Author Topic: High performance alternative waste oil blend diesel fuel  (Read 9559 times)

Excalibur

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Re: High performance alternative waste oil blend diesel fuel
« Reply #15 on: August 13, 2012, 08:12:19 PM »
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Are y'all using E10 from the pump or ethanol free gasoline? What octane? I'm using 87 E10 as it's my understanding we WANT detonation.
I use 97 octane with no ethanol content. I understand that the fuel is required to detonate at the point of injection.
Confusion with the term commonly relates to detonation of a gasoline motor. With those, the fuel/air mixture is compressed and a spark added at the desired firing point. However a diesel only compresses air and the fuel is added at the point of firing.
A diesel can't fire before the fuel gets there.

Jhanananda

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Re: High performance alternative waste oil blend diesel fuel
« Reply #16 on: August 14, 2012, 05:56:25 AM »
Interestingly I'm not seeing a performance increase running 20% Gasoline/80% waste oil. It runs better and smokes less than 100% waste oil, but not as well as D2.
Diesel engine designs vary, so we can expect different percentages of solvent to waste oil will work for different engines.  My engine runs better on 80% WVO to 20% gasoline than on D2; however, my engine runs like it has a turbo charger in it if I increase the gasoline content of my WVO blends to 30%.  So, you might try increasing the gasoline content in your blend in 5% increments until you find a sweet spot that works for your engine.  When you find it, do let us know.
Are y'all using E10 from the pump or ethanol free gasoline? What octane? I'm using 87 E10 as it's my understanding we WANT detonation.
I am using normal pump regular unleaded gasoline available at the pump here in Arizona, which I understand is E10, to thin my waste oil blends.  I have found that E10 will destroy most seals at 100%.  It seems to run indefinitely at 20-30% in my engine. 

I plan to conduct an experiment shortly to determine just how much E10 can be added to a waste oil blend before seal failure modes appear.  The experiment will simply be to make up a series of blends in jars, then drop in 2 seal samples that were precisely measured with a micrometer.  The seals I plan to soak in E10 are BunaN and silicon, because I know my injector pump has both seal types in it.  A 24 hour soak should be sufficient to determine seal swelling, or failure.
I use 97 octane with no ethanol content. I understand that the fuel is required to detonate at the point of injection.
Confusion with the term commonly relates to detonation of a gasoline motor. With those, the fuel/air mixture is compressed and a spark added at the desired firing point. However a diesel only compresses air and the fuel is added at the point of firing.
A diesel can't fire before the fuel gets there.
Yes, there is quite a bit of confusion over the terms that are related to detonation in internal combustion engines.  Those terms are octane verses cetane.  Mostly those terms are used by marketing people for the petroleum industry to sell fuel, and the fuel additive industry to sell fuel additives.  Physicists and chemists generally do not use those terms.

As you know combustion in a spark ignited engine is different than combustion in a diesel engine.  As we have shown gasoline can be blended with waste oils to make diesel fuel, and there are reports all over the WWW that doing so works great on a wide variety of diesel engines.

Gasoline is not "required" to ignite at anytime in any engine, but does when the conditions for ignition are met.  If the conditions for ignition are properly met, then we have nearly complete combustion.  There are a range of parameters that will produce the conditions for ignition.  Those parameters for combustion are different in diesel engines verses gasoline engines.  The parameters for combustion are also different from one fuel blend to the next.

Waste oil blended with diesel fuel retards ignition, which is observed by increased emissions and loss of power. Adding gasoline to a waste oil blend advances ignition.  So, understanding that waste oil in a diesel fuel blend retards ignition, and gasoline in a diesel fuel blend advances ignition means we can control ignition in a diesel engine by simply adjusting the fuel blend until it meets the parameters for combustion that are similar to D2.  Most blenders find waste oil blends containing gasoline at 20% meets those specifications.  And, some blenders also find increasing the gasoline content up to about 50% will increase the performance of a waste oil blend.
« Last Edit: August 14, 2012, 06:04:02 AM by Jhanananda »
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

sathackr

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Re: High performance alternative waste oil blend diesel fuel
« Reply #17 on: August 17, 2012, 07:26:57 PM »
So, you might try increasing the gasoline content in your blend in 5% increments until you find a sweet spot that works for your engine.  When you find it, do let us know.

I'm at 30% now, which is running better than 20%. I haven't tried greater than 30% yet but intend to.

I am using normal pump regular unleaded gasoline available at the pump here in Arizona, which I understand is E10, to thin my waste oil blends.  I have found that E10 will destroy most seals at 100%.  It seems to run indefinitely at 20-30% in my engine. 

Non-ethanol gasoline is readily available here though it's typically priced higher than D2. I'm not sure what they use as an octane increaser or if it's alcohol based.


...over the terms that are related to detonation in internal combustion engines.  Those terms are octane verses cetane.
I understand the "octane" rating to be related to the temperature at which the fuel will auto-ignite. I understand the "cetane" rating to be related to the speed at which the fuel burns. In an engine where we rely on the heat from compression to ignite, we want the autoignition temperature to be low (I think d2 is around 450f vs rug at about 550f) and the speed of burn to be high (such that no unburnt fuel will be exhausted).

