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Right fuel for a "new" old Enya


David Ovenden
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2 hours ago, Paul De Tourtoulon said:

Oh dear am I the only one still adding caster ( 1°/2° ) oil in my engines, 2 strokes, 4 strokes even a Laser ?, and my helicopter engines and at 35°c on the model field,,,

 

 

 So do you want some Caster oil David ?,,,?

 

That; void your warranty ?

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My 75, very early version, 30 ish years old, with a short silencer, was happy, or at least burbles as ever, yesterday, 7 % oil, no caster.

 

temperature in the shade, 34° C.


More than I was happy. 

 

stick caster in the bike motor if you like the smell. Don’t screw the throttle.

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13 hours ago, Paul De Tourtoulon said:

So my 20 year old Laser is not guaranteed any more,,,?

 

Nope, sorry ?

 

And Nightflyer...duraglo..GN/X5, dynaglow... Its like you are listing my nightmare fuels. They are all utterly awful and you might as well dip your engines in tar ? 

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Frank, the bracket you need is fairly stiff, so that the screws are pulling tangentially to the faces on it that they bear against.  Two layers of Jubilee clip steel would probably work, maybe even epoxy them together for extra stiffness.

This advert for an Enya 29 to 45 exhaust clamp shows the plan view of what you need to make, to ensure it presses on the right part of the crankcase.

Enya Exhaust Clamp

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What everybody seems to be forgetting is that this Enya 15 is a plain bearing engine. The crankshaft is running in a bronze bush, not ball bearings. It does need more oil than a modern design. I also find that the small end bearings on these old Enyas can wear, so some decent oil content would help there too.

 

Back in the 80's I ruined a couple of engines like this by running them on the new low oil synthetic oil fuels. That fuel was perfect in my ball bearing ABC Super Tigre, so I did not anticipate the wear that would take place in old plain bearing, iron piston types. I really would recommend going for something with around 20% oil and including some proportion of castor. People can grumble about how much mess it will make, but this is only a 2.5cc engine. It's not going to be chucking out a huge volume of exhaust, so what harm is a little extra oil "goo" going to do?

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Forgot to say, but if this really is a new engine, never previously run, it is going to need running in. It's all very well to run in your modern Laser engine by simply flying it as normal. Back in the 70's, 80's, Enya were well known for their iron piston engines having a very close piston/liner fit which did need some careful running in. You don't want to be running it in on marginal oil content. Better safe than sorry!

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On what basis do you recommend the extra oil? Engineering knowledge, rule of thumb, because its what we have always done? My OS15fp is plain bearing and it ran better than ever on 15% oil. Also, every glow engine on the planet has plain bearings in their conrods and its this which is the usual limiting factor for lubrication. I dont recall anyone seizing a crank bush but i have seen plenty of conrod bushes go. I also running my OS FF240 on 15% synthetic and it called for 20% castor at the time. 

 

Running the engine in will need a little more care than a modern Laser. But, you dont want to be running slobbering rich for a month either as that wont do it any favours. I posted a link to a good procedure earlier in the thread. And again, if i hear another story of 'back in the day synthetic ruined my engine, castor is life' etc i am likely to loose the plot. The 1980's was a long time ago, oil is different now. Even the same oil is better than it was then and certainly i would take a modern synthetic over bean juice at this point. 

 

As a final point, i wish people would stop scaremongering when it comes to engines. Yes, its possible to damage them by doing the wrong thing but its very unlikely you will flat out kill in one session unless you fill it with sand. If you lean it off too much or overheat it, yea it might stop but i wont be dead. Continued toasting will damage it, but one hot run wont be an issue. In fact a leccy motor, ESC or lipo are far more likely to suffer a permanent failure involving the dreaded magic smoke if they are cooked in a similar fashion. 

 

If you took this little enya and ran it flat out on 5% oil from new it is very unlikely it will die. Is it recommended? no, but its not likely to seize solid and kill itself. Running the 5% nitro 15% synth oil discussed here, and running at around 90% of peak tune on a light load prop for the first handful of 5 minute runs will be just fine. Once its had a bit of that tune it up, get it in the air and just go a little easy. Dont thrash it completely flat out, dont use an 8 foot prop. Just use some common sense and stop worrying about it. 

 

 

 

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 As noted on the first page of this thread my NIB old Enya 15 has been running just as Jon recommends above with no issues.

  An old friend who fly's only control line diesel will only use D1000 with 28% castor ! He ran out the other day but would not have any of my D2000 [still 24%] in his engine's, but there you are. My older engines. Mills, DC, Frog are well happy on it. I am sure my PAW's would be happy on less oil.

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I have to say Jon that your posting does come across as a little aggressive, or perhaps exasperated, but that's probably just the way things seem sometimes without a direct 2-way conversation. We all have different experiences in life and thereby end up forming different opinions. It does not do to talk people down without prior knowledge.

