I have seen just this same behaviour on glow engines. One of the locals has a 40 size glow engine in which he uses WD40 as a an after run treatment. If he cleans up shortly after flying and the engine is still quite warm it will often start on just the WD40 when he turns it over with the starter.


cheers, Graham

Good day all,

After reading many manufacturer's product sheets, it seems that 2 cycle oil is designed to promote burning which in turn helps remove any carbon build up and helps keep the engine clean.

The local hobby shop has Sig castor, Klotz Benol and Klotz KL-100 oils. All are within a $1 of each other around the $15 mark. I haven't looked at any of the motorcylce shops however.

I thought I would try Amsoil DOMINATOR™ Synthetic 2-Cycle Racing Oil as I can find in a number of local stores. This an API TC type oil

http://www.sea-doo.net/techarticles/oil/oil.htm

The section from the that web site "What does ATP-TC and TCW3 mean?" is very interesting. What I get from reading this bit is that for our air cooled, high performance, engines, the API-TC type oils should be a better match rather thant he TCW3 type.

So, I still want to use a bit of castor oil and may start to use Klotz Benol. In the mean time I have to use up my stock of Sig Castor and so will consider Low ether as a necessity to ensure mixing but will be using the Amsoil syntheitc 2 cycle oil in the same mix.

I am hoping to do some more test running today with 10 and 5 percent Ether mixes, yard work has to be done first

Any other thoughts on oils? what, why, percentages?

cheers, Graham in Embrun near Ottawa Canada.

Good afternoon all,

Got the yard work done and managed to spend some time running a diesel.

All tests done with my "test" engine, a 40 year old re-built PAW 2.49 DS engine with a Kavan 9x5 prop.

Ambient conditions where Temperatur 22.6 degrees C, 42% relative humidty, and 1017 mb pressure.

Test #1

10% ether 10% castor 10% Amsoil INTERCEPTOR synthetic oil 2.5% Amsoil Cetane Boost and 67.5% kerosene.

Only prime was finger over venturi and 3 flips of the prop. Needed compression set 1/4 turn higher from running postion in order to start. Ran pretty much like the 20% mix but compression setting was bit more sensitive. Consitent rpm about 9000 and head temperature between 185 and 200 degress F . My last test results showed the engine running much cooler on 20%, 130 - 160 degrees F. I now believe it did run cooler on the 20% but not that much cooler. Those lower measurements I belive are in error and attributable to my inexperience using my new remote thermometer; I am much more consistent with postion when taking readings now so temperature readings should get more reliable.

Test #2

5% ether 10% castor 10% Amsoil INTERCEPTOR synthetic oil 2.5% Amsoil Cetane boost and 72.5% kerosene.

Only prime was finger over ventrui and 3 flips of the prop; engine was left to cool after first test runs. Also needed compression set 1/4 turn higher from running position to start. Ran pretty much like the 10% mix but compression and needle setting was a bit more sensitive. Gained about 100 rpm over the 10% mix about 9100 rpm and head temperature up a bit at between 200 to 220 degrees F.
Compression could be adjusted from too little to too much in one honest half turn of the compression screw. Since the compression screw this amounts to a movement of contra piston of approximately 1/64" (.0156" ). That's a change in combustion volume of approx .004 cubic inches if my math is right (cylinder bore is .595"). How that relates to change of compression ratio I couldn't say at the moment. I will have to do a bit more reading and figure that one out too.

Going from 30% to 5% ether, compression setting became more touchy as did needle valve setting but not unreasonably so. The temperature of the engine also increased but again not unreasonably so. Also, running the 5% ether mix sure didn't smell the same as the 20%+ mixes.

There is nothing new in these observations as Andy has already shown the same basic pattern in his test reports. This excercise was very educational and I think I now have a better understanding of these wee diesel (compression ignition) engines but there is still much to learn.

I am beginning to wonder if high ether was always used in the old mixes to account for evaporation over time by giving a good bit extra to ensure the fuel would stay good for a long time.

And oil content. As you can see I am now using 20% total oil and it looks like the engine is not having any issues that. My next set of tests will be to use 15% total oil 5% castor 10% Amsoil INTERCEPTOR synthetic and go through 20%, 10% and 5% ether. After that will be changing the amount of Amsoil Cetane boost. Too many combinations and permutations to think about!

I am also a convert to using starters with diesels. I truly believed the old wives tales. These old tales do speak the wisdom of being careful and thoughtful of what you are doing. I think if continue to approach these engines with thought and care then I should never have a problem with breaking parts with the starter. I will be sure to let you know if I do.

This has all been a very interesting thread and I hope I have been able to add to it's overall value.

cheers, Graham in Embrun near Ottawa Canada

Graham,

Your 10% run sounds very much like how my PAW 19 used to run on 10% ether fuel for sports c/l flying. For cold starting it needed a fraction of a turn in, but once warm would re-start on the running compression without any adjustment.

Compression setting on the low ether fuel was more sensitive than with the normal 1:1:1 mix, which seemed to have quite a wide range of viable compressions for usable power.

I never went below about 25% oil (may have experimented with 20%).

Regarding Redex, my understanding is that is an upper cylinder lubricant and detergent, ie. it both assists with piston/liner lubrication and with de-carbonisation.

Is it really necessary? I don't think so, but it doesn't hurt, and definitely seems to keep carbon build-up in check. It is also fantastic for freeing up gummy engines - a little bit down the venturi and the engine becomes much freer to flip over.

cheers,
Colin

Hello Graham, et al:

My I offer some suggestions to help you with the No Ether Fuel?

