greg,
look further. in that paper they say they had the most troubles for wear in the (piston ) pumps due to the reduced viscosity in respect of diesel fuel.
As for glow engines...did you note the BOILING temperature of methilic alchool?...it is 149°F. Did you ever see a crankase working UNDER that temperature?.... And Kerosene boiling point is from 347 to 664°F, did you ever see a crankase going UP to these temperatures?
As for the viscosity reduction by eliminating ether, I guess it becomes 1/4 of the original oil. THE excessive diluition of oil in the crankase requires to be somewhat compensated by increasing the oil percentage.. ..furthermore the diluition could explain also why diesels seem so oil thirsty.... and what you subtract from one side has to be added to the other one.
Last but not least, what has necessarily to do the evaporation in the cranckase with the combustion in the cylinder.? Every commercial diesel has LIQUID fuel injected in its cylinder, and they seem to burn it rather satisfactorily (cetane allowing)!
As for controlling the wear to the conrod, I think useful to make a metal rod with a very faible conicity, say 1/50" each inch. Minimum diameter that one of a (new) rod end hole. When conrod wears it will go inner in the hole, giving the exact measure of the wear.
ugo

PLS CORRECT
.....When conrod wears, ITS HOLE will go inner in the ROD, giving the exact measure of the wear.
UGO

Are you saying that kerosene is not evaporating at all prior to the combustion chamber? It is hard to start an engine cold on etherless fuel. I think this indicates that atomization of the carb is not the only factor in burning the kerosene. In the four stroke engines it is quite obvious that the intake tube is operating at maybe 30-40F below ambient while running glow fuel, and while on diesel above ambient temperatures, but somewhat less than the head it is mounted to. D-star has a curious looking carb, I think I read they are doing something special to atomize fuel in the carb.

If the viscosity of the oil mix is only 25% of the original castor oil, how do we know that this isn't actually enough? Many people say that model engine are substantially over lubricated. http://www.klotzlube.com/tech/KL-198.pdf this is a model oriented synthetic lubricant that is SAE 5 rated for model engines at the percentages we use.
http://www.klotzlube.com/tech/BC-175-1.pdf This SAE 50 castor oil product the same comapny sells is recommended for model glow engines at 3-5%!! Nobody I know does this, but they are well known in the lube industry, and I don't think they made a mistake. Why wouldn't 20% even if it's diluted, be suitable to prevent failure?

Ugo, do you have experience with model engines failing with this sort of fuel mix? If so I'd like to hear what happened so I can look for similar problems.

Oil thirsty, compared to what, and how do you define it?

Merugo,

I gave my 10% ether fuel mix ingredients as

To make 1 litre of fuel with a 10% ether content ...

2.5% ignition improver 25mls
12.5% Synthetic engine oil 125mls
16% modified olive oil 160mls
10% ether 100mls
8% castor oil 80mls
kerosene 357mls

*******
(extra kerosene is incorporated through diluting the 30% commercial fuel mix and this brings the total kerosene content to around 51%)
*******
The quantities shown add up to 847 mls which is apparently some way short of 1 litre !

I should have pointed out that there is actually more kerosene in the mix than those figures show.

There is a further 153mls of kerosene in the mix which is there as a result of diluting the 30% commercial ether, 24% castor oil, 2.5% IPN and the balance being kerosene in the 1 gallon can.

Sorry for any confusion, but I overlooked the fact that the extra kerosene was coming into the mix as a result of diluting the commercial fuel..... of course I know this but it is not apparent to anyone adding up my fuel ingredients !

I have added this information to the ingredients shown in this post.

The semi synthetic car engine oil is a 10w40 oil produced in the UK by Millers oils and is specifically for diesel engined cars and those using turbos also.

The ignition improver is a diesel fuel additive for cars and is also made by Millers Oils. The ingredient of use to me is 2-ethylhexyl-nitrate. PAW (the UK model diesel engine manufacturer) advise that 2-ethylhexyl-nitrate can be used as a direct substitute for IPN which is becoming harder to obtain.

The test weather conditions varied considerably. Testing was done over a period of time and conditions ranged from very hot, sunny and dry,temp around 26C to cold, damp and windy with temp around 6 to 8 C.

Engines were PAW diesels some with control line carbs and others with RC carbs.