 

In my life I have done  a lot of rebuilding of car, motorbike and model engines. The bike engines were thrashed around 6 or 8 hour endurance races and I never had one spew its guts. Perhaps that was just luck! Also I did work in motorsports engineering for a short while, but nowadays I earn more by drilling big holes for global warming juice, sadly.

 

If you look back at the engine test reviews of the period, they were actually running (or at least running in) these kinds of engines on 25% castor! I'm not suggesting that and yes, oils have improved. My comments are based on having stripped and rebuilt a lot of old Enyas and the most common things I see are worn out little ends and excessive float on the cranks. I can't speak for an OS 15FP, but that's a different (if similar) engine.

 

Also, if you consider PAW diesels, for the plain bearing engines the manufacturer currently states 30% castor for running in and 25% thereafter (yes, probably overly safe!). Less oil is recommended for the BB engines. I know, a different engine again, with higher compression loads, but it reflects my view that more oil is wise for a plain bearing engine.

 

A plain bearing needs more oil than a BB. A plain iron piston needs more oil than a ringed piston. Therefore it strikes me that an engine with a greater proportion of plain bearing surfaces is going to need more of an oil overhead than a BB/ringed engine.

 

Maybe the 15% oil will be perfectly OK (as per JD8 above), but why not play safe? Perhaps our fellow modeller will accidentally give it a lean run when it has not yet run in properly. Or maybe he will like this engine so much that he flies it every weekend and then it wears out. Try getting spare parts for your Enya. SWM seem to have very little stock these days. I have to go through the faff of dealing with the US Enya agent. So my suggestion of 20% oil is based on playing safe for very little extra goo on the model. And a few % castor within that 20% does smell nice ?

 

Anyway, Jon, why not go outside, take a deep breath and look up far into the sky for a few minutes? It will help!

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The reason i get frustrated is because the same old nonsense gets spread around year after a year. Most of it has always been wrong, but its crept into modelling folklore and is simply repeated over and over again without any critical assessment or any real understanding of what is going on. So before i go outside we need to correct a few things. 

 

The misconception about oil is how the amount you have somehow impacts the wear you get. More oil means less wear and so on. That is not actually true however and you either have enough oil, or you dont. If you dont it will fail more or less immediately. This notion of wear over time is wrong and the quality of the oil is far more important than the quantity. 5% synthetic will be a good deal better than 30% beef dripping. And you keep saying play it safe, play what safe? 15% synthetic oil is more than enough, you cannot get any safer. 

 

Another one for the folklore book is this almost mythical 'lean run'. You cant run it lean, it will overheat and stop in very short order or it may kick and throw the prop. No damage will be done unless you repeat this roasting over and over again. As i mentioned before, one lean cut wont kill it.

 

Little end failure. There is very little rotation in a little end as they just rock back and forward. The thing that busts them is excessive load. This can be due to high rpm, or high physical load with a huge prop. Given the nature of their loading, they are not as fussed about lubrication as a big end with rotation to deal with. This is why big end failure is not uncommon but little end failure is. 

 

Crank end float...its a plain bearing, that is what they do. You need to build float into the design to stop the thing pinching the crankcase. 

 

PAW engines use plain aluminium for their crank bearings. The crankshaft runs directly in the ali case with nothing else going on. Ali is not as good a bearing material as bronze, so more oil may be advisable. Saito have the same situation as they do not use bronze bushes in their conrods. Also, if my PAW's are anything to go by there is no oilway cut in the bush. Enya's i have seen, and OS as well have an oilway cut into the bush to allow better distribution of the oil. Cant say for sure if it is the case here but its likely. All of that said, my PAW 149 has run using 20% since i got it when i was 14. Why not 30%? because i was 14 and didnt read instructions. I just went to wings and wheels and bought a tin of diesel. It was not until a few years ago i actually read the tins and saw it was 20%. Nothing has blown up yet and there is no wear in the engines. 

 

Im not trying to put people down, but at the same time so much of the information being banded around is completely wrong and its just misleading people. That is all i am trying to stop. Misinformation, however well meaning, is still misleading. 

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Aye Jon, we could go on. I think we need a Youtube "Hiltler Rant" on model engine oil!

 

Excessive crank float = +1mm say and the big end bumping into the back plate. Give me some credit!! The PAWs are favourite for that too. Ends up with a thrust washer.

 

On the endurance engines (Honda 600), the little end was an immediate weak point, so we had to bronze bush them and make some oil ways which Honda had not. That was rectifying insufficient lubrication and poor bearing material.

 

The only big end failures I've seen in Enyas are from helicopter use - sustained high rpm. Otherwise it's commonly little ends in all the smaller sized iron piston engines. Judging also by the charring sometimes under the piston crown and even on top of the rod, these little end problems could be a symptom of over-heating, which you might compensate by having some more oil and avoiding lean runs.

