Quieter engine on SVO is not better

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

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Postby hheynow » Sat May 31, 2008 9:45 pm

Diesel is used in a high-compression engine. Air is compressed until it is heated above the autoignition temperature of diesel. Then the fuel is injected as a high pressure spray. There is no ignition source. As a result, diesel is required to have a high flash point and a low autoignition temperature. The flashpoint of a fuel is the lowest temperature at which it can form an ignitable mix with air. The high flash point in diesel fuel means that it does not burn as easily as gasoline, which is a safety factor. Too low of a flash point is a fire hazard because ignition may continue and lead to explosion.


from HERE


I've never understood why people recommend RUG over #1 or #2. My friend was just given 40 gallons of mixed #2/RUG from a repair shop who had just drained a diesel tank. He has a Mercedes. I think he's nuts to run it diluted or not.
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Postby Welder » Sun Jun 01, 2008 2:20 am

Okay, after DCSs interesting post, I can only anticipate an equally interesting response from Sunwizard. I hope to learn from this exchange.

Maybe I am stepping into this thread at the wrong time, but if anyone has time to respond, here's my question:

IIRC, in my older (1988) 7.3 IDI, there's no digital tuning facility, it's all mech timed. That would likely mean I either time for ULSD or veggie.

Is it better to time my truck for ULSD or veggie?

It would always be wrong for one fuel, but which is it better (less damaging) to be wrong with? I guess the answer depends somewhat on which fuel is burned the most, but perhaps other factors apply too.

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Postby SunWizard » Sun Jun 01, 2008 9:44 am

David wrote:In a petrol engine, it is rare to see compression ratios over 12:1 due to the problem of the petrol self igniting in an untimed manner.
In high compression engines, this is always pre ignition which mean the fuel burns in the compression stroke earlier than it should and causes engine damaging knock.

The knock on a petrol (gasoline) engine is far different than the knock in a diesel. Knocking in a gas engine occurs because the fuel is in the cylinder during the entire piston intake and compression stroke and reaches its AIT before the spark goes off. This is pre-ignition and why RUG is required to have a high AIT, and premium RUG has even higher AIT.

A diesel injects the fuel right at the proper time for the start of combustion. Its not in the cylinder for 2 entire strokes as in a gas engine. The fuel still needs to reach its AIT in order to start ignition. This is called ignition delay, the very short time between injection and ignition, and is a direct function of AIT. If you have Diesel or Kerosene in your blend this will occur sooner than with RUG, and is what we want, a shorter ignition delay.

If you want to use RUG as your blend thinner (because its cheaper or free for some), it makes sense to still use some % of Diesel or Kerosene for the timing benefits discussed in this thread. It would be interesting to experiment with different percentages of D2 or K1 to find the best % to still get the same healthy diesel knock sound as on 100% D2. In my blends in my 300D I find around 20% D2 is about the lowest I go to get the same sound of knock. Below 20% it gets noticeably quieter, and I can feel the lack of power. And a lack of power becomes a big problem in an already low powered car like my Mercedes 300D (non-turbo).
Last edited by SunWizard on Mon Oct 11, 2010 7:12 pm, edited 2 times in total.
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Postby coachgeo » Sun Jun 01, 2008 10:27 am

it seems everyone is discussing this as if the RUG changes the character enough of the other fuel to create ONE IGNITION POINT that happens to not fit with the timing of the engine.

BUTTT.... from the years back stuff I read of Kugel who put lot of study into this..... I believe he came up with that there is TWO IGNITION POINTS when blending with RUG and this second one (my memory says its RUG) helped get a more complete combustion of the other fuel (WVO or diesel)

Dimenishing returns exist though and too much RUG and you loose that second ignition point. Maybe too much RUG is when the blend creates one ignition point. One that is off synch with typical diesel ignition timing.
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Postby coachgeo » Sun Jun 01, 2008 10:59 am

This thread has become more about RUG and not "silent is better?" which was the orginal topic. Yet their is some relationship. I know somone was smart enough to start an RUG thread to try to take this to its own spot so this ones orginal subject could stand alone.