As you have mention there are many possible combinations of fuels, Cetane boosters, and oils, but if you sit down and make a list of these combinations it is not really that large if you consider the fact that the idea is to be able to make a “no ether fuel” on most continents of the world. I’d like to list some of the possible components and also list their pro’s and con’s.

First we need to look at what goes into our diesel fuels.

1. Fuel
2. Oil
3. Ignition enhancers (ie. Cetane Boosters)

Next, we need to discuss the Energy Density (ED) of these fuel/oil/Cetane booster combinations. What do I mean by Energy Density (ED)?

Energy Density (ED) = is the amount of store potential energy to do work, or BTUs divided by volume, or BTUs/volume, yet another way of looking at it is the BTUs per drop of fuel.

Other definitions required for this discussion:

Cetane = ease of auto-ignition from compression of a gaseous mixture of fuel/air.

Compression Ignition = the required compression level (i.e. 20:1 or higher perhaps) of a fuel/air mixture to create the required amount of increase in the air temperature to auto-ignite your fuel/air mixture. You must consider the rate of compression not just the compression ratio. Thus if you use an electric starter you will have a much higher rate of heating, enabling you to start the engine much easier. This is a very important concept that Andy has proven with the use of You-Tube movies and his small starter. The electric starter helps to increase the rate of temperature rise of the fuel/air mixture with in the cylinder.

Fuel Viscosity = Fuel with high Cetane ratings usually are more viscous and are more difficult to atomize and vaporize. Solids and liquids do not burn! They must be vaporized or turned into gases and combined with an oxidizer (air) to burn. So if the fuel is viscous it is more difficult to burn than a similar lower viscosity fuel. This is very important in little engines. The electric starter greatly assists in atomization of the fuel/air mixture helping in startup yet again. Please note, Ether and Hexane as exceptions, they have a high Cetane and great ease of vaporization, but very low ED.

Okay, now on to fuels of possible use for your experimentation.

HEAVY FUELS,
Kerosene
Auto Diesel #2 and #1
Jet A
Deodorized home heating Kerosene
Lamp oils

“Special Heavy Fuel”
Bio-Diesel (Keep an eye on this one, since I think it is a very good choice)

These fuels all have High ED and High Cetane rating, and High Viscosity and low Volatility.



MEDIUM FUELS,
Coleman and Ozark Camper Stove and Lantern fuels.
BBQ Lighter Fluid

(Ozark Camper Stove Fuel is WalMart’s brand and cost about $3.80/gal USD)

These fuels have modest ED, modest Cetane rating and Low Viscosity, modest Volatility.



LIGHT FUELS.
Ether
Hexane

These fuels have low ED, high Cetane rating, and low Viscosity, Extreme Volatility, but also have high cost and other negative factors.

Okay now what fuel to use?

If you want a “no ether fuel” you need to consider a substitute for ether which is a good Cetane improver and a low viscosity, highly volatile fuel that is easy to vaporize.

Okay, then what happens when you remove the ether? The viscosity of the fuel goes up, the ED rises a great deal, and the volatility of the fuel goes down. Remember ether is very volatile, low ED, low viscosity fuel. Okay, “so what” you say, well the metering system is now not calibrated for this fuel, the needles get very sensitive and the idle is not as low and smooth.

How do you fix this problem?

I would suggest that you use a heavy fuel blended with a medium fuel to decrease the ED of the fuel, This will also lowers the viscosity allowing for better atomization and vaporization of the fuel.

Perhaps a 50/50 mixture of one of the Heavy Fuels with Medium Fuels would work.

It is important to match the ED of the original fuel design for the engine. If you are using a PAW engine the carb is set for diesel use and has a smaller throttle body bore, which is preferred. If you are using a converted glow engine then you must consider reducing the throttle bore in addition to lowering the ED of the fuel.

Glow engines burning standard glow alcohol fuels may require a fuel to air ratio in the region of 10 parts air to one part fuel. A Kerosene and oil mixture may require a mixture on the order of 20 parts of air to one part of fuel. Now you get the idea. The ED must match the design of your fuel metering system. I would suggest that you try straight Coleman or Ozark fuel or BBQ Lighter Fluid for a Glow conversion engine as the fuel component. Since your ED will match the metering rate of this oversized throttle body much better, but you will need more Cetane booster to recover the lost Cetane rating of these fuels.

The trick is it to lower the ED of the fuel without lowering the Cetane rating of the fuel, but if you have a limited number choices, so you must use the Cetane booster to recover lost Cetane ratings. A Very Important Concept!!!!

Now you need to consider the Cetane Booster, which I will only talk about the Amsoil Cetane Booster since it is safe to handle and can be purchased in Europe and Australia too.

I would suggest that you start with a mixture of at least 2% Cetane booster and gradually increase this percentage up to 15% in initial tests to discover the effect of excessive booster. I recommended to Andy a run of 10% and he confirmed that it did not harm the engine.

You need the Cetane booster since you have removed the ether from the mix. How much I don’t know, but it will not harm your engine, just back of the compression ratio some if it sounds odd. We could all benefit from a good test.

Oil:

Okay, this is dangerous territory since everyone has a favorite and their own ideas, but here are some facts.

Synthetic oils are not going to burn and increase the ED of your fuel, which is very good. They are a dilutants, like the medium grade fuels. They will not carbon up your engine and they are low viscosity in comparison to Caster Oil . Some synthetic oils are very reasonable priced I.E Cool Power cost $7.50 per QT USD.

In summation: Synthetic oils are low viscosity (good), low ED (good), will not burn to carbon (good) and are required in lower concentrations (good), and can be found for modest cost. Very good. I’d strongly suggest these oils!