 

There is a spectrum of:

Not enough lubrication = immediate failure.

Marginal lubrication  = accelerated longer term wear

Sufficient lubrication = OK

Excessive lubrication = loss of power due to drag and poor combustion (and an oily model)

 

Then it's a case of making a judgement on your oil content. For me, a hot tuned  2.5 litre VVT Duratec engine is in my garage begging for some attention to its exhaust, so I wish David all success with his classic little Enya, whatever fuel he ends up using.

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Well I think this topic has run now its course! It would be a shame if the thread ends up falling into the old elephant trap of  "castor vs synthetic". I have made my decision and just need to get on with running the engine. Thanks for your all thoughts and ideas. I will report back once the engine has been run a bit. 

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.

“There is a spectrum of:

Not enough lubrication = immediate failure.

Marginal lubrication  = accelerated longer term wear

Sufficient lubrication = OK

Excessive lubrication = loss of power due to drag and poor combustion (and an oily model)”

 

An old myth. Excessive lubrication is a killer of engines. They run hot as explained, and unless the oil can handle the ( non designed for) heat, a bit of metal melts. 
Outboard motor people are rich from users shoving a bit more oil in for luck.

 

Between marginal and sufficient there is a huge number of hours running.

And I don’t reckon many model’s we use, not hitting the ground, find out what division they are in. 
 

Sorry for the aggression, but this is old hat. Sorry your  exhaust is knackered.

 

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5 hours ago, Jonathan W said:

 

 

The only big end failures I've seen in Enyas are from helicopter use - sustained high rpm. Otherwise it's commonly little ends in all the smaller sized iron piston engines. Judging also by the charring sometimes under the piston crown and even on top of the rod, these little end problems could be a symptom of over-heating, which you might compensate by having some more oil and avoiding lean runs.

 

 

As before, you cant run an engine lean. If its too lean combustion cannot be sustained and it stops. 

 

If an engine is overheated, adding oil will not prevent damage.

 

I am pretty sure you also just made my point for me on little end failures as the high rpm imposes a high load. More oil cant fix that.  

 

The conversation is pointless unless you accept some of these fundamental principals and stop repeating modelling folklore like its a fact. 

 

David, glad you found the answer to your problem. 

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Jon, you are seizing on some things I have said out of context while ignoring other things and therefore "jumping to conclusions". It's not worth the effort, we should just skip it. As per my previous post, I'm done with this one.

 

Actually, I'm in shock that Don Fry's X-ray vision has declared my Ginetta exhaust to be "knackered" when I have the manifold and cat before me but just don't see that. It's amazing what people jumping to conclusions can yield. I need to re-evaluate my whole existence at this point ?

 

 

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I'm with Jon all the way here. Early synthetics did not have a good reputation, I'll grant you, but modern fuels, using modern synthetics, are a whole different ball-game.

 

1) All that castor does is varnish things up - inside and out. It belongs in a museum, not in an engine - regardless of the age or design of said engine. In extreme cases, I've seen it turn into lumps of coke inside the silencer (yes, really)!

 

2) The only reason we use the amount of oil that we do is because some manufacturers refused to warranty engines run on lesser amounts.

 

I was peripherally involved in the development of Bekra heli fuel many years ago (I was used as a test bed!). Initially, this used 15% oil, and we never had a problem with it - in any engine, even under the most extreme conditions. The oil only got increased to 18% as OS warranty was apparently only valid if this (or more) was used. All that increasing the oil content did was make the model messier!

 

I use it in everything from Cox .049s, through old middle sized OS/HB/Super-Tigres up to vintage Webra, modern Super-Tigre and OSs, and even 4-strokes. Frequently these are in helicopters, which on hot, summer days (when we get them!) is probably the harshest environment you could wish on an engine (marginal cooling).

 

Before electric took over the contest scene, the Japanese heli team used to use a fuel that had 30% nitro and 5% synthetic oil! I never saw any of them suffer an engine failure.

 

In recent years (decades?) I have never had an engine issue caused by lubrication failure. Indeed, the only thing I've noticed is that engines that are "tight" initially can take longer to bed in, due to the improved lubrication of modern synthetics.

 

Nothing would persuade me to put castor oil in any of my glow engines. The only reason I use it in diesels is the absence of a readily available alternative.

 

--

Pete

 

Edited by Peter Christy
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19 hours ago, David Ovenden said:

Well I think this topic has run now its course! It would be a shame if the thread ends up falling into the old elephant trap of  "castor vs synthetic". I have made my decision and just need to get on with running the engine. Thanks for your all thoughts and ideas. I will report back once the engine has been run a bit. 

 

Agreed David. Time to close this thread. 

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