The oil content of this fuel mix is high at around 36% and I intend to work this down to 30% and possibly 25% . I will initially drop the olive oil to 10 % and see what happens.

I am quite happy to run a reasonably high oil content 25% to 30% as long as it enables good and consistent running... the higher oil content serves to reduce the total amount of kerosene in the mix and this helps in keeping engine temperature lower, not as low as when there is more ether in the fuel but still acceptable to me.

Greg mentioned that one thing that hasn't cropped up in discussion is what benefit do we gain from increased kerosene levels ?

I haven't really got any figure around this yet but hope to get some idea when the weather is good for flying again. I did several flights with a 15% ether mix and this looked pretty good.

The plane was a 100 inch wingspan glider. The engine was a PAW 09 (1.49) with a straight venturi - no RC carb so that the engine was running flat out all the time.

A 2 oz tank of the 15% ether mix was giving me 23 minutes running time. If the engine could have been throttled back after gaining sufficient altitude then I would probably have got fed up before the fuel ran out !

As Greg stated - the initial purpose of the thread was to reduce, or eliminate ether in the fuel mix.

Here in the UK model diesel fuel is only available in 1 litre cans, bigger amounts have to be got by mail order.

A gallon of 30% ether mix costs £30 which is approx $56 US and a further £6 or $11 for delivery

Reducing the need for ether or eliminating it entirely makes the use of model diesel engines much more attractive.

It has been mentioned that olive oil is not cheap.

In the UK a good olive oil is about £5 to £ 7 a litre .... $9 to $13
Castor oil is £8 which comes to $15 !

By comparison olive oil is cheaper than castor and is used at lower percentages.
The semi synthetic oil I also use costs approx £3 or $6 a litre.
Using a combination of semi synthetic and modified olive oil is still cheaper than using the castor oil which is normally found in commercial model fuel mixes.

Reg

As kerosene is the least expensive ingredient the cost is reduced by increasing the percentage. Kerosene also has the highest BTU content it also improves fuel economy of the mixture.

greg,
take a look at this....Chapter 10 - The Infamous "No Oil" Demo
At at least three major motorcycle rallies this past year, we have witnessed live demonstrations put on to demonstrate the effectiveness of certain oil additives. The demonstrators would have a bench-mounted engine which they would fill with oil and a prescribed dose of their "miracle additive." After running the engine for a while they would stop it, drain out the oil and start it up again. Instant magic! The engine would run perfectly well for hours on end, seemingly proving the effectiveness of the additive which had supposedly "coated" the inside of the engine so well it didn't even need the oil to run. In one case, we saw this done with an actual motorcycle, which would be rid den around the parking lot after having its oil drained. A pretty convincing demonstration - until you know the facts.
Since some of these demonstrations were conducted using Briggs and Stratton engines, the Briggs and Stratton Company itself decided to run a similar, but somewhat more scientific, experiment. Taking two brand-new, identical engines straight off their assembly line, they set them up for bench-testing. The only difference was that one had the special additive included with its oil and the other did not. Both were operated for 20 hours before being shut down and having the oil drained from them. Then both were started up again and allowed to run for another 20 straight hours. Neither engine seemed to have any problem performing this "minor miracle."
After the second 20-hour run, both engines were completely torn down and inspected by the company's engineers. What they found was that both engines suffered from scored crankpin bearings, but the engine treated with the additive also suffered from heavy cylinder bore damage that was not evident on the untreated engine.

SO AFTER ETHERLESS FUEL ONE CAN RUN ON OILLESS FUEL! WHEN ONE WILL RUN ON FUELESS FUEL?
Now to you. Someone says This lube ON GLOW mix is sufficient at 5%, well ,nothing strange since 5% lube on glow means 20%% lube ON DIESEL. WHY? because of DILUITION. Methanol is evaporating since from the drizzle, and its LOW boiling point minimizes its presence in liquid phase in the krankase . If 80%of fuel evaporates the oil is 75%diluted.
Now to the unfortunate kerosene drinking diesel. Ether evaporates totally since from a carburator. ( I remember one day of my first happy diesels I bought some ether far from home. It was an hot summer and the cork was not so good, so I looked my precious liquid disappear little by little leaving a thin layer of frost on the cork!!)This lowers the temperature of the unfortunate kerosene: What you suppose "vaporizing" in the carburator, goes indeed further deep in liquid phase. IT FOLLOWS that FOR OBTAINING THE SAME VISCOSITY THAN IN THE GLOW CASE YOU MUST USE A MIX 20% ether, 60% kerosene...AND 20% OIL!!!
This means oil thirsty for diesel...and..if you give away the ether in your mix, leaving straght kerosene, STRANGE AS IT CAN SEEM, you have to INCREASE the percentage of oil to 25% for obtaining the same operating viscosity.... this means that ether mixes have an HIGHER WORKING VISCOSITY!!
slope soarer,
thanks, this mistake is ever more convincing me of the need of some "template" or standard form for collecting mix formulas and data proposed here!
ugo