Non-Detergent Motors oil are good low cost choice and work well, but they increase the ED and do burn to a degree within the engine.

Castor oil is okay, but gums up engines, burns to carbon in the engine, and increases the ED of the fuel, all of which are not good. Plus it is very costly.

I would suggest Morgan’s Cool Power (green) oil, Klotz 200, or some of the Amsoil products like Interceptor, but I don’t think the Saber version from Amsoil will mix with Bio-diesel. See below comments:

Okay we have just about made it to home plate now. So here is my best suggestion;

Bio-Diesel (BD) is low cost fuel, easy to make or now getting easy to buy in many towns worldwide. It is very safe, since you can eat it. It has a very high Cetane rating. As an example Kerosene has a Cetane rating of approx 45 and BD can have a Cetane as high as 60!

Look here to see how to make Bio Diesel fuel: http://journeytoforever.org/biodiesel_make.html

You most likely will need to use synthetic oils in combination with BD and I don’t know if Cetane booster is required, which would be really nice news. BD is made up of long unbranched chains of hydrocarbons, which is great news, plus it has a great deal of oxygen attached to the molecules, which maybe wonderful news for our purposes. It may work like Nitro in our small engines to boost combustion efficiencies. It has modest viscosity so it may meter quite well. I don’t know if it will mix with the Medium Fuels without the correct synthetic oils, but I’m sure it will mix with the use of Cool Power or other synthetic oils. It burns clean with a very pleasant odor and almost no smoke. It has a nice clean odor in general terms, unlike Kerosene, or Jet A. It cost about $3.50/gal USD.

One more idea I passed on to Andy was using Pre-heat to get the engines up to running speed temperature at startup, so that you don’t have to adjust the compression screw. If you make an iron out of steel tubing with a small-insulated handle it can be heated in the field with a torch and set on the cylinder. This preheat will allow the engine to start instantly and not require any adjustment after you initial setting have been make to the engine.

Resistive heaters are also possible using small heating elements from portable soldering irons.

The entire portable soldering iron: http://www.starkelectronic.com/wahl.htm
The tips are only $6.50 each and run on 3 volts: http://www.starkelectronic.com/wahltip.htm

Use them sort of like a glow plug, but I’d call it a preheat element to keep from confusing the topic.

I hope this information is helpful,

Kelly

Mercury No. 6 mystery. I have a reprint of Bowden's "Diesel Model Engines" (1951) where he mentions a fuel called Mercury No. 6. (on page 98) It was a NON-ETHER fuel composed of 6 components that, according to Bowden, ran engines quite well. He mentions that all 6 components were necessary or the fuel would not work.

Does anyone have any idea what was in this mysterious "Mercury No. 6?"

George

thanks Kelly, plenty to think about.

I have been looking at biodiesel as it is an interesting topic which I thought might have an application to our needs. I haven't found any place locally that sells it yet but the process to make is not too complicated. However, having to "cook" up a batch of fuel to go flying seems like an awful lot of work. Still, the process is interesting and the results might just make it worthwhile.

I had never thought of mixing something like the Coleman type fuels (Naptha ?) with kersoene. I will have to give that try.

George:

Mercury No. 6 - never heard of that one, maybe someone can uncover some details on that one.

I did run across this interesting bit on fuel for F2C Team Racing. Seems many years ago the Russians where using Tetra Ethyl Lead in their Team race fuels which allowed them to run higher compression. Some enterprising fliers found a substitue in ferrocene, (dicyclopentadienyl iron),

http://www.go-cl.se/fc.html

Andy has been pretty quiet of late. I wonder what he has been up to in his testing.

cheers, Graham in Embrun near Ottawa Canada

Hello Graham,

I would suggest you stay away from Tetra Ethyl Lead, since it is an Octane Booster, which is going in the wrong direction.

An Octane booster is used to DECREASE the ease of Auto-ignition.

A Cetane booster is used to INCREASE the ease of Auto-ignition.

This entire subject gets mucked up in modeler minds for several reasons.

1. We are using a hybrid engine, not a true diesel engine.
2. We are adjusting the compression to affect ignition and ignition timing.

Please let me explain.

Our Glow/Diesel model engines use a carburetor for air and fuel induction. The fuel/air mixture (FAM) is drawing into the engine via differential pressure (Vacuum). This FAM is atomized and then vaporized within the engine and then compressed.

In a normal glow engine the glow plug is the source of ignition, the physical characteristics of the glow plug determine ignition timing. I.e plug temp, number of coils of the wire, wire diameter. The Compression Ratio (CR) also determines the ignition point as well as the load on the engine. I.e the prop size and shape. These factors are quite limited in adjustment, so a major change in ignition timing is not as easy to achieve as with the model diesel engine.

In a model diesel engine the induction system works the same as in the glow engine, but now we have a contra-Piston or just a simple disk-plate that has been adjusted to meet the pressure/temperature needs of our fuel. Thus we can also adjust the ignition timing by adjusting the CR of the engine. You must increase the CR of a cold engine for startup. This is to help achieve the require CR to reach auto-ignition temperatures. As the engine reaches a stable temp we must decrease the CR, which affectively reduces the timing of the auto-ignition. The wonderful part of all of these matters is that fact that a model diesel engine can swing a huge heavy prop to create a great deal of low velocity thrust, much like today’s modern electric park flyer aircraft/motor combinations. It can also swing a small high speed prop by increasing the CR which advances the timing.

