Question: what's the difference between a ringed engine and a nonringed one? (other than the ring of course)

What are the advantages/disadvantages of going with either one?

thanks,,,

A ring engine uses the ring to seal the gap between the piston and cylinder. A non-ringed engine uses the piston wall as a seat against the cylinder.

thanks, are there any advantages or disadvantages of going with one versus the other?

It takes fewer hours to break in a non-ring engine.
Ringed engines tend to last longer.
Other than that, I really don't know.

A couple more points to consider based upon literature I have read:

Ringed engines are typically more expensive than non-ringed.
Ringed engines take longer to break-in (as Geistware mentioned).
Ringed engines will last longer before requiring service due to compression problems, and compression problems are much less expensive to repair - just replace the ring.
Ringed engines are less efficient (use more fuel for less power), due to blow-by past the rings.

Sorry strato but I'd have to disagree on a couple of things.

Some manufacturers offer the option of either ringed or ABC (OS do this with some of their engines) and in that case there's no difference in price or power. Blow by is virtually non existent under running conditions once the ring is properly run in and seated.

The only disadvantage of rings is that it takes much longer to run in enough to be flyable and a totally different running-in technique has to be used. Ringed engines are far more dirt tolerant.

I've never worn out the rings in any of my engines even after a LOT of use so it's hard to say how long they last

i've had dozens of each and the ringed engines are the quickiest to break in good enough to be reliable in 1 tank of fuel for a good os motor on some of the hi performance abc or acc maybe a gal
of fuel the advantage of the ringed motor lasts longer than the plane(haha)if it gets weak replace the ring cheap repair.if you'll looking for power a non ringed is the only way to go.
roy

I stand corrected on the price, but if it isn't due to blow-by, then why do they produce less power? Same fuel, same prop, same engine manufacturer, 1000-2000 RPM less.

I've never seen worn out rings either, but I DID say they lasted longer.

The main differance is the non ringed or ABC type engine has a tappered cylinder giving high compression at the top of the stroke, the ringed engine has a constant bore cylinder , this is the main reason for the power differance, in some ringed engines the Piston may be Steel vs Aluminium in the ABC type engine, the lighter piston can be ran at higher rpm. The cylinder in the ringed engine may also be steel vs Nickle or Chrome, not quite as friction free.

the ringed engine can be more consistant in tempature changes, going from running in cold weather will not effect starting as much as a non-ringed , a ringed engine is cheaper to renew compression and is less suseptable to damage from dirt or forign matter in the engine sence the ring can skip over or just push it on threw . The ring can also be damaged quicker by overlean runs because of the lack of Lube.

I personnely see the ringed engine as being more consistant, and longer lasting .

The ABC can develope more power, but I haven't seen the 2000 rpm differance , this can greatly depend on the prop being used.

The only thing you can compare side by side is the ringed and non ringed of the same model, don't compare the FX with a SF or FSR , differant models have differant porting as well which can give higher rpm for a given size engine.

The .46 SF came in ringed and nonringed, the power advantage with the ABC engine was not that noticable IMO. I still have the ringed engine, almost worn out it still turns a 10X7 around 14,000 rpm.

thanks,,,

For a very good discussion of both engines and their pros and cons (beyond the very good info you've received here), I would strongly recommend the blue book on 2 Stroke Engines. I'm at the office and don't have it here to give you the complete reference, but its title is "2 Stroke Engines....." Its blue and is always advertised in the back of Model Airplane News.

I bought it from Amazon.com and went from being engine illiterate to knowing more than all but the engine gurus at the field! A very good reference, and it gives detailed directions about properly breaking in both kinds of engines, the process is very different and will drastically affect its life.

See ya,
Heath

thanks, I'm interested in the book. If you're able, can you please post it?

"2-Stroke Glow Engines for R/C Aircraft"
by C. David Gierke

Great book, best $15 I ever spent.

Heath

Another thing about ABC engines is that you shouldn't run them
too rich, as that would make them run cooler, and ABC engines
depend on operating temps to create a good seal between the
piston and the cylinder wall. Lots of people get used to breaking
in engines one way. They set them up ultra-rich, gurgling, almost
4-cycle type of running-in. That would be fine for the ringed ones,
but run the ABC engine a little leaner, to get the temperature up.

By the way, do you fly at the Bandera field there in San Antone?
I'm from S.A. originally, and have flown there. Very short final
approach from the west...

Jesse

Jesse, thanks for the reply. I'm thinking the ringed variety would be best for me,,,especially that I just beginning to get into glow. I've flown epower for a little over two years.

No, I haven't flown at the Bandera field. I think that club is called S.A. Propbusters. Nevertheless, I have been there several times just to watch. Yes,,,,,a very short final approach. lol,,

take care,

Ok, so I have a question. I have a OS 46 FX and a OS 46 SF, which is better? What would be the main difference in break in and use?

the 46 sf was available in ring or abc the fx from what i can dig up is only abc the fx has a larger squarer head and a little longer crank shaft. if you have a non ring run it more towards the leaner side they like to run more hotter then the ringed engines
but don't over do it. there is a problem if you run a abc too hot
the liner will peel off the cylinder wall .proberly a good guess is to run 30 - 40 degress hotter then the ring version a temperture
gauge is handy.if you want the extra power the abc is the way to go just need to be a little more carefull with them. i've had a lot of both and i've never had a abc go out yet have had to replace a few rings. i've run some of the abc motors with as much as 50%
nitro and they are still running.most of your engine life depends on how you operate and take care of your motor.
roy

fredericksburg,va.

The FX series also has the needle vavle moved to the engine's backplate, rather than being on the carb as it was with the SF. Remote needles like this make it a bit safer to adjust the mixture.

I seem to remember that the SF series were true ABC engines, where the FX is ABN, with nickel replacing chrome in the engine's manufacturing.

Is it possible to convert the needle valve on the SF to the back?

While we're on the subject, is my old K&B .45 Sporster an ABC engine? It does not have a ring, but to my understanding, aren't the ABCs' piston tapered? It seems like the piston on mine is uniform.

You can't see the taper, and when the engine reaches operating temperature, the top of the cylinder, near the head, expands more than the bottom of the cylinder leading to a uniform diameter.

hello Geish:

I abelive all K&B Sportsters were ABC. I have a Sportster 65 it is a greeat motor. The Sportsters are however a Plain Bushing engine. They do not like to rev real high. Put a bigger lower pitched prop on it and keep it around 10 grand and the engine will love you. And I hope you love it. Just remember Sprtsters are luggers.