So, the real question that I posted several pages back has surfaced.

How much oil do our engines really need?

Why does a diesel seem so oil thirsty?

Have we considered air to fuel ratio? Or in this case air to oil ratio? Glow engines pump 2 times the oil per stroke simply due to air fuel ratio. This means that every kilo of air gets 133g of methanol and 33g of oil when 80/20 fuel is used, at 6:1 stoich ratio. Diesel, on the other hand, runs almost half the mass of fuel of about 12:1 stoich ratio, so a kilo of air gets 66g of fuel and 17g of oil for a 20% oil fuel mix. In this regard diesel needs much more oil in the mixture.

Does this have any weight in the diesel needs more oil argument? I think it explains it COMPLETELY.

Greg,
sorry but this DOES NOT EXPLAIN ANYTHING about ther need of oil! A turbine works at stoichometer value and runs on NO oil in the fuel! Do you know that someone is adding any significant oil in a gasoline if he has a four cycles engine, do you think anyone adding oil in industrial two stroke engines fuel? so your reasoning is suggestive but does not hold . The reasons of the high oil percentage in a well designed and mantained engine is ONLY ONE D I L U I T I O N!!!!!!. since the straight oil needed for an ENTIRE 20 min engine run DOES NOT EXCEED THE WEIGHT OF 1(one) gram!!! ( this explains why you can run on gasoline for 20 ours WITHOUT oil). If you dilute and want to lubrificate the remedy is: ADD OIL in order to have sufficient viscosity.
ugo

Ugo,

I don't get it. Please explain to me mathematically how my above response is incorrect. The oil is along for the ride with the fuel in this case. If less fuel mixture is going through the engine, this means less oil is going through the engine. Remember we are mixing oil with our fuel. So oil consumption is proportional to fuel consumption. We are dealing with total loss lubrication systems. If a diesel needs less fuel mixture, diesel fuel must have more oil to consume the same volume of oil.

Please understand we are talking MODEL AIRPLANE ENGINES. Every single model airplane engine I have seen uses lubricant in the fuel. So, yes we are mixing oil in the fuel, ALWAYS, two stroke or four stroke, diesel glow, or gasoline.


Theoretically what you are saying is absolutley true. Please show some kind of evindence of this in practice. The presence of ether in our model engines isn't a lubrication issue. Ether is present for ease of starting and handling.

And the one question that will answer all of our questions.

How much oil and what viscosity does a model engine really need?

If you don't have the answer to this question I don't think you can definitely say that ethereless fuel will damage an engine. We have to have a known to answer an unknown. Unless, of course, you have done experiments of your own.

You seem to fascinated with dilution. Thank you, for bringing it up. If it was a real problem those of us running fuel without ether would surely have noticed some problems.

