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Old Dec 03, 2009, 11:47 AM
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USA, MI, Muskegon
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ringed vs non-ringed

First i already know one has a piston ring and one doesnt.I'm looking for pros and cons for both engines.Piston and cylinder differences.A perfect example would be super tiger makes a g-61 ringed and g-61 abc why?Thanks to all who respond.
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Old Dec 03, 2009, 12:35 PM
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ABC sleeve is tapered smaller at the top, and expands close to parallel when reaching operating temperature. Break-in is faster, and should be done with a leaner mixture. (rich mixtures can prevent liner expansion and cause rapid wear) Ringed engines need a richer mixture to keep ring from overheating and losing tension, and to wash away break-in particles from the cylinder. ABC engines stand more heat, (lean runs) than ringed as heat can anneal the ring and make it lose tension. ABC is usually restricted to smaller sized engines, (usually .90 size or less) Ringed engines are usually cheaper to produce and repair. ABC engines need both piston and liner replaced to restore lost compression. Ringed engines can be repaired with just a ring if the piston and liner isn't too scuffed up. Another issue is that ringed engines can usually ingest more dirt/foreign matter than an ABC engine without causing a loss in compression. Ross
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Old Dec 03, 2009, 01:03 PM
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Everett Wa.
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The real difference is in friction. As the piston speed goes up the heat generated also goes up. Since heat is energy one loses much of the added power as the RPM goes faster to the drag of the piston and/or ring. At some point the energy lost to the ring exceeds any power gained by the rising rpm. So the short of it you start to loose power at a lower rpm with a ringed engine than you will with an ABC / AAC engine. This is why all high performance model engines are ringless, ether ABC or AAC systems.

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Old Dec 03, 2009, 02:22 PM
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Yea, what he said. Ringed engines seem to start a little harder but not much. And a piston ring is really pretty cheap in comparison to a piston and liner when it comes to rebuilt.
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Old Dec 03, 2009, 04:21 PM
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Tokoroa
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The difference is pretty academic these days.

A good ABC engine will last almost forever so the price of a P/L set is not all that relevant any more.

ABCs are best in smaller displacements (ie: .61 and under) whereas larger engines .90+ are almost universally ringed due to easier manufacturing.
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Old Dec 03, 2009, 07:53 PM
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Everett Wa.
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Just a few minor points.
An ABC system will allow the ports to flow better (for the same timing) as it doesn't need the ring support bridges that a ring cylinder does in the ports.

As to repair. A ring engine should have the cylinder liner re-honed to true up the bore and offer the ring a new surface to bed into (break in). I find that most automotive speed shop will do this for free. After all these guys love engines just as you do. This should be done with a ridged hone. Not flex balls, sand paper of a brake cylinder hone. These are all better than nothing but not near as good as a ridged hone.

On the start question I find that a properly fitted ring is a little easier to start than an ABC set up.

As to durability. For sport/ competition engines in the 6cc to12 cc range I usually exchange my ABC system for a ringed system if I plan to run the engine below 14k rpm. If I think I'm going to run between 13K to 16K rpm I like to use a dykes ring (a very low tension L shaped ring). If I know the engine will be run above 17K I chose an ABC set up. If I know the engine will run above 20K there is no doubt that I will need an engine that has an ABC or better yet an AAC system in it. Note these are not hard rules. As some of you know I ran a ringed version of my Webra long stroke engine for my day to day practice but would switch to the ABC version during the competition season.

Not all ABC systems need to have the piston and liner replaced as a set. Fox, Nelson and Picco offered oversized piston in 0.005 mm ( 0.0002") steps. PICCO even offered pistons rough cut (oversized 0.15mm) for those of us that needed them. If the cylinder is fine an ABC engine can be repaired rather inexpensively. (In reality this doesn't happen often. They also don't wear out as fast as the ringed engine.)
Another note;
While a true high performance engine might cost more up front. If the manufacture is a service oriented organization they often are much cheaper in the long run than some brands that abandon you saying that the performance engine comes with no warranty due to the high performance nature of the engine.

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Konrad
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Last edited by Konrad; Dec 03, 2009 at 11:27 PM.
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Old Dec 04, 2009, 02:20 AM
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Friction is not dependent on surface area. It depends on material in contact. However, lubrication does depend on surface area. Ringed engines have less surface area in contact with the wall thus needing less oil than nonringed.
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Old Dec 04, 2009, 07:21 AM
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The pinch area on the piston of an ABC engine is usually only about 1 mm wide. This is about the same width as a piston ring. On an ABC engine this area is in contact with the cylinder for approximately 25 of crankshaft rotation. With a ringed engine the contact time is 360 of crankshaft rotation. It has been my experience that the ABC engine can tolerate less oil in the fuel than a ringed engine. Now a lapped cast iron piston in a leaded steal liner needs much more oil than a ringed engine.