In a real (normal) diesel engine, fuel does not enter the engine via the induction system. There is no carburetor, only an air-valve, just a butterfly valve to admit air. A direct injection fuel pump injects the fuel into the cylinder at exactly the correct time to facilitate, complete vaporization of the fuel, which does take a few milliseconds to occur. The fuel is injected into the cylinder that has already compressed (only) the air to a very high temperature and pressure. When the fuel hits this very hot environment it goes from a liquid to a vapor and then mixes with the oxygen within the cylinder and undergoes auto-ignition. The timing of this engine can be adjusted by the fuel injection pump and this does change with RPM and varying load changes, often using centrifugal weighs within the injection pump system. Sometimes for startup, the timing can be altered manually in some engines.

The important part of this discussion is not a treaties on how diesel engines work but to show the fact that our model diesel engines are not truly diesel engines. In fact they are working in a very difficult environment. We are asking them to detonate, or you could say run in a pre-ignition mode continuously. Now if you ask your auto engine to run like this it would not last long. It would be constantly pinging. What we are doing is asking our little engines to ping, or auto-ignite every other stroke. We should consider that they would want a fuel that is easy to auto-ignite, so that the CR can be maintained at a lower ratio. Cetane boosters give the engine this edge. They don’t all work the same, but for a simple explanation you can consider that they allow the hydrocarbon chains in the fuel mixture to fracture at a lower pressure or lower CR.

Octane booster like Tetra Ethyl Lead are added to fuel to keep the fuel from falling apart, to help the fuel hold up to a higher CR, or allow an engine to be run at a more advanced ignition timing. In a gas engine we are compressing both the air and fuel (FAM) as the piston reaches top dead center we don’t want the mixture auto-ignite without control, we want it to wait until the sparkplug fires. This control is critical, so in WW II it was found that high levels of Tetra Ethyl Lead would delay this auto ignition and thus high-octane aviation fuel allowed the Allied Forces to produce very high power to weight aircraft engines. Even today Aviation Blue 100 low lead has a huge amount of this very harmful and dangerous fuel additive, which was remove from car fuel in the early 1980’s.

In summation: our hybrid model diesel engine are not really diesel engine in the normal sense, since they compress the Fuel Air Mixture together during the compression stroke and not direct injected. We also must consider that our engine must be lightweight and thus we are forced to use as low of a Cr as possible to achieve Auto-ignition. Thus we need either ether or some other substance mixed with our fuel to increase the Cetane of the fuel. Just the opposite of what most folks think when we have such discussions. Everyone is so use to hearing Octane they get confused. Stay away from the ketones like acetone, lacquer thinners, and other things like alcohols since they have very high Octane.

Keep in mind that you are trying to achieve a low ED (energy density) fuel that is easy to auto-ignite. This is not easy, but it can be done. NO Black Magic mixes are needed, no voodoo or special engines or equipment, just a bit of simple testing using a good engine with a small high speed electric started and perhaps an iron to preheat the engine. If the mixture is some sort of secret mixture then it is either dangerous, or the components are difficult to find. Model diesel engines have been around a very long time and there are few things that have not been completely tested in the past, but Amsoil Cetane Booster is a very concentrated high quality product that is relative new, so this combined with simple things like Coleman stove fuel (yes this is primarily naptha) may work quite well.

Give it a try, you can’t hurt your little engine if you work slowly and make small changes to the mixtures. We would all like to hear your test results.

I hope this is useful and interesting.

Kelly

There is no butterfly (throttle) valve in injected diesel engines.

I agree our engines are complicated and some settings interact with others. HP is very dependent on CR. Higher CR results in more power. This is how model diesels make more power than other fuel types(though not in all cases). We could get more power but timing is advanced too much and problems result. Team racing is an application where power is important. Increasing CR will improve power and fuel economy. They do what they can to improve those two things. Delaying ignition and shortening combustion time is something they benefit from.

RingWinger, you mention energy density of fuel. Is this BTU/Lb? Most petroleum based fuels are in the 17-19,000 BTU/Lb range. Not enough variance to be concerned. The mass density varies quite a bit, but energy density doesn't.

We know that we don't need ether in the fuel for autoignition at reasonable CR. I'm running my engines on etherless fuel at the same CR as ether mix. Why is this if ether's cetane rating is near 100 and we are mixing 35% typically?

Greg,

Yes, You are correct, there is no butterfly valve, my mistake. Thank you. You adjust engine speed in a normal diesel engine by direct control the fuel pump.

Energy Density in my discussion is somewhat my idea of a way to illustrate the concept of the amount of energy within a give volume of fuel.

Density is normally defined as mass/volume or in some cases weight/volume. Since we are working with the concept of Potential Energy stored within a fuel I choose to use the BTU/volume idea. I hope this was not confusing. It is not exactly correct, but it allows me to get the concept of how much energy is available within a specific fuel. Mass density does vary a great deal and this is the factor that I feel will help other blend a mixture that will match various engines. I have somewhat blurred the concept it appears.

Agreed, HP is depended upon CR. If I remember right if you increase CR by 10% you can expect a 10% increase in power and a 20% increase in heat. This assumes that the engine will handle these increases? Exactly right we get a bunch of power out of the little model engines. I’ve always wondered if this increase is due to the fact that most of the time we increase the diameter of the prop with the use of a diesel engine. Since a very small increase in prop diameter will make a large increase in thrust.

HP maybe lower in a diesel, but torque is larger. Since the RPM is lower the HP is lower, but a large prop indicates that an increase in torque was achieve. Much like the idea of a tractor using larger traction wheels in the farm fields.

I can’t address you last question since I don’t understand exactly your drift. Perhaps you could re-phrase this question and I’ll try again.

Thanks for catching my error with regard to the throttle valve. That was a dumb mistake.

