G'day

I have recently bought an Enya 45SS ring engine. I have also been running it in on a test bench.

The instructions are pretty vague but as it is an engine with a hardened steel liner, aluminium piston and a cast iron ring I have been giving it short (2 to 5 minutes) rich runs on about half throttle. This seems to be what the instructions suggest.

When it was straight out of the box, it appeared to have very little compression. It now has about 25 minutes running and the compression still seems very low.

I have been using fuel with 25% castor, 10% nitro and 65% methanol and an 11 x 6 prop. I put an Enya #4 plug in it.

It starts very easily, seems to be running happily but I am slightly surprised to find that the compression feels so soft after this period of running. I run my saitos in a similar way and by 20 minutes their compression has dramatically improved. There is clean oil all over the test stand and there does not seem to be any shiny bits or black bits in it.

Any ideas? Have I fried the ring and softened it? Or should I just put it in a trainer and fly it slightly rich. I know these engines do need a long running in. Perhaps I am expecting too much too soon.

Thanks

Mike in Oz

I think you should just fly it.
Enya engines take a long time to finally settle. When the engine is easily starting than there is nothing to worry about.
If the compression is really to low the first thing you will notice is that it is difficult to start..

Kind Regards,

Holm

G'day Holm. Yes, I was thinking along the same lines. It just seems lower than I expected I guess. It certainly is easy to start. Just prime and flick.

Cheers

Mike

Mike,


Why don't you wait for Brian Hampton (downunder) to reply here.

He's an expert on ringed and iron+steel lapped engines; and for those made by Enya in particular.

I had that exact same engine.

When "dry" the compression felt very low but if i added just enough after run oil to line the cylinder walls the compression improved dramatically.

I read a post here recently which stated something about enya's using the oil in the fuel to aid with compression.

BTW, don't forget the carb has 3 adjustments. There is an air bleed which is used to adjust the idle. I was forever chasing needle settings because the airbleed was rich from the factory which tricked me into setting the low needle too lean for a good idle. The result was poor transition in the midrange and back to idle.

Once i realised my mistake and leaned the airbleed slightly it was a great little engine. It is the lightest .46 made. Several oz less than a typical OS 46ax which makies it a great choice if your model is nose heavy.

G'day Mike,

I have no idea what Enya says, but my understanding of running in ringed model engines was that they required high (full) throttle so that there was sufficient combustion pressure to seat the ring and allow it to bed in. So nice and rich for cooling and lubrication and full throttle for sufficient combustion pressure.

Having said that I guess there's no rush to get to full throttle, and I can't imagine that your half throttle running would have done any damage, perhaps just slowed the process down a bit.

I do know that with full size aviation piston engines, if the initial running is done at to low a power setting, there is a possibillity of glazing the bore with the result that the ring never seats. You end up with low power, high oil consumption, fouled plugs, grumpy engineers etc.

There are two things that contribute to the feel of an engine that we describe as 'compression'. One is whether there are any leaks, but the other is to do with the design of the engine ie compression ratio.

A two stroke engine set up for high nitro (low compression ratio) will feel different, when flipped over, to a low nitro four stroke for example.

I'm guessing you know this but when you compared to your Saito it made me think.

Any way I reckon you should go and fly it. Not to lean and not too many long slow high power climbs. Big loops and wingovers help cooling and vary the load nicely.

Cheers

Dave H

G'day everyone.

Dar, I will be interested to hear what downunder has to say. I have seen his many posts on Enyas. His engines are control line so I guess he has to run them at "full throttle".

CustomPC, yes, oil does make things feel better sealed and I did notice the three adjustments. It is an interesting carby. A dual needle plus airbleed. I wonder how many people dismiss them simply because of the hole in the front not understanding that they are fuel metering.

And G&D, I am inclined to fly it but I don't want to do it too soon. I know that automotive engines need to be run in with enough load to get the rings to seat. I once had a 6 cylinder Land Rover engine which I had rebored. I had a terrible time trying to get the rings to bed. I also bought an ex-army Land Rover with the same engine in it. The engine in it had been reconditioned and I was told that the army contract insisted that the engines be bench run before they were delivered and that the rings had to be bedded in in that process. I was told that it took six hours for the technicians to run these engine in. Mine was a beaut. It was the best six cylinder Land Rover engine I ever came across. I was also told that they cost the army about $6,000 each to rebuild. No wonder it was good.

I await downunder's comments with bated breath.

Mike also downunder.

Hi!
All running in should be with full throttle opening! And all adjustments be done with the high speed needle! -Simple as that!
Why? Because that way you know that the engine gets enough fuel!

As your engine is ringed engine it needs a rich running in.
Thast means slobbering rich the first tanks and then gradually leaning the high speed needle. After a few 3-5 tanks it could be flown..or flown the first tank if you prefer that , as long as you set it fairly rich!
Suitable glow plug is an Enya 3 or OS 8.

Runit, tune it rich and fly the heck out of it. After about a gallon or two it will be the most awesomest engine ever.

G'day Mike
Enyas take a very long time to run in the ring so your 25 minutes has barely started it, especially with the half throttle. I've run my new 60-IIIB for over an hour and there's barely any indication that the ring is starting to smooth the tops of the machining marks although admittedly it's only had a couple of quick bursts into a 2 stroke so far. I gave my 61 rear exhaust Enya an hour on the bench and the ring was just starting to bed in but it was good enough to fly with even though the compression "feel" hasn't settled down yet.

My running in starts with it running as rich as possible (without the plug being powered) which is generally at about 6000 revs full throttle and giving it 5 minute runs. I monitor the revs at the 5 minute mark (because it'll gain a few hundred as the tank level drops) then set the initial revs on the next full tank to match the end of the previous tank. That gives a very gradual increase in heat as the revs slowly rise from tank to tank. Enya state that it could take up to 3 hours to bed in the ring so some careful and rich flying does the final bit. One thing to note with rings is that they also need to "run in" the contact area between the bottom of the ring and the piston groove and that's where full throttle (high pressure) helps give a good seal.

The Enya 61 is a bit of a new thing to me though because, although it's ringed, the liner is brass but plated with nickel and a silicon carbide composite (apparently Nikasil!). How this might affect the running in of the liner I can only guess .

Good Morning CustomPC:

Can you recommend a starting point for the air bleed screw? I have an SS .50 Ring that I have been chasing needle settings for about three years! [:@] I have never been able to get this engine to maintain an acceptable idle and transition properly.

Thank you for any assistance which you, or anyone else, may be able to provide!

Regards!

Bob
I got a used Enya 45CX and it was all out of whack, tuning wise and I set the air bleed srew about 1/2 way across the opening for a starting point. I think I remember turning it in about 1/8th turn and it idles low forever, accepts full throttle as fast as a two stroker can and settles down nicely. I use 10% CoolPower, OS #8 plug, and MAS 11 x 6 and it sreams. Some have said to use 10 x 6 becuase Enyas like to run at high RPM's but I find mine runs great at all settings.

Hope this helps. I was about to toss mine in the junk but after spending several hours troubleshooting it is a great engine that should provide years of entertainment!

Scotty

Mike, this is probably a stupid question, but is the compression soft when the engine is turned in the normal direction of rotation, or backwards? If it's good when you turn the engine backwards, then I don't think you have a problem.

I've got an SS35 Ring which was a bit soft to start with, but has come along nicely with running. It has never been difficult to start.

Steve