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Konrad
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Old Dec 05, 2009, 12:19 AM
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I'm kind of old school in that I grew up with piston rings long before ABC was developed. After reading all the stuff about being careful with ABC, particularly the method of breaking in and never running them rich, I was very wary about them but now I've changed my mind because they're not as delicate as some believe. I've changed my mind for two reasons, one being that I deliberately "abused" a new ABC by running it as rich and cool as possible for 45 minutes and at the end the pinch was unchanged with virtually no visible wear when I stripped it down although the rod was running in very nicely. The second reason is that with a running engine there should be no metal to metal contact so long as an oil film is present even if a "pinch" is present. The oil film builds up a very high (hydrodynamic) oil pressure if the "pinch" tries to squeeze it out and this both expands the liner and compresses the piston no matter what the temperature may be. This is the same pressure that keeps an oil film between the rod bush and the crankpin. Piston rings skate across the oil film like water skis or an aquaplaning tyre on a wet road except close to the top and bottom of the stroke.

Rings have the advantage that they're very cheap to replace and are much more dirt tolerant but an air filter helps with both types of engine, especially ABC.

Treated properly, both types should have very long life spans. The only type that can be somewhat difficult to hand start are those using Dykes rings. Rings are unsuitable for very high speed engines (~20,000+) where the rings start to flutter in the groove but for normal sport engines they're fine.
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Old Dec 05, 2009, 09:29 PM
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excellent information guys thank you.bth9318
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Old Jan 01, 2010, 06:28 PM
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Quote:
Originally Posted by downunder View Post
I'm kind of old school in that I grew up with piston rings long before ABC was developed. After reading all the stuff about being careful with ABC, particularly the method of breaking in and never running them rich, I was very wary about them but now I've changed my mind because they're not as delicate as some believe. I've changed my mind for two reasons, one being that I deliberately "abused" a new ABC by running it as rich and cool as possible for 45 minutes and at the end the pinch was unchanged with virtually no visible wear when I stripped it down although the rod was running in very nicely. The second reason is that with a running engine there should be no metal to metal contact so long as an oil film is present even if a "pinch" is present. The oil film builds up a very high (hydrodynamic) oil pressure if the "pinch" tries to squeeze it out and this both expands the liner and compresses the piston no matter what the temperature may be. This is the same pressure that keeps an oil film between the rod bush and the crankpin. Piston rings skate across the oil film like water skis or an aquaplaning tyre on a wet road except close to the top and bottom of the stroke.

Rings have the advantage that they're very cheap to replace and are much more dirt tolerant but an air filter helps with both types of engine, especially ABC.

Treated properly, both types should have very long life spans. The only type that can be somewhat difficult to hand start are those using Dykes rings. Rings are unsuitable for very high speed engines (~20,000+) where the rings start to flutter in the groove but for normal sport engines they're fine.
I've been using the Bruline air filters since they came out and believe that is one of the reasons that I've had such good luck with my engines. An air filter and fuel with 20% oil content. Never had any problems.
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Old Jan 01, 2010, 06:48 PM
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Quote:
Originally Posted by Konrad View Post
The real difference is in friction. As the piston speed goes up the heat generated also goes up. Since heat is energy one loses much of the added power as the RPM goes faster to the drag of the piston and/or ring. At some point the energy lost to the ring exceeds any power gained by the rising rpm. So the short of it you start to loose power at a lower rpm with a ringed engine than you will with an ABC / AAC engine. This is why all high performance model engines are ringless, ether ABC or AAC systems.
Friends don't let friends fly nickel,
Konrad
That's good to hear. I saw that the engine sold under the Tower Hobbies brand is an ABC.

http://www3.towerhobbies.com/cgi-bin...?&I=LXJA86&P=7

Frank
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Old Jan 01, 2010, 07:04 PM
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Everett Wa.
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Now the converse is not true, that all ABC engines are high performance engines
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Old Jan 01, 2010, 07:04 PM
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Originally Posted by Murocflyer View Post
That's good to hear. I saw that the engine sold under the Tower Hobbies brand is an ABC.

http://www3.towerhobbies.com/cgi-bin...?&I=LXJA86&P=7

Frank
Too much Nitro maybe?
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Old Jan 01, 2010, 07:06 PM
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Everett Wa.
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Originally Posted by Broken Wings View Post
Too much Nitro maybe?
Breaking off of a lug looks more like impact damage. Do you have a photo (clear) of the rod?
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