propane and biodiesel

For discussing the modifications needed for diesel vehicles to run with 2 tank veggie oil conversions.

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propane and biodiesel

Postby cantrellc123 » Sun Jul 20, 2008 8:59 pm

Hey All. I'm new to this forum, 1st post. I read the thread"Quiet engine on VO is not good". This got Me to thinking about My truck,a late 99 ford that I run B100 and a small amount of propane-1gallon per 100 mile avg.Once I began using bio the quietness of the engine was very noticable so according to said thread the timing should be retarded a bit with bio? Well My understanding of propane and diesel engines is that the propane will advance the timing some amount. I have noticed a slight decrease in milage with bio vs. petrol diesel but am still very happy overall. My question is Would burning propane with VO advance the timing back closer to normal?

FWIW I have used propane for nearly 200k on this truck 328k total. Once I started using propane the engine got quieter. I'm fairly certain that propane advances timing some and improved performance which would be an opposite reaction to the info of said thread concerning VO and a quieter engine.

I hope that My posting here doesn't upset anyone since I don't burn VO, I'm just trying to learn if the avenue presents itsself?
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Postby 240Volvo » Sun Jul 20, 2008 9:48 pm

Welcome to the forum! I can't answer you question, but perhaps I can clear up some of the confusion.

The thread you refer to is about the difference in the way that VO burns compared to petro-diesel. As VO burns more slowly than petro, advancing the timing causes the VO to be injected earlier in the combustion cycle, giving it the additional time (in comparison to petro) that it needs to combust more fully (and return the "diesel ping" to the sound of the engine). That thread refers to the observation made by many over the years that VO makes their engine run quieter than petro. By explaining the mechanism that accounts for that difference, and how that does not represent an improvement in engine function, it is hoped that more people will adjust the timing to improve engine performance and longevity. I don't know how much difference the trasesterification that bio undergoes would effect this characteristic.

Somewhere I remember a post (probably from Sunwizard) that gave a chart of different diesel fuel oils and their combustion characteristics. It included biodiesel, which might help answer your question, but did not include propane, which would not help. As I recall it, propane helps to oil to combust more fully, and would give you more power (and fuel economy, as measured by your bio use- but don't forget to consider the additional fuel that the propane represents). Different oil stocks exhibit different amounts of BTUs, generally the figure that most commonly available seed oils would give amounts to 10-12% less power and mileage than petro. This also effects the bio made from different oil stocks. Unless someone here has more specific knowledge (and there are not a lot of vehicles that come equipped like your truck-pretty cool), you might try finding a place that does race tuning in your area. David has a water/methanol injector on his MB, he might have some thoughts to illuminate us.

If you do experiment with tuning, please post your results.
1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
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Postby David » Mon Jul 21, 2008 8:22 pm

It is my belief that any aromatic fuel will advance the timing in a diesel simply because aromatic fuels are normally run in engines with much lower compression and cylinder temps when they are admitted to the engine and in a diesel, will light off before the non armatic components. ( diesel SVO, bio)

Due to the heat caused by compression in a diesel, any fuel that is admitted to the engine and compressed rather than being injected injected close to the end of the compression cycle, is going to light off faster than the diesel. I find it likely that this will in turn cause the diesel to light off the moment it is injected to a probably already burning cylinder and therefore the timing overall would be advanced.

I don't believe any of these things make the wvo combust more fully, I believe what happens is that by lighting off earlier, the energy they hold in the peak cylinder pressure has more time to act on the piston and transfer that energy into useful work before the cylinder pressure is lost by the exhaust valve opening, in effect, prematurely.

When using water injection with 50% methanol, I believe the same things take place as with LPG injection and the performance increase would seem to be greater than the amount of extra fueling and power the Meth alone would provide.
Due to the advancing of the timing I believe aromatic fuels create, I am also going to try adding 5% RUG to the WVO in the oil tank of my 2 tank conversion to see if that brings about any benefit in power or reduces the often substantial smoking I see when the car is idling at the lights.

I can procure a source of drained aviation fuel and despite the view that the higher octane is detrimental in a diesel engine, I do not see this as being a problem when the fuel is used in such a small proportion. I'll do my tests one at a time and see how my theroys pan out!
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Postby 240Volvo » Mon Jul 21, 2008 9:05 pm

Thanks for posting, David, I knew you would have something interesting to add.

I think that John Galt poted some info on different fuels, including jet fuel. As I recall, it is mostly kerosine, with several parts various aromatics, RUG, naptha, and some of the -enes in smaller proportions. Different engines, though....

Would be nice to get my Volvo "flying low." 87HP doesn't get a 3500lbs car moving real quick! I am going to install a meth-water injection system this summer, and I'll post results.
1984 Volvo 240 diesel with a single tank Elsbett conversion: electric fuel filter heater, FPHE, glow plugs, and injectors. Also injector line heaters and block heater, running 20%kero/80%WVO winter blend.
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Postby VegMeister » Thu Jul 24, 2008 10:45 am

David,

It might be a Canadian thing but up here we call them "petroleum" fuels. Aromatics are a subset of petroleum fuels.

Other that that I agree with your post, adding petroleum products such as kerosene will indeed thin out the fuel. I don't know anything other than that FOR SURE. I could repeat information that I've heard on other threads... but I'm not going to bother. hey guys!! I got my diesel diagnostic tools in from the snapon guy and ebay yesterday! So I'm off to do some real learning on my 6.5 :)
centralvalleybiodiesel CF
1993 GMC Sierra K2500 6.5L + homebuilt veg kit, OEM glowplug failure (update: rebuilt with a 6.2 block, working fine)
1988 Ford 6.9L OEM dual tank, 90+% veg oil blend.
1989 Ford 7.3L, 80+% veg oil blend.
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Postby David » Sat Jul 26, 2008 9:57 am

Vegmiester,
I am not sure of the exact definition of an aromatic but my understanding is that is is a liquid that gives off sufficient vapors at room temperature to be lit with a match.

Things like petrol, methanol, ethanol, acetone, LPG etc would fall into this catergory where as I class what I believe to be oils, Diesel, kero , turps veg oil etc to be non aromatic because you can't pout a small amount into a tin and light it without heating it up first. I may be out on these definitions but that is what I class them as anyway. :)
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I don't give a damn about what might or could happen until a significant group of people can tell me it HAS happened to them.
Until then, it's just more endless gloom and doom Veg folk law.
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Postby VegMeister » Sun Jul 27, 2008 7:00 pm

David, you make perfect sense, and now that I think about it I agree on your definition of aromatics. Thanks! Now I'm doing a bunch of chemistry reading :)
centralvalleybiodiesel CF
1993 GMC Sierra K2500 6.5L + homebuilt veg kit, OEM glowplug failure (update: rebuilt with a 6.2 block, working fine)
1988 Ford 6.9L OEM dual tank, 90+% veg oil blend.
1989 Ford 7.3L, 80+% veg oil blend.
VegMeister
 
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