Tell us about your success using “no ether fuel” please. Have you had any luck?

Regard,

Kelly

[quote]ORIGINAL: gkamysz

There is no butterfly (throttle) valve in injected diesel engines.

Actually some diesels do use a butterfly throttle.
Basically diesels have 1 of 2 types of govenors in the fuel system, 1/ constant speed,2/ variable speed. things like tractors, generators, dozers and the like have constant speed govenors( yes these can be adjusted in speed too , but they will hold a constant speed irrespective of load), wereas cars/ trucks are fitted with variable speed govenors- basically the spring tension in the govenor is adjustable by a linkage from the accelerator pedal(this type of govenor will allow the speed to vary dependent on the load). Some use a vaccum linkage ie there is a butterfly valve and venturie to create a variable vaccuum which works on a diaphram on the fuel pump to change the govenor settings, Nissan and some Isuzu diesels are some that use this method.
Stewart

If the current production glow engines are designed for 7-8:1 CR and we run them at 2-3 times that as diesel conversions the mechanicals aren't an issue. So I think we could still run higher CR to make more power if possible witout worrying about engine failure as long as oil is chosen accordingly.

Energy density for fuels, especially aircraft, is specified as BTU/Lb. Diesel fuel economy as measured in cars is always miles per gallon. Nobody bothers that diesel has a 20% advantage because it is heavier than gasoline to begin with, besides gasoline and diesel is sold by the gallon not the pound. By weight, heat value is within a few percent. You must specify. Science teachers tought me one thing I'll never forget "the units ARE important". Air is burned with fuel by mass ratios not volume ratios.

Torque may be greater but HP does work. So less HP means less work. The issue here is that a larger diameter prop may be more efficient than a smaller prop at the same power in a particular installation. So less HP could result in similar or even better performance. This isn't a bad thing. In an airplane the prop is the "transmission" matching the diamter and pitch is like selecting proper gearing for a car.

About the ether. If the ether has a high cetane number (CN) of ~95 and we are mixing 35% of it with kerosene which it seems is near CN 40. What is the final CN of the fuel? I would think it's higher than the 2% Amsoil mix, but they run at simliar CR.

The etherless mix I've tested is castor, kerosene, and Amsoil cetane boost. The details are a few posts back. It runs well but I haven't been successful in a cold start on this fuel yet. I haven't tried any more since that day becuase of a cold or something I have going on.

Greg,
" About the ether. If the ether has a high cetane number (CN) of ~95 and we are mixing 35% of it with kerosene which it seems is near CN 40. What is the final CN of the fuel? I would think it's higher than the 2% Amsoil mix, but they run at simliar CR."
Combustion is a complex thing, my take on your findings are even though the cetane No of the 2 mixes maybe different, but still yeilding similar results is due to the differing burn rate of the 2 fuels, the cetane no determines the start point of combustion then the composition of the fuel molecules takes over to determine the burn rate. That is the higher cetane fuel may start burning sooner but actually burn slower than the lower cetane fuel therefor they both require the same CR to get optimum performance.
Aditives like amyle nitrate I beleive dont change the cetane No but increase the burn rate, this is why adding too much makes compression settings go crazy, you need suffient compression to instigate combustion but the burn rate is too fast requireing the compression(ignition timeing) to be backed off, but now its falling behind the cetane of the fuel.
Ignition improvers work in different ways too, some increase in burn rate as pressure increases wereas some reach a pressure were the burn rate starts to drop off.
An interesting site on burn rates is :- http://nakka-rocketry.net/ allthough the fuel is different the studies on burn rates and the use of different burnrate modifiers is the same in principle. Read the sections on burn rates and burn rate modifiers/enhancers I beleive it will give you more insight into whats happening in the diesel fuel mixes.
Stewart

Hello Greg,

I fear that this discussion is fragmenting into some rather odd directions, off course from Andy’s intent to find an etherless diesel fuel. My use of Energy Density was to help other see that various fuels do contain more or less energy and also have other characteristics such as viscosity, Cetane rating, and yes as you pointed out various mass densities. I’m not trying to pretend to be a Science Teacher, just encourage others to mix up various mixtures of safe and sane readily available common fuels and oils.

This thread could quickly degrade into a mash of odd physics debates, which are of little interest to me. I’m only interested in encouraging others continue on your happy course of a good simple “No Ether Fuel”.

Yes, I did see your test result. Very nice work and thank you for experimentation posting.

I don’t know the answer to your questions. I’m not a chemical engineer.

Yes, cold starting appear the problems. Take a look at this like: http://www.dstarengineering.com/news...tors_main.html

D-Star has a little generator set that is only about 5 inches square that put out about 50 watts. It runs on JP-8. I spent a great deal of time digging around on the Internet and found that it uses just a bit of oil added to the fuel. It also has a 1- minute preheat cycle for startup using some sort of resistive heater. I found this information about 1 year ago and passed it on to Andy. Andy called D-Star and talked to the owner.

It was this device that peaked my interest in a “no ether fuel” and I suggested to Andy the use of some sort of Hot Spot within the engine. Andy did test this feature and posted it on RCU. Do a search for Hot Spot.

I did not know about the other diesel system with an air valve, many thanks for that info.

Again, can we please get back to find a “no ether diesel fuel. I apologize for not using exacting descriptions.

I’m done,

Kelly

Kelly,

Thank you for all the info, it was very informative.