How do you folk feel if I use the Moderator tools to peel from this thread the post about RUG, and place them into the RUG thread so the two topics (silent is better, & RUG good, bad, and ignition timing adjustments) can carry on without competing with each other?
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Postby SunWizard » Sun Jun 01, 2008 11:34 am

coachgeo wrote:This thread has become more about RUG and not "silent is better?" which was the orginal topic. Yet their is some relationship. I know somone was smart enough to start an RUG thread to try to take this to its own spot so this ones orginal subject could stand alone.

How do you folk feel if I use the Moderator tools to peel from this thread the post about RUG, and place them into the RUG thread so the two topics (silent is better, & RUG good, bad, and ignition timing adjustments) can carry on without competing with each other?


Agreed, I was thinking of doing that.
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Postby hheynow » Sun Jun 01, 2008 12:09 pm

Getting people off of RUG and on to #1 or #2 for timing advance should be the focus since those of us with computers can't adjust our timing as easily as those with mechanical controls can. IMO they are all tied together and the thread has not drifted. Learning about why we run quieter on WVO and solving the needed timing advancement by fuel blending is directly on course with the jist of this thread.

$.02

George the topic is not "silent is better"
Last edited by hheynow on Sun Jun 01, 2008 12:20 pm, edited 1 time in total.
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Postby SunWizard » Sun Jun 01, 2008 12:15 pm

hheynow wrote: those of us with computers can't adjust our timing as easily as those with mechanical controls can.

Many of the mechanical pumps are not easy to adjust the timing either.
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Postby John Galt » Sun Jun 01, 2008 12:28 pm

Less engine noise is not always worse as long as the fuel mix charge is completely burned, i.e. low HC emissions, low exhaust opacity.
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Postby SunWizard » Sun Jun 01, 2008 12:55 pm

John Galt wrote:Less engine noise is not always worse as long as the fuel mix charge is completely burned, i.e. low HC emissions, low exhaust opacity.

Quieter is worse if your power is worse, you would need to do a dyno test on both fuels and compare. On my 300D the difference is large enough I can tell even without a dyno, from the hill climbing ability.
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Postby John Galt » Sun Jun 01, 2008 3:07 pm

Quieter is worse if your power is worse

for sure...

The perceived disagreement comes from approaching fuel mixes from different directions.

My diesel fuel does not come from terrorist oil; it's 100% domestic.
I'm not trying to "stick it to the man", the dollars I spend on petro fuel pay Canadian workers distributing fuel and operating refineries, drill rigs, exploration crews, etc. and puts food on the table and a roof over their family.

Many VO users want to use as high percent of VO as they can without immediate engine damage. They approach blending as adding solvents to 100% VO to avoid cold fuel issues and 'dirty' start-ups in unheated systems.

I'm exploring ways to make diesel fuel burn better, with less particulate exhaust, less pollution, less objectionable odor for pedestrians, and at the same time use a limited VO resource which would otherwise be discarded as waste. I'm using VO as an additive to diesel fuel in amounts which will not require modifications to the vehicle fuel system, or cause long term damage.

The key to engine longevity is clean combustion, especially at cold engine starts. VO/ULSD blends including naptha or RUG, and kerosene, combined with plug-in preheating can significantly reduce cold start deposits. The blend will also reduce unburned fuel during normal operation especially at open throttle conditions on hills or pulling loads.

Without access to a dyno there are hills which offer constant loads for evaluating differences in power.

There is no power loss with the 60%ULSD2, 20%VOcanola, 10%JetB, 10% D1-kero mix I'm currently testing. The JetB is basically a 50:50 mix of kero and gasoline [naphtha], so the equivalent 'RUG' component is ~5%. Ambient temperatures at this time of year range from 5°C to 25°C. Preheating brings the injector lines and fuel filter to ~40°C and the engine block to ~20°C. Preheat time depends on ambient temperature. When the engine is stopped heat soaking will raise the injector line temperature to 70°C and the engine stays warm for hours unless it's extremely cold. Restarts on a warmed engine are clean.