Greg
every mechanical moving coupling needs some lubrication . Steresses and motions differ for each part and for each moment. So if you use a SINGLE OIL for lubrification you have to compromise.Worse, temperatures are different coupling for coupling.
If we deal with not extremely fit MOVING parts, 5-15 centistokes are a limit value that allows for making joints not mechanically and dimensionally constrained by viscosity, but only from structural needs.
It is obvious that every mechanical maker prefers not to waste material for allowing the use of low viscosity lubricants, unless constrained to. Model engines makers do not escape from this rule. Ordinary materials are used, in order to make engines reasonably cheap ( do not mention D-STAR, pls!) .
Pls note here I am speaking of plain lubrication, not of boundary lubrication since this interests zones and moments out of my rough knowledge.
In internal parts, where temperature does not exceed 100°C, the viscosity values needed are ordinarily obtained by straight oils sae 20-30. This level of WORKING viscosity is easily obtained in any two strokes gasoline engine where fuel EVAPORATES ENTIRELY after a few seconds run. This NEVER happens in model engines, so the poor lubricant has to work in diluted form.
Model engine mechanical couplings do NOT escape friction laws, and ordinary remedy to them, that is oil lubrication. BUT UNFORTUNATELY THE OIL RUNNING IN A MODEL ENGINE crankase is diluted OUT OF ANY USUAL TERM, lowering considerably the USEFUL viscosity .
In order to keep viscosity reasonable one has to rise the percentage of oil in fuel and its viscosity.
Now remember, DIESELS WORK WITH KEROSENE, that DOES NOT EVAPORATE AT ALL IN THE ENTIRE CRANKASE, (notwithstanding your hopes!) since a mere fraction of it, BY SURE less than 10%, is allowed to evaporate WITHIN the crankase in one turn and UNDER 200°C. This leads to an higher need of lubricant in the mix.
Ugo

ugo, what your saying is true , BUT , its not all the story re lubrication.
A lubricants ability to do its job is also effected by its molecular size-this doesnt change with dilution, and its molecular polarity which effects its ability to adhere to metal surfaces- this is were vegitable oils in particular reign supreme over other oil types- vegi oil molecules tend to stand vetical from metal surfaces whilst being electrostaticaly adhered wereas other oils tend to just lay about as a jumbled mass and are more easily wiped off the surface.
this tends to make vegi oils -castor/modded olive oil , act independent of dilution factors moreso than mineral/synthetic oils.
Stewart

Hi Greg,
You stated....

As kerosene is the least expensive ingredient the cost is reduced by increasing the percentage. Kerosene also has the highest BTU content it also improves fuel economy of the mixture.

Greg

This comment was in regard to modified olive oil combined with synthetic oil to give the lubricant in the fuel still being cheaper than castor oil.

True, kerosene is cheaper than either olive oil/synthetic blend or even straight castor oil but it comes at a price. I found - just as you would expect - that increasing the percentage of kerosene in the fuel mix also causes the engine to run hotter. Totally to be expected as the fuel contains more "energy" and will give better performance/longer run time.

My goal is not to set new records for speed or flight times per ounce of fuel. I want to use a fuel that is more economical than that sold and also have the engine run at what I think is a suitable temperature. Running with high ether content fuel reduces the engine operating temperature... especially the crankcase as the ether content is reduced so the crankcase temperature increases accordingly. Running a high % of lubricating oil helps keep the engine temperature within a range that I am happy with. I could reduce oil content, save pennies, have longer run times but would be concerned about engine longevity.... I prefer to keep peace of mind

Merugo has raised a point that I hadn't really thought about....

Why is crankcase temperature so noticeably cooler when using a high percentage of ether in the fuel ?
Because the ether is evaporating and this evaporation keeps the crankcase much cooler.

What happens when ether is reduced and kerosene is increased ?
Performance gains are to be had but.... crankcase temperature considerably increases in line with the increase in kerosene.

What I see happening here is... using a high ether content fuel a certain amount of the ether evaporates - hence the crankcase cooling - and as a consequence of this the oil is now less diluted than when the fuel was first mixed and also just prior to it entering the engine..... the ether has reduced therefore dilution is less of the remaining fuel charge.... in effect the oil has now become more viscous.

Looked at this way then a mix containing 30% ether and 25 % lubricating oil is going to give more lubrication in the engine than a fuel mix which has no ether content and 25% lubricating oil.

A non-ether fuel should have more lubricating oil in it than one with a high ether content.

How far can we reduce the oil content..... well how long is a piece of string ? Engines vary, materials and tolerances are different. I run 2 stroke diesels, you run 4 stroke. I want to err on the side of caution... you may be more adventurous [X(]

If we want to reduce oil content significantly then I think Andy is on the right track with his ideas for fitting small roller bearings to the con rod, especially at the wrist (gudgeon) pin end.

Reg

Ether are not a lubricant, the ether are destilated of alcohol and sulphuric acid and has a ignition temperature at 180-188 degree celsius and cetane number at 80-90 therefore ether will ignite easier in low compression mean ease of starting and handling.

