Right fuel for a "new" old Enya

[David Ovenden]

Firstly, just to be clear, this post is NOT about what is the best fuel for model engines. 

I have acquired an Enya 15-IV engine. This engine was produced I guess in the  early 70's. So it has old technology and metallurgy. However, it has never been used , mounted or seen fuel. So it needs running-in from scratch. I use nothing but fully synthetic fuel in all my engines (nearly always Prosynth 10% but I do have some Model Technics Laser 5% too) Most of the forum posts I have seen (mostly US-based) talk about only using castor based fuel (with at least 20% castor) with these old cast iron, steel liner Enyas. However Engine Doctor on an old post on this forum hinted that while that might be the correct policy for old engine that previously ran on castor based fuel, it may not apply to unrun "old" engines.

So my question is:  

Do I run this unused Enya 15-IV engine on modern synthetic fuel right from the start? Or, might it be wise to add some extra castor oil to my Laser 5% fuel for the running in period and then revert to standard synthetic oil fuel. Or do I need to (against all my instincts) get hold some Castor based fuel and use that just for this old Enya? Or something different ? 

I am interested in your thoughts about this specific engine and the right fuel for it. Please don't get into general debate about castor vs synthetic. Its been done to death, and just causes "overheating" and "friction"  on the forum which is the opposite of what any good lubricant should do!!

Edited July 29, 2021 by David Ovenden

[Peter Christy]

One of my models has an OS15 of similar vintage in it. Runs fine on fully synthetic.

 

Indeed, I have quite a few old engines, my favourite being a Webra 61 that I bought in 1967. Despite having run on castor for decades, when brought out of retirement I switched it to full synthetic with no issues.

 

Castor belongs in a museum, not a model engine. A good synthetic is infinitely better.

 

--

Pete

 

Edited July 29, 2021 by Peter Christy
typo!

[Engine Doctor]

Hi David . You Enya has as you say old technology so won't develop as much power and heat as a modern engine . As its new then an oil rich fuel for running in is a good idea. A drop of castor added to your synthetic fuel should be OK for the Enya if it has iron piston and steel cylinder. A drop of castor may help prevent any scuffing during first runs. Once fully run in then synthetic should be OK. If its an ABC set up then synthetic from the first start.

I ran an old Enya 25 in a fun fighter some years ago on synthetic fuel . That had an iron piston and it was fine despite it being given a hard time . 

One thing about Enya is they have the best quality materials so should be fine if run in correctly.

[David Ovenden]

1 hour ago, Peter Christy said:

One of my models has an OS15 of similar vintage in it. Runs fine on fully synthetic.

 

Indeed, I have quite a few old engines, my favourite being a Webra 61 that I bought in 1967. Despite having run on castor for decades, when brought out of retirement I switched it to full synthetic with no issues.

 

Castor belongs in a museum, not a model engine. A good synthetic is infinitely better.

 

--

Pete

 

Thanks for the input Peter. I am seeing Tony H (one of your flying group) today and the  purchase of this engine is partly to do with you both! He flew your old Veron Robot model recently and really liked it. I am helping him here in  France with his electric model. I am wondering about building a "Robot-style"  model for the Enya so he could get some flights in with it. Sort of retro-style training but with a buddy box!! I learnt to fly on my own in the 70s with a plan-build Radar model (quite like a Robot) fitted with an Enya 15 and HB kit-build radio.

[Jon H]

One thing i would suggest is you resist the temptation to run it slobbering rich. If it is a ferrous piston/liner you do need to get it hot or it wont work out too well. Its all about the expansion and work hardening, you need the heat. Dont thrash it quite as hard as an abc, but get the revs up and get some good heat into it. Say 90% of peak tune in short bursts. 

 

On the fuel, i would use the laser 5 from the get go personally. A friend at my old club had a similar enya and we ran it from new on the laser 5 without any problems at all. 

Edited July 29, 2021 by Jon - Laser Engines

[David Ovenden]

53 minutes ago, Engine Doctor said:

Hi David . You Enya has as you say old technology so won't develop as much power and heat as a modern engine . As its new then an oil rich fuel for running in is a good idea. A drop of castor added to your synthetic fuel should be OK for the Enya if it has iron piston and steel cylinder. A drop of castor may help prevent any scuffing during first runs. Once fully run in then synthetic should be OK. If its an ABC set up then synthetic from the first start.