Kelly, I'm not trying to be agrumentative here. It's just that the physics and chemistry is important. I think Stewart hit on the point that I was thinking about and what was mentioned on the Goran Olson site. Team race guys want to delay ignition so they can run a higer compression but also burn the fuel quick enough to get the most power out of it. That's why they use the various additives in the fuel. A chemist well versed in this may give us the answers we need. I would like to run higher compression ratio to make more power. At this point I think a fuel with a high cetane rating but higher autoignition temperature than kerosene would do the trick, if all it's other properties make it useful.

I did find that D-Star was using 3% oil in a government bid or something. I did not see the preheat requirement. DDD had a proposal for that contract too.

I used to think that the glow engines we have can't survive high CR. I don't believe that any more. Even so, it would only take a slightly larger crank and rod to do it.

Greg,

I see I was wrong about the compression adjustment on your Enya 41. Not going to keep it? Is your only compression adjustment the head shim? What's the glow plug looking thing?

How about posting the instructions for the engine?

http://www.nrel.gov/vehiclesandfuels/pdfs/sr368051.pdf

Andy, if you didn't find this in your searching, this has a lot of information about CN of different chemicals. Finding a chemical that is cheaper and easier to handle than ether still isn't easy. I think the kerosene and octyl nitrate blend is good as long as it starts reliably. Diesel No.1 should be extremely similar..

It seems that there are chemicals that have high cetane numbers but also very high auto ignition temperatures. Castor oil is one and Biodiesel is another. If the in cylinder temperature doesn't get hot enough it won't fire, so CN isn't the only thing we are looking at. In an injected diesel cylinder temperatures are high enough to run B100 without problems, but I don't think it will work in our engines. The link above says the ether we use has a CN of 140-160.

Kelly, Greg, Graham, Stewart and all,,

A great many thanks for the wonderful input.

Vexing local issues have had me distracted for a bit. Those are receding into the background and all this excellent input and data has got me back on track. We are learning a lot. In the end, it appears that I got quite lucky in the use of (1) Benol from Klotz, (2) my particular brand of kerosene, (3) Amsoil cetane booster.

Using my benchmark .15, I tested the Aviation oil, Amsoil, MEKP, kerosene, lamp oil, Coleman fuel, naphtha, JD ether, all in various combinations and percentages, some 16 in all. Reviewing my rough notes, a number of conclusions have been drawn. First, an appropriately sized starter can be used to great advantage, if used properly. Secondly, ether is good. Some or lots can help. It smooths out the engine and allows the top end and idle and transition to be found and maintained more easily. However, it's not absolutely necessary. It IS if you're running traditional diesel engines with the required starting and handling procedures. As noted, Benol's apparent high cetane number and ease of mix with kerosene helps a lot. Something about the two molecules complementing each other. Amsoil has been found to be quite superior to MEKP. I tried the local brand of lamp oil compared to the local kerosene and the lamp oil was inferior. Adding Coleman or naphtha hurt. The engine would not start. CP was flush, full down and no go. It MAY have started if we didn't have the copper gasket running interference. But that would have been an extremely high compression ratio.

Taking off the head revealed that the CP was flush with the bottom of the carrier. So a simple disc was installed and with a bit of fussing, the engine fired off and ran. Once up to temperature, it ran as well, or even better than with the head. This could be due to the elimination of that bit of clearance between the carrier and the CP. Something like the threads of the glow plug in a glow engine, interfering with combustion. The flat disc provides a very pure, and extremely small, combustion chamber. Keep in mind that in this .15, the piston does not quite reach the top of the cylinder deck. Add in the washer AND the very small slop in both ends of the rod and some of the clearance in the crank to case fit and we have, what appears to be, virtually no combustion chamber at all. At least in comparison with glow. In this case, at least some (10%) ether helped a lot.

There are some idle and throttling issues without ether. A two needle throttle, as in the .40, seems to help. A three port, (AME) compared to the five port, (Big Mig) was found to throttle equally well. No advantage in this area was found, unlike our glow experience with the .06.

At the end of the tests, the engine was torn down. The top of the piston was carboned up considerably. A rough, gritty-like carbon deposit had to be scraped off. The conrod, on the piston end, developed some slop, the other end was still good. The stain on the top of the piston shows how efficiently Norvel's porting delivers fuel into the combustion chamber. Kelly's suggestion to use Cool Power oil may eliminate some of these issues. Got some on order.

It's my thinking at this point, that some unique aspect of engine design, along with specific ingredients, can make a no ether system work well. With all the diesel engines out there, traditional and modern, we just might stumble on that magic combination of high power, ease of start and perfect throttling that we want, on an all kero fuel.

If everyone had a local source of ready to go diesel fuel, none of this would matter. But that's not the case with the majority of diesel lovers. If fuel wasn't such an issue, I'm sure that of all those that love engines, many more would be attracted to this truly unique experience.

Good day all,

Good to see your comments from your tests Andy. Most of conclusions seem to be falling in line with yours.

I do think that some synthetic oil in the fuel would be beneficial as Kelly and others have also mentioned. It should help keep the engines cleaner (less carbon). I have started to try an Amsoil 2 cycle oil as it is available at Canadian Tire so is easily obtained. I don't know about CT in Timmins but if the local stores here have it then it should be in the store there as well.

I found an interesting article in the Australian Control Line News issue 73 on F2C fuels (FAI team race). Again with reference to Tetra Ethyl Lead and Ferrocene. Not something we should be playing around with but an interesting read non the less.

http://dkd.net/clmodels/acln/acln73.pdf

There must be hundreds of articles/reports on F2C fuels etc that would be interesting it is just a matter of finding them; most undoubtedly buried in old issues of model magazines and organizational newsletters.

Interesting note about the F2C fuels is that they still use high ether content - 30% or so as they don't (can't) use a starter and require fast single flip restarts on hot motors (and they won't mess around with compression or needle setting while do so). So, their needs are different from our own but still makes for interesting reading.