Jens Eirik

Thank you for that explanation. I see what you are saying. The four stroke is a little different in that the fuel isn't pumped directly through the crankcase. Surely the piston ring and liner of the four stroke is experiencing the worst case lubrication. In this case the best thing I can do is use a crankcase lube system for the four stroke.

Here is what I'm saying. If a glow engine burns a a liter of fuel with 18% oil in one hour, and a diesel burns half a liter but with 36% of oil, both engines have seen the same total volume of oil. If the diesel's lubricant is diluted, it is in a significantly worse situation even if there is more oil in the fuel mix, no?

Let's look at it differently. Do we know how much oil is in the two stroke engine after a certain period of time? In a two stroke engine (and model four stroke) all of the oil is continually replaced. When is equlibrium reached? Certainly we could put a drop of oil into the crankcase and run fuel without oil and the engine would run for a period of time before wear became a problem. We don't know how long that is. Even an engine running on a gaseous fuel like propane would eventually fail.

Only testing will prove if the 20% lube in my fuel is enough.

Obviously the lubrication issue does need more research and testing.

Reg,

I agree with everything you said. In four stroke engines however the head temperature is at least 100F cooler running as a diesel on etherless fuel than glow. I didn't really check crankcase temperature. The eliminated ether must be replaced with something and the logical answer is kerosene. More testing may result in adding oil to the mix as Ugo has brought to our attention.

I am a bit more adventurous. Being on the safe side won't answer the question: How much oil is really enough? Since castor oil costs 10-20 times that of kerosene, knowing how much oil is necessary will have an impact on the fuel cost. I don't want to wear engines either, fourstrokes are exactly disposable engines.

Friends,
now the discussion is opening a new front, but to be clear a mix is a mix and every components ha to match the others. Combustible, lube and improver ( today I suggest to include ether in this cathegory) must match somewhat each other. The blanket is short, so. every component is affected by others. Discussion as fairly open.
I propose to use a template as below for discussing and possibly compare mix proposals and references. This thread is so long that something useful can be lost or inadvertidely repeated if not properly resumed. Reference over wich to discuss may be useful both to participants and viewerrs. I hope you will adhere by filling the form with the mixes you have already formulated and/or tested.

Suggested mix report scheme

--------------------------------------------------------------------------------------------------------------------------------------------------
MIX NUMBER: SUGGESTED NAME:: DATE:


ORIGINAL REPORTER: LAST EDITOR: LAST EDIT:

OTHER USERS:

FORMULA (in order of decreasing percentage of volume ):
1) %
2) %
3) %
4) %
.....
The way the mix it was obtained:



1)ENGINE: CARBURETOR: RUN TIME: STARTING: USER:
Comments:

2)ENGINE: CARBURETOR: RUN TIME: STARTING: USER:
Comments:

Additional user obsevations:
Nickname : Observation:
Nickname : Observation:

Non user comments:
Nickname : Comment:
Nickname : Comment:

PURPOSE:
SHARE FORMULAS, EXPERIENCES AND SUGGESTIONS.
RULES:
EVERYONE CAN ADD HIS EXPERIENCE AND/OR BRIEF COMMENT FOR A GIVEN FORMULA by reediting and setting edition date
USE:
COPY; EDIT AND PUBLISH. NO CONTRIBUTION CAN BE MODIFIED IF NOT BY ITS AUTHOR
END
---------------------------------------------------------------------------------------------------------------------------------------------------

Who wants to start wth the mix No 01 ? Thanks
Ugo

the form went a bit altered . spaces after some indications went lost in publishing. My fault not to have done a preview, but the template can obviously be used by inserting your data after the headlines. ugo

4 stoke or 2 stoke - I doubt it makes much difference. The oil that comes out the tail pipe of my OS 40 LA is nice and thick and black. In fact I beileve that that is the kind of oil that you would find in the 4 stroke because it can only get oil left over from combustion and on my mix that is nice thick oil.

I've been flying my mix a bunch the last couple of weeks. I put a 13x5 prop on this little engine and it pulled it great. I finally crashed yesterday so now I will have to dissasemble the engine to clean it.

Treven.

