO Forum: http://biodiesel.infopop.cc/6/ubb.x?...51&f=159605551 and who has an excellent UK website: http://www.doctordiesel.co.uk/
has played around with increased opening pressures and is now against it. Here’s what he says about it (and he talks about timing a bit too


"Increasing the opening pressures as done by many pioneers, has worked for them, but has caused other undesirable issues when tried on a variety of my own vehicles.* I can find no basis where the increase of opening pressures will give a "finer spray"--The atomisation is dictated by the design of the nozzle to the greatest extent, and not an opening pressure increase of 10-20%, as is generally advised!

Increasing the opening pressures will effect the RATE of delivery, maybe give a quieter engine generally, however this will retard the effective point of injection and affect the torque delivered by the engine at low speeds, affecting drivability, more noticeable with smaller engines.*This can cause in some cases, smoke in the exhaust due to the now effectively retarded timing, particularly with the DI engine, which are more sensitive to timing inaccuracies.

Advancing the timing may remove the smoke from the exhaust, but the different torque curve from standard will remain.

Experiments in the reduction in opening pressure have given good results, on a variety of engines in starting from cold, drivability and emissions. probably due to Vegetable oils different viscosity properties.

Advancing the timing whether you leave the opening pressures as standard or not, helps with starting from cold, carbon and gum build-up at the nozzle face, and general smoothness of the engine as a whole. Injection Timing should be advanced around 3-4 degrees crank, but no more--doing so will cause possible overheating of the engine or nozzle and an increase in diesel knock.

The advancement in timing counteracts the apparent difference in delivery speed of the more viscous vegetable oils. During fuel delivery, fuel does not flow in the normal way, At the high injection pressure pulses, the fuel is slightly compressible, and the fuel lines are slightly expandable. The fuel passes through the lines in the form of a pressure wave, expanding the high pressure line rather like the cartoon interpretation of water flowing through a fire hose. The speed of this pressure wave is dependant on the fuel*itself, and the effective speed of sound in that fuel. Vegetable oils have different properties, most notably its viscosity, which appear to be slower than standard diesel fuel*in this respect."

Craig
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  #3  
Old 08-06-2005, 12:31 PM
Fordnut74 Fordnut74 is offline
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Default

Craig, good stuff there, thanks for sharing. When I was reading some articles that I believe are posted here on the Frybrid, They mention that WVO generally not as compressable as diesel is. And under the very high injection pressure seen by today's diesels, (23,000 psi for 7.3 psd's), that effectively increases the static timing by a few degrees due the quicker reaction from the oil. In theory, The WVO should result in less power because it has a lower kinectic energy than #2 dinofuel does, however the increase in timing at least for my truck seems to have offset that bit, and just results in about 15% lower fuel economy. But who cares? it is nearly free. I have documented running a 15.2 1/4mile on #2, and a 15.4 on oil. 2 tenths obviously indicates a slight loss in power, but that is something that would be hardly noticeable in seat o the pants.

TO answer the original question, My truck has responded very well so far to the performance mods I have done to it, which mostly inlcude a programmer, some turbo stuff and exhaust. When I return, I plan to go down this road further with custom chips, and play with timing, injectors, injection pressure, and etc. I would like to make comparisons between the diesel and WVO the entire way to document any siginificant differances.
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  #4  
Old 08-06-2005, 01:45 PM
roverhybrids roverhybrids is offline
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Quote:
Originally Posted by Fordnut74
TO answer the original question, My truck has responded very well so far to the performance mods I have done to it, which mostly inlcude a programmer, some turbo stuff and exhaust. When I return, I plan to go down this road further with custom chips, and play with timing, injectors, injection pressure, and etc. I would like to make comparisons between the diesel and WVO the entire way to document any siginificant differances.
This is where I am headed and your results are/will be just the info I'm searching for. I want to tune my truck for better performance on WVO and 400+hp to the ground. This amount of power is attainable with an intake, exhaust and a box on my truck using diesel fuel.

I have tried a reputable performance box on my truck, the seat of the pants feel was great; but the idle became ruff. The main problem was that it caused a check engine light. Through a few codes. One was rail pressure too high. One was RP too low. One was lost communication with something(I forgot) Anyrate that box has been sent in to get checked out and I'm not sure yet if it was a problem with the box or the combination of the box and SVO.
So I'm trying to educate myself on which upgrades will also benefit performance on SVO

So so far we're saying:

Advance timing.
leave stock pressure, though there may be an increase from using SVO
duration?
injectors? possibly larger?
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  #5  
Old 08-06-2005, 02:03 PM
craigreece craigreece is offline
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Default Tuning a diesel engine for SVO

I think FordNut is saying that SVO advances the timing due to it's viscosity - not that he'd advanced the timing. Alexander Noack, the senior engineer from Elsbett who's their conversion guy, told me that with SVO, "start of combustion is delayed" which sounds to me like SVO *retards* the timing - which makes sense - thicker SVO takes longer to fill the combustion chamber = retarded timing. So, advancing the timing might result in power gains aka restore power lost to retarded timing. Any tweaking of timing should be accompanied by a close recording of EGT's, since pump timing can result in higher EGT's (which can be reduced by a larger intercooler, or water injection, or alcohol injection.)

And propane injection can increase power. The propane injection system I'd trust above the others is MSD's - since their ignition stuff is so bomber. But you need a fairly large tank, which is a liability for our application, since we're already adding a tank.

Craig
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