In light of your comments on mixing naptha with the diesel fuel, I think I will pass on Kelly's suggestion to try that for the time being. You didn't specify percentages so it is hard to second guess whether you used a lot or a little.

I did find a local source for vehicle BioDiesel. B20 is what they sell - 20% BioDiesel and 80% petroleum diesel. I am going to give some of that a try. I am hoping I can pick some up before the weekend.

I am glad I picked up a graduated cylinder. it makes it dead easy to mix fuels with good accuracy and repeatability; sure beats my old recycled roughly marked Sig Dope bottle.

cheers, Graham in Embrun near Ottawa Canada.

Graham,

Re the naphtha. I tried a little and then a lot. Time constraints forced me to just spike regular fuel with a bit and then a bit more. I did this with ether based and non-ether. I know that this dilutes all the other ingredients but this was just a quick test to see if it would start. In no way is it definitive. I'm only speculating, but it could be that with just a bit more compression, we might have had a start. And that higher compression may be just the ticket for improving the idle. My CP design may just have prevented me from getting a good result.

Going up to CT now to check to see if they've got the Amsoil 2 cycle. Good tip. I'm sensing that this, or Cool Power oil, might be that missing, magic ingredient, in this exercise.

For this kind of fun, a graduated cylinder is a must for accuracy.

Looking forward to the Biodiesel test.

Gentleman,

Wonderful work Andy!

We now can start to see what will work. I half suspected that the Naptha may lower the Cetane to such an extent at it may not work, but it may work with Bio-Diesel.

I called our local fuel dealer, which I found via the Internet, he was very happy to supply me with a 1 qt of B100 Bio-Diesel fuel. I have to wait until later next week to pick it up. The fuel cost $3.20 per gal USD. He also told me that it has a viscosity very similar to Diesel #2. He also promised me a copy of the spec sheets. He confirmed the fact that this fuel burns much cleaner that Diesel #2. He also claimed it had a higher Cetane rating than Diesel #2. I hope the spec sheet confirms this matter. From my evaluation of various web sights the Cetane rating is very dependent upon the source of the original veggie oil. Palm oil being the very best, and other seeds like canola in the middle range.

Next week I’ll mix up a batch and give it a try in a PAW .19 ball bearing motor.

If you do a search on RCU for the keyword “Biodiesel” you will find some interesting reading. Some claim that this fuel works well, which is encouraging. One of the good points I read was the fact the exhaust smelled like French Fries. I think this is a nice occurrence, and sure an improvement on kerosene.

I don’t know if B-20 will work well since you’ll only be getting a 20% concentration of the bio diesel, but it would be fun to try. Ask the folk that sell your B-20 if you can get a sample of B-100, my dealer was very interested in the fact that I was going to use it in a model engine. The industry is always looking for ways to promote how safe and clean a product like Bio-fuels can be represent to the public. You maybe able to secure a sample from the original blender just for the asking.

I thought I’d pass one other experiment on to all of you to illustrate how the Cool Power oil worked for me. This does not apply to our current fuel experiment directly, but here it goes.

I wanted to mix 50% normal glow fuel with 50% Coleman Stove fuel. It would not mix just my adding the two together, or with the addition of Amsoil Saber synthetic oil, but when I tried Cool Power (green) it mixed and stayed mixed. I ran this mixture in a Tower .75 engine and as you would guess the needles where sensitive, but it ran great. It ran very hot, but I did not have a way to measure the increase.

Not all synthetic oils are the same as far a blending with various fuels, thinners etc.

The Cool Power oils does not leave a trace of carbon in my TT .46 engine using just methanol and oil, but when I was using a castor mixed with synthetic oil in a 50/50 ratio it burned very black, hard deposits which were hard to remove. It also gummed up the engine after about 10 gallons of fuel to the point the carb was very sensitive and the idle was very hard to hold and control. I had to give the engine the hot antifreeze treatment in a slow cooker pot. Now with the use of Cool Power I don’t have any of these problems, plus I only use a mixture of 15% oil.

Andy, that is interesting that a simple flat disk work the best, I’m wondering if a copper disk or other metal disk insulated on the outside of the engine would help create the desired hotspot. Perhaps it’s just the fact that the disk represents a smaller heat sink and a concentrated area of extra heat to light off the fuel?

Any ideas? Can anyone think of an alloy that would interact with heavy fuel to work as a catalyst?

It appears that the D-Star engine only has to run at full power at all times thus idle is not a concern making it much easier to design and operate. One speed, one mixture setting and one compression setting. If you only operate like a generator at a very specific speed range everything can be programmed for this one speed zone.

I was able to find a series of lectures on the Internet given by several designers of MAV aircraft, in this forum D-Star talked about their little diesel engine. In this lecture they mentioned many interesting things, and I believe this is where I hear the fact that the generator set used a 1 minute preheat before startup. This make perfect sense if the are running JP-8 with a 3 % oil mixture. Wow, not much oil in that mixture!!

The Army has a One Fuel requirement, which happens to be JP-8. They want to get rid of batteries in the field too, so this little diesel engine is to run on JP-8 plus a bit of oil.

You can try to find these lectures by searching for MAV aircraft and D-Star Lectures. I sent Andy an email with this link attached last year, so he maybe able to find this data too. It as audio only.

They also built an engine for a little VTOL aircraft called Kolibri. It appears to be classified and very little info can be found on this aircraft. It uses one of their little diesel engines to extend the flight time to the maximum. D-Star has been able to get this little engine to idle, so there is hope for us too.