Slope soarer,
thanks for your contribute. If you add 153ml of commercial mix 30% eth 24% cast 46%kero you add 46ml eth ,37 cast, 70 kero to your other components, as I have reported as your results in my proposed form. If you want you may vary it, editing as needed since it is really yours. but please mantain the outline of the form , it is intended to be used also by others.
To others,
pls why not to resume your formulas in this proposed form? It will take a few minutes and your experiences will not be disperded!
Thanks,
Ugo
---------------------------------------------------------------------------------------------------------------------------------------------------
MIX NUMBER: 01............................................SUGG ESTED NAME: SLOPER's.................DATE: 01/04/07

ORIGINAL REPORTER: SLOPE- SOARER.............LAST EDITOR: MERUGO........................ LAST EDIT:01/09/2007

ADDITIONAL USERS:............................................ ..

FORMULA (in order of decreasing percentage of volume ):
1)-43 % kerosene
2)-16 % modified olive oil
3)-14.5% ether
4)-12.5 % synthetic 10w40 Millers diesel oil
5)-11.5 %castor oil
6)-2.5 % EHN from ignition improver by Millers

The way the mix it was obtained: by mixing components with 15.3% of commercial fuel

ENGINES
1)PAW.2.49..CARBURETOR: RC .. RUN TIME: ...........STARTING: electric/primer USER:slope-soarer
Comments:used in 5-25°C range. worked well. 20' running times. throttle very good

2)PAW.1.49.CARBURETOR: fixed...RUN TIME: ...........STARTING:........................ USER:slope soarer
Comments:used in 5-25°C range. worked well. 20' running times
.................................................. .................................................. .............................................
Additional users:
Nickname :........................ Observation:
Nickname :........................ Observation:

Non user comments:
Nickname : merugo ...Comment: relatively high ether content. total oil seems too much
Nickname :................. Comment:

PURPOSE:
SHARE FORMULAS, EXPERIENCES AND SUGGESTIONS.
RULES:
EVERYONE CAN ADD HIS EXPERIENCE/ENGINE AND/OR BRIEF COMMENT FOR A GIVEN FORMULA by reediting and setting edition date
USE:
COPY; EDIT AND PUBLISH. NO CONTRIBUTION CAN BE MODIFIED IF NOT BY ITS AUTHOR
END
--------------------------------------------------------------------------------------------------------------------------------------------------

merugo,

I like your idea and I will post my mix on your new thread. Why don't you start it?

Treven.

Treven
thanks for your reply and suggestion. An extremely concise thread could go well. Maybe starting simply with the blank form followed by those filled and/or edited by each participant. Let's try, but in respect of slope-soarer I would like his authorization for publishing his mix at first. If he don't reply we can start with your mix as No01. He could add his when he wants.I will start by publishing the form and you follow with your mix assuming No1 . Pls wait until tomorrow. What a name " Every diesel mix"? ?
Comments welcomed
Ugo

Merugo,

Your listing of my fuel mix needs a slight alteration.....

castor oil is 8% (not 11.5%)

ether is 10% (not 14.5%)

If you like you can put in the "suggested name" slopers 10% ether mix.

Go ahead and use it.... Trevans should be an easier mix to write out

Treven,
Great to see you still having so much cheap fun. I would like to join in but it has hardly stopped raining since October, even if it's not actually raining everywhere is soaking wet []

Pity about the crash... still a good chance to strip down and examine the engine's innards.
Any decent gunge you scrape out of there could probably go straight back on the road surface

Reg

Merugo,

How about........ Alternative model diesel fuels as the name of the new thread ?

We could do with something that would be picked up by a search engine if someone is looking for information and doesn't know about this group.

Reg

Slope soarer,
thanks for your authorization. Of course starting using a new form may be useful, since it can easily correct misunderstandings, but when beginning some mess may happen.
You said to have added 153 ml of commercial mix to the 847 ml mix you prepare with your listed components. You have as result 1000ml of mix. But by adding the 153 ml of commercial fuel you have effectively added some ether, some castor and some kerosene to your components. So you have to add their volumes to those you put separately in your mix. The percentages ( or as you prefer, the ml each 100ml) that follow should be those I have reported. Maybe I have messed something, but I don' t find what, so please control. It should take a bit of patience, but I think it will reward.
Ugo