I ran an old Enya 25 in a fun fighter some years ago on synthetic fuel . That had an iron piston and it was fine despite it being given a hard time . 

One thing about Enya is they have the best quality materials so should be fine if run in correctly.

Thanks ED. I will probably just add a little castor to my normal fuel for the first  few runs then revert to my usual synthetic fuel.

Edited July 29, 2021 by David Ovenden

[David Ovenden]

3 minutes ago, Jon - Laser Engines said:

One thing i would suggest is you resist the temptation to run it slobbering rich. If it is a ferrous piston/liner you do need to get it hot or it wont work out too well. Its all about the expansion and work hardening, you need the heat. Dont thrash it as hard as an abc, but get the revs up and get some good heat into it. Say 90% of peak tune in short bursts. 

 

On the fuel, i would use the laser 5 from the get go personally. A friend at my old club had a similar enya and we ran it from new on the laser 5 without any problems at all. 

Thanks for the info Jon. I will avoid over-rich running and keep it hot. Good to know that Laser 5 fuel worked well in your friend's Enya.

[Jon H]

This is an old article and while it relates to diesels the principals involved are the same for your enya. You can ignore the bit about extra oil and compression settings. I would also tend to use a smaller prop than normal not larger as combat diesels tend to use much smaller props than r/c would normally so the point of reference isnt the same. Something like a 7x5 or 6? I think i used to run my OS 15fp on 8x4 but it was run in by then. 

 

Anyway have a read and see if you find any of it useful

 

https://web.archive.org/web/20190917165855/http://www3.telus.net/dieselcombat/about_diesels.htm

 

Again on fuel, my Enya 53, 120, 155 and 240 all run on laser 5 without issue. They are all 4 stroke but still, fuel is fuel. 

Edited July 29, 2021 by Jon - Laser Engines

[David Ovenden]

1 hour ago, Jon - Laser Engines said:

This is an old article and while it relates to diesels the principals involved are the same for your enya. You can ignore the bit about extra oil and compression settings. I would also tend to use a smaller prop than normal not larger as combat diesels tend to use much smaller props than r/c would normally so the point of reference isnt the same. Something like a 7x5 or 6? I think i used to run my OS 15fp on 8x4 but it was run in by then. 

 

Anyway have a read and see if you find any of it useful

 

https://web.archive.org/web/20190917165855/http://www3.telus.net/dieselcombat/about_diesels.htm

 

Again on fuel, my Enya 53, 120, 155 and 240 all run on laser 5 without issue. They are all 4 stroke but still, fuel is fuel. 

Thanks Jon. I have  had a read and will try out the "heat/cool/heat/repeat" technique when running in. 

[Peter Christy]

21 hours ago, David Ovenden said:

Thanks ED. I will probably just add a little castor to my normal fuel for the first  few runs then revert to my usual synthetic fuel.

No! No! No! All that will do is varnish up the inside of the engine - especially if the engine is run hot. Modern synthetic fuels, as suggested by Jon, need no additives - especially not castor! All these rumours about "needing to add a little castor" date from decades ago when synthetic oils were in their infancy, and there were some very duff ones around. Modern synthetics are fine on their own, and need no help.

 

Say Hi to Tony for me! That Robot had the OS 15 in it, and is going up to Pontefract with me for the "retro" meet this week-end. Plans are still available for it, and I can thoroughly recommend it as one of the best trainers around!

 

--

Pete

[Frank Skilbeck]

Interesting thoughts, I have a NIB Enya 19 and when I manage to source a replacement for the missing exhaust bracket, I'll be running it on synthetic.

[Martin Dance 1]

It's worth remembering that glow fuel with a synthetic oil is not new technology. I ran an OS25 on synthetic in the 1970's. First with Castrol MSSR, not particularly successful. Then  a fuel with ML70. The engine had many gallons through it without issue. I believe ML70 has been developed over the intervening  years so using it in a 'new' old engine shouldn't be a problem I stopped using the ML70 based fuel as the supplier, GMax fuels stopped making it in model quantities.

[J D 8]

         I run several Enya's from 15's to 90 four stroke's, all use the same synthetic fuel. Most have seen some time with castor in the past but one nib box 15 purchased 2 years ago has run only on synthetic and been fine.