Do a search for “Darpa Kolibri”

Almost all of the links do not work for this device, which indicates that it must fly very well. I have found only two photos within PDF documents that show the craft. So I can’t cut and paste the photos for all of you. I was unable to see the motor in the craft.

I found this below. Note: they say multi-fuel engine, that is one of their diesel engines. I don’t know what other fuels it can handle?

Lutronix Corporation "Kolibri" micro-helicopter The Kolibri micro-helicopter built by Lutronix Corporation of Del Mar, California. The Kolibri (German for "Hummingbird") was larger than the other DARPA MAV prototypes, with a weight of about 300 grams. The Kolibri was built as a cylinder with rotors at one or both ends, using vanes moved through the rotor airflow by piezoelectric actuators for flight control. It was powered by electric motors or a tiny, highly-efficient multi-fuel engine developed by a company named D-STAR.

Andy did you happen to ask the owner about that preheat during your conversation?

I’m thinking that a CL engine would be very happy with Wide Open Throttle on No Ether, but it maybe difficult to achieve a good idle without ether. D-Star may not care or DDD for that matter. Just fire that dude up and make electricity.

Kelly

Four strokes must be a bit different. I ran two engines and both behaved similarly. I noticed no problems with idle or transition in my engines. The idle was fantastic on either fuel. On etherless they ran better at full thorttle. I was getting preignition with ether and had to back off the compression and power was reduced. With etherless I did not have this problem. I hope to get a chance to fly on etherless mix soon.

I have absolutely no compaints about the running qualities of the etherless mix I used. Starting is a problem I'm trying to overcome.

My opinion is that biodiesel without ether is not viable. The data I've seen says it boils at over 300C and flash point is 150C. Flash point of No2 diesel is 52-90C. Kerosene, Jet-A, No1 diesel has a flash point of 38C. If you have ether in the mix to light it I think B100 will run in our engines. If enough of it vaporises at the tempertures we see in our engines it might even burn most of it. But it's not any cheaper than kerosene so if we need ether, why use it?

I just received my Amsoil cetane booster and found a manufacturer of B100 about a mile from my girls house.

Time to break out my DDD head and find a ST45. I have some KL200 oil. As soon as I get the B100 I'll see if the KL200 will mix with it. I also have some Klotz model lube for gas engines to see if it will mix. It is supposed to be clean burning. I can set up the Super Tigre on regular ether fuel, try the B100 and oil and then B100, oil and cetane. Biodiesel may need preheat of the fuel and better atomization.

For some interesting engine and fuel atomization ideas check out this site http://www.rexresearch.com/index.htm

I was introduced to the Babington principal many years ago. Using it you can atomize #2 fuel oil to a fine fog and it will burn as clean as natural gas.

Kelly,

The owner of DStar was quite evasive but I don't blame him. This IS, after all, real serious stuff for these guys. He seemed to be the same kind of guy we ALL are, just a happy bunch of nuts who love small machinery. But he had a company to run involved in some hi-tech security issues. So be it, I contributed what I could, specifically, he appreciated my input on the superiority, IMO, of Cox props. Apparently, prop design, in very small sizes is unknown to aeronautical engineers.

Regarding the flat disc. I'm also thinking that an insulated disc of some sort may be an advantage. One way to do this would be to make up a pile of very thin, copper discs and stack them. The air trapped between the layers would act as insulation. A neat approach to retaining heat in a hot spot of sorts.

About carbon. My test flyer with the dieselized .074 was not up to snuff lately so I took the head off for the first time this summer. This head has seen all manner of fuels with all manner of oils. Holy Smokes, Batman, carbon thick enough to scrape off with a knife blade. The head was dark, but not bad. The piston was crudded up some badly. It was soft crud but crud nonetheless.

Yes, WFO is very doable with a no ether fuel. Starting is the issue and ether is an essential for hand starting.

Greg,

I'm pleased to hear that 4 strokes respond well to a no ether fuel. Can we assume you're using Benol and Amsoil? Starting may be eased by using a special prime mix of 80% ether and 20% oil.

Skypilot,

Glad to see another diesel dude having fun experimenting. Thanks for the link.

OK.

Went to the local Canadian Tire to pick up some Amsoil, 2 cycle oil. Couldn't find any because, in that section, all they had was this "hp injector" stuff. But wait, the fine print says that it's a Synthetic, 2-cycle oil. Amsoil, ya gotta re-label the stuff. Anyway, the label also says that it's recommended for " TC-W3 and API-TC applications as injector oil OR as 50:1 pre-mix".

Here's the issue though. The viscosity is nowhere near castor or 50 Avoil. More like 20 or so. Gonna have to call Amsoil tomorrow.

But, also at Canadian Tire is this " Diesel Fuel Supplement" from a company called "Power Services". Big letters says "Cetane Boost" . This is made up of "petroleum distillates and 2-ethylhexyl nitrate." The issue is that a 32 ounce bottle is good for 50 gallons for a cetane boost of 4. Amsoil Cetane Booster, on the other hand, indicates a cetane boost of at least 4 for a 16 ounce bottle to 100 gallons. That means that you may need four times as much of the Power Services stuff as Amsoil. However, if this works, along with the Amsoil 2 stroke oil, those of us north of the 49th may be able to get ALL of our ingredients locally. Neat.

On another thread, I showed how turbo plug adaptors can be made to suit Norvel, Cox and other small engines. Another solution to the shortage of Norvel and Cox plugs is to just dieselize the little stinkers. Working on that just now, making diesel heads for the TD .010 and the TD .020. Yes, the cranks may be an issue but I've got plenty of spares. Fun to try anyway.