So far this fuel mix meets my expectations. The engine runs quieter with no perceived loss of power or MPG, and the exhaust is clean, and not unpleasant to smell. The VO and jetB are 'free' so the economic savings balance the time spent on what's mostly another research hobby.

If anything there appears to be more low RPM power when moving at varying traffic speeds in 4th gear. It will slow to 30kph and accelerate smoothly from that speed to 50kph with just a small amount of throttle, and no engine lugging. The engine isn't operating behind the power curve and I'm down shifting less and using less throttle in traffic, which likely explains the minor increase in MPG.
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Postby SunWizard » Sun Jun 01, 2008 9:22 pm

Here is a relevant quote from Crossbones who is an expert on the timing subject but has quit posting at infopop:
"Do not be lured into thinking that when using VO as fuel and diesel knock is substantially less that this is better for your engine..."
Update-challange- Glow plugs as sensors (crossbones)
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Postby David » Mon Jun 02, 2008 1:49 am

hheynow wrote:Getting people off of RUG and on to #1 or #2 for timing advance should be the focus since those of us with computers can't adjust our timing as easily as those with mechanical controls can. IMO they are all tied together and the thread has not drifted. Learning about why we run quieter on WVO and solving the needed timing advancement by fuel blending is directly on course with the jist of this thread.


I was of the impression that computer controlled engines were easy to change timing on by just adding a chip and plugging into a laptop.
My merc has 4 bolts holding the pump. The Mercedes engineers must have put considerable time and effort into working out how to place on bolt in a position it can't even be seen, let alone accessed with any thing other than a special ( read expensive) OEM tool and then of course there is the crowbar and and other handy items like 4x3" lumps of hardwood.

There is no power loss with the 60%ULSD2, 20%VOcanola, 10%JetB, 10% D1-kero mix I'm currently testing. The JetB is basically a 50:50 mix of kero and gasoline [naphtha], so the equivalent 'RUG' component is ~5%.


Being 4 part, that is one of the more comprehensive mixes I have read of.
Interesting to see that you too feel the 5% RUG is a help in this blend.

I believe he came up with that there is TWO IGNITION POINTS when blending with RUG and this second one (my memory says its RUG) helped get a more complete combustion of the other fuel (WVO or diesel)


I am of the belief this is unlikely. When there are 2 flamefronts in a cylinder, they tend to collide and produce distinct knocking or nailing. I also think it unlikely that 2 fuels with very different properties would ignite at the same time.
If they didn't light off at the same moment, once one lot of fuel lit, it would would propagate very quickly and light off the other fuel. I can't see how the fuels could burn one after the other without setting the other off at the initial combustion nor can I see any mechanisms for the 2 different fuels to ignite independently at the same time.
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Postby hheynow » Mon Jun 02, 2008 11:27 am

David wrote:I was of the impression that computer controlled engines were easy to change timing on by just adding a chip and plugging into a laptop.


I really need to call the fellow who burned my chip and find out if he can re-burn it to give me an SVO setting.
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Postby Welder » Mon Jun 02, 2008 3:31 pm

SunWizard wrote:Here is a relevant quote from Crossbones who is an expert on the timing subject but has quit posting at infopop:
"Do not be lured into thinking that when using VO as fuel and diesel knock is substantially less that this is better for your engine..."
Update-challange- Glow plugs as sensors (crossbones)


How interesting that you quoted Crossbones, Sun. He popped into my mind when I first started reading this thread. His input here would have been nice.

So he stopped posting on infopop? That's really too bad. I wonder why? I hope he's okay.

Maybe someone could shoot him a PM on infopop so if he ever logs on over there, he could be invited over here. He wrote some really interesting stuff.

Sorry for going somewhat OT, but it was ironic that we both though about the same guy in regards to this thread.
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