[David Ovenden]

1 hour ago, Peter Christy said:

No! No! No! All that will do is varnish up the inside of the engine - especially if the engine is run hot. Modern synthetic fuels, as suggested by Jon, need no additives - especially not castor! All these rumours about "needing to add a little castor" date from decades ago when synthetic oils were in their infancy, and there were some very duff ones around. Modern synthetics are fine on their own, and need no help.

 

Say Hi to Tony for me! That Robot had the OS 15 in it, and is going up to Pontefract with me for the "retro" meet this week-end. Plans are still available for it, and I can thoroughly recommend it as one of the best trainers around!

 

--

Pete

Pete,

I downloaded the Robot plan and just been having a look at it. I would want to change the 1/16" ply elevator though (that was intended for single channel use) to something more suitable for today. I would redesign a bit to make the elevator within the outline of the tailplane. The wing section is interesting. It says on the plan it is NACA 2412 but on the plan it shows the wing rib profile with a completely flat/straight line lower rear section and then a "flicked-up" trailing edge. (no doubt for ease of construction on the plan for novice builders) Might just redraw the rib to be really NACA 2412 profile, especially as the front of the rib has to be re-drawn anyway as the custom Veron LE  profiled balsa isn't available . Still, will make a nice project.

Will say Hi to Tony for you

David

RE fuel. Well I don't have any castor oil in stock so it would be hard to add!

[J D 8]

             The last bit of castor I had went in the Briggs and Stratton of my old lawn mower just for that old time racing smell.

[Nigel R]

2 hours ago, Martin Dance 1 said:

I stopped using the ML70 based fuel as the supplier, GMax fuels stopped making it in model quantities

 

I thought MT still used ML70 in their fuel?

[Jon H]

1 hour ago, Nigel R said:

 

I thought MT still used ML70 in their fuel?

 

laser 5 and laser 5 pro use it, as does goglo i think

[Ace]

Southern Modelcraft fuels use it in Laser and other synthetic mixes. 

[Phil Olson - Model Technics]

I think he means G-Max stopped making fuel ( over 30 years ago ) but still make ML70 which gets sold all over the world

[Peter Christy]

On 30/07/2021 at 10:28, Nigel R said:

 

I thought MT still used ML70 in their fuel?

I don't know about their other fuels, but Bekra Heli fuel uses Klotz, with a trace of EDL, if memory serves me right. Despite being labelled as a heli fuel, it is a very good general purpose fuel, and I use it in everything, from Cox .049s, via vintage aero engines and 4-strokes!. Helicopters are a very harsh environment for a model engine (marginal cooling), so if it works in that environment, it will be OK in just about anything. Available in a variety of nitro percentages, and even straight (if you ask nicely! ? )

 

Full details of al their fuels - and what's in them - on their website!

 

--

Pete

 

[Model Monster]

I acquired a new Enya 60 2st about a year ago, to go in my Ganster 63. I had the same query as the OP and contacted Enya with the specific query can I use fully synthetic etc. Their response was 20% fully synthetic plus 2% castor. I got Southern Modelcraft to mix me a few gallons with 10% nitro and have used at least 2 with no issues. NB it does seem happier running a bit rich, so make sure your model's fuel proofing/ covering is up to it.

Edited August 1, 2021 by Model Monster
Typo

[Jon H]

22% oil?!?! madness

[John Minchell]

The more oil in the methanol or petrol / oil mix, the weaker you are running the engine at the same fuel consumption rate. 

Maybe why you needed to run it "rich" so that it actually wasn't running lean - assuming that none of the oil was being burnt.

A common missunderstanding some two stroke motorcycle racers had back in the day, more oil means leaner mixture so needs bigger carb jets for the same correct combustion.

 

[Frank Skilbeck]

Not quite on a model engine John as you adjust the needle to get the correct Methanol/Nitro to air ratio. But yes you will use more "Fuel" at a higher oil content just because you need to increase the fuel flow to recover the volumetric flow of methanol/nitro. Conversely if you reduce the oil content you have to screw in the needle or the engine runs rich. If you reduce the oil content from 20% to 10% the volumetric oil flow through the engine is reduced by around 56% due to the extra methanol needing a "leaner" mixture.

 

BTW anybody know where I can get an exhaust bracket for an Enya 19 VI, I have a NIB one but no bracket to hold the exhaust on.

Edited August 9, 2021 by Frank Skilbeck

[J D 8]

           When the bracket on my Enya 15 broke I made a replacement from a jubelee pipe clip.