Thanks Tim

The Enya 29-IV (5224) does have a CI piston and steel liner. I have an Enya 'Owner's Instructions' and it says 20% oil. I have some Brodak 23% oil (1/2 castor-1/2 syn) fuel that I run on some other engines that should be OK based on the instructions. But I can also add a bit of castor to get the total oil up to 25%. Are you suggesting that this is the way to go for this particular engine?

I also saw a past post from Randy Smith where he mentions 23% oil (1/2 castor) is OK for the Enya 29-5224.

I picked up a stock Enya 29 - 5224 (round venturi version)......

It takes me just an hour or so to break in an Enya Iron P/L engine.

Enya Engines with Iron Piston and Liner (not other types) has a reputation for taking too long  to fully break in, and  that is true If the break-in is done just letting the engine run rich as you normally do with other engines.

Iron Enya engines has very good metallurgy that is hard to wear out and they come with very tight fittings from Factory.  That is why Enya engines are hard to start in the beginning and without proper break in they can  quit when it gets hot. Iron piston gets bigger than the liner when it gets hotter, exactly the opposite of ABC engines. When the piston expands it creates so much friction that the engine quits, but as soon as you flip the prop it is back to normal, and there is absolutely no harm to the engine when this happens (if you use mostly castor oil fuel). 

A special breaking is required so when the engine gets hot the piston will smoothly match with the liner with minimum friction.

I have been getting great results with this break in method that takes just one hour or so on the bench.

First Phase – Thermal Treating
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I do 10 short runs of 1min with the needle set so the engine is breaking to 2 in short bursts, letting the engine totally cool down between runs. Then 8 short runs of 2 min and then 6 of 3min (perhaps the 6x3min is not necessary but I do it anyway)


Second Phase - Unleashing the Power!
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3 to 5 runs of 6 minutes with the same needle setting as in Phase 1. Depending on how tight the engine is, it may require more or less runs. In this phase I pinch the fuel line with care, leaning  the mixture to the absolutely highest rpm I can get and keep it there for 10 seconds, release the fuel line, wait for about 25s and repeat the process till the end of the 6 minutes.
It is important to understand that you need to get the engine to the max rpm possible, not just higher rpms, that is key in this process, otherwise it will take a lot more time to break in.
The top rpm will improve significantly in this stage.  We do want the engine to get very hot for the piston to grow, this will cause the P/L  to lose the excess particles to match with each other perfectly.  The engine will end up with strong compression and will start cold or hot very easily.
USE ONLY CASTOR OIL FUEL IN THIS PROCESS!!!  Absolutely no Synthetic oil!

Then go flying and after about 50 flights using all castor fuel, it will be ok to start using Blend Fuel with Synthetic oil because the engine should be running cooler by now with less friction between P/L. I have been using Byron 10/20 with castor added to 23% total oil and after many many flights with this fuel my Enya SS30 is just perfect!

Martin

p.s. do at your own risk!  A friend of mine did 2nd Phase  only from the start and saved a lot of time! Unfortunately he went to RC and died a few year later, so I am not sure what happened with that engine in the long run, but the Enya SS25 worked quite well on  his Ringmaster at Brodaks 2008.

To add to Brian's information, I have a brand new ENYA 35 #5224 with a ball bearing front end.
Anyone know about this version?
Bob Z.

Hi Colin,

> I have about 1.5 hrs on the Enya 29-5224 on my test stand. I did basically follow your break-in method above.

> I have been using Brodak 5% nitro / 29% all castor fuel for break-in cuz it is what I have. Engine seems to run fine. Pinch the fuel line to max rpm and release, and it settles down quite well.

Great! 

> I am ready to try it out in the air. But is 29% all castor too much oil for the first series of flights? Downside to that much oil for the initial flights?

Fuel with too much castor oil is not desirable for flying with tight clearance cylinder/piston engines like the Enya.  Oil increases fuel viscosity which reduces fuel draw (can be a real problem in cold climate), less power, fast varnish built up. A tight clearance engine will not do well with varnish built up, you go back to the problem with too much friction and heat.

> I also have 23% oil (50/50 castor/syn). Stay away from that for now until x-many flights?

this is a very good mix for flying with this engine,  but to be safe, use only after you are sure the engine is running free and smooth. You also do not want to keep using all castor fuel for too long to avoid the varnish built up.

Martin

These are a bit of an odd one because they were known as a model 5224 35-III BB Special from around 1965/66 and seemed to precede the 29-III BB Special. Unlike the 29 they were never known as the 35-IV or 35-IVB, presumably because they only ever had the square venturis. Obviously they could never be used in B team race where 29 (5.00cc) was the maximum size. Very early ones (and extremely rare) used a convex radius prop driver and nickel plated screws before the switch to black screws in 66.

Thanks Martin

I flew my model w/ the Enya 29-5224 today. Was not a great experience. No crash or anything like that, but the engine just ran poorly. (I did previously do the bench break-in as you have suggested using 5% nitro-29% oil all castor). And about 1.5 hours on the bench.

Vitals:
5 nitro - 29 oil (all castor)
Profile mounted engine (Carl Goldberg Shoestring)
10-5 MAS prop
Oval profile uniflow fuel tank
Muffler pressure used
(My Enya 29 is the round venturi version)

Engine started very easy each time. Just a few flips needed. I ran it on the rich side since I realize it is still breaking in. Engine ran reasonable in level flight (considering it was set rich). But I tried a simple loop and it quit at the top of the loop. It was not doing a good 4-2. So I thought too rich initially.

I did about six 3–4-minute flights. On successive runs I kept leaning it out a bit, but basically it still kept quitting at the top of the loop.

Thoughts welcome. Just needs more run-in time? Change to different fuel mix?

Maybe 29% all castor is just not OK. The owner's manual says minimum 20% oil. I can try the Brodak 23% oil (50/50) mix on my next runs. I can also add castor to boost the total oil up to say 25% if recommended for the break-in period.

What fuel do you recommend I use as the engine continues to break-in?

Pics of my setup attached.

Thanks in advance.

Martin, here is the head for my 29-5224. Looks to me to be the low compression design. Can you please confirm. And when I took it off there was no head gasket. Should there be one for a stock Enya?

You have the High Compression Head, which I think will work well with 0% Nitro and save you some money.  If you want to use nitro then you may need to find a low compression head for your engine.  Try to work with this head, change only if the engine is too aggressive when flying.


The venturi is too big and you definitely need to get a new one.  Enya has available venturis from 6.5mm to 8.0mm.  I recommend you try the 7.0mm with Nitro and  7.5mm with 0% Nitro.  Venturi size depends on the climate where you fly.  if at sea level you probably need to get the smaller 6.5mm venturi.

I suggest you get an NVA from Randy Smith, that NVA is the best right now. You will need to use some washers to center the spray hole, and I suggest you seal everything with silicone when you mount the NVA.

At the time Enya sold engines with 2 heads and 3 venturis, so people could tune their engines to different applications.


Martin

Yes! Every engine has its particular tank height and run characteristics.

John Miller posted some time ago this Tank setup and that is what I have been using, with the taller side in the vertical on profiles models.

What I have learned is that the Engine cares only about where the uniflow exit height is, not so much where the center of the tank or the pick-up point is.