Waste oil blended with diesel fuel retards ignition, which is observed by increased emissions and loss of power. Adding gasoline to a waste oil blend advances ignition....increasing the gasoline content up to about 50% will increase the performance of a waste oil blend.

As part of my testing I intend to alter the timing within the electronic PCM of my engine and observe the effects it has on running viscous fuels with high waste oil content. I also intend on purchasing a shaft-mounted dynamometer and fuel flow-meters to give me some actual numbers so that the comparisons will be as objective and unbiased as possible. There is a fear that increasing the timing too much will be detrimental to the health of my engine. From what I understand, if the timing is advanced too far and the pressure peaks before the piston reaches the limit of it's travel on the compression stroke, cylinder pressures will exceed the design limits of the engine and potentially damage parts of the rotating assembly.


Jhanananda

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Re: High performance alternative waste oil blend diesel fuel
« Reply #18 on: August 18, 2012, 06:58:44 AM »
Good to hear that 30% gasoline blends run better on your engine.  Do keep us posted of your results, but do not risk damaging your engine, unless you want to do it just for science.
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)

Jhanananda

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Re: High performance alternative waste oil blend diesel fuel
« Reply #19 on: February 09, 2013, 02:43:44 PM »
My experiments with blending gasoline with waste soy oil has implications here, so I thought I would move my part of the discussion to this thread.

To get soy WVO to run properly on my diesel engine in the winter at 4500 feet (1375m) of elevation has required I keep adding gasoline to my fuel blend, which has taken the blend up to about 50% gasoline to get the fuel blend to run properly below 40F (4c).  Doing so has caused my engine to become hard to start, even on a warm day and with the engine up to operating temperature.  Once the engine is started it seems to run fine, but it tends to leave behind a thin gray smoke.

My problems with running on a fuel blend with a high percentage of gasoline in it has a number of implications:
1) Gasoline at 100% in my region is oxygenated.  Oxygenated fuels here have alcohol added to them at about 10% with a cosolvent, which is typically a polar solvent at about 1.5% of the total volume.  Both alcohols and polar solvents will swell and weaken Buna n and silicon seals.  Diesel engines made before 1996 are likely to have one or both seals in them.  This is what a silicon seal from my injector pump looked look like when it is in the presence of gasoline at 100%.

This is what a nitrile (buna n) seal looks like when it is in the presence of gasoline at 100%.

2) People who have inadvertently pumped in gasoline into a nearly empty diesel fuel tank found their engine overheated, and often blow up.  Most probably the overheating was due to the fact that gasoline has far less lubricity than diesel fuel.

3) Octane is the inverse of cetane, and alcohol is an octane enhancer.  Octane's function in a gasoline blend is to retard ignition to eliminate or reduce engine knock.  Engine knock in gasoline is caused by the diesel effect in a hot gasoline engine. Cetane in a diesel fuel is to advance ignition.  So, one of the consequences of adding too much gasoline in a diesel fuel blend would be to retard or suppress ignition in a diesel engine.

Considering the three above effects of adding gasoline to a diesel engine I was inclined to believe that the seals in my injector pump had swollen; and were causing loss of pressure.  However, yesterday I pumped out the 50-50 soy WVO-gasoline blend and pumped in diesel fuel.  There was about 2 gallons remaining in the tank which could not be pumped out, then I pumped in 20 gallons of diesel fuel, so the 50-50 blend was at 10% of the whole fuel blend, which mean that gasoline in my fuel blend was down to 5%, which made the alcohol content about .5%, which should have made it insignificant. 

The first time I started my engine it was very difficult to start due to the IP still had the previous 50-50 blend in it.  I allowed the engine to idle until it had come up to operating temperature, then I took it on a few short errands.  I turned the engine off at each stop, then after my errand I started the engine again.  I found the engine started right up after each stop.  Also, the engine ran fine, idled fine, and there was no smoke at all evident in my rear view mirror.

The conclusion of this experiment is #1, seal swelling, has to be ruled out, because the engine started just fine after the first start.  Seal swelling should take days for the seals to return to normal size. Lack of lubricity (#2) of the fuel, also has to be ruled out, because a 50-50 blend of gasoline and WVO should have more lubricity than diesel fuel.  There was also no evidence of engine overheating when running the blend. I am left with having to accept that #3 must be correct, that there was simply too much octane in the 50-50 fuel blend to promote ignition in a diesel engine.  This means the ideal gasoline-waste oil blend is going to contain somewhere between 20% and 50% gasoline.
« Last Edit: February 09, 2013, 04:59:43 PM by Jhanananda »
I have run various blends of waste oils and unleaded gasoline since Feb, 2007 in a 1983 Chevy G-20 van with a 6.2L diesel V-8 engine, with a Stanadyne Rotary DB2 IP. I have started the engine with no difficulty on an 80/20 (WVO/gas) blend down to 3F (-16c).  I now run 60/20/20 (WVO/diesel/gas)