Ringed pros and cons?
 

New to glow power, what are the pros and cons of ringed -vs- not? Longevity, power?
--Rick

Ringed vs. ABC et al
 

Common sense says that the ringed engine should out last an ABC or ABN type engine since the ring can expand as the cylinder wears, but it seems like the ABC types do not wear much. I have not managed to wear out any engines of either type in ten plus years. It seems that the ABC engine can with stand a hot lean run a lot better, the head bolts came loose on my Irvine Q 72 and I thought the engine was toast, but after re-torqueing the head, it ran exactly as before. I turned a SuperTigre 51 dark gray and cooked the muffler so bad that the pressed on back end came off, a new ring fixed it right up but it stayed dark gray, it was on a Sport 500 Collective Helo and the pressure line came off the muffler, but it did not quit. I think that all engines are pretty tough.

Ringed vs. ABC
 

The engines we fly today are fantastic compared to what was available many years ago. I have been running model engines since 1950, so I have seen the good and the bad.

40-50 years ago, engines with steel liners and cast iron pistons had to be broken in correctly or they wouldn't run well or last any time. Now, most people just drop the engine in and go fly. Doing this may not get you the best performance in the long run, but it does work due to superior metallurgy and quality control during manufacture.

Ringed engines take at least, a few rich runs to seat the ring. If you don't do this, you risk a poor compression seal and less than full power. Many people run these engines lean too soon and then complain that they have less power than a corresponding ABC engine. Once an engine is in an airplane, there is a great urge to lean it to max power no matter what the instructions may say. This may be one of the reasons that manufacturers produce mostly ABC engines, to make them easier for the novice.

As for power, unless you are racing, there is really no difference. Take the new OS .50, for example. It is a ringed engine, while their .46 is ABC (or ABN, however you want to call it). I think you'll find the .50, even though it is only slightly larger, is considerably more powerful.

Ringed pros and cons?
 

The choice of ringed or lapped/honed engine has little to do with power or longevity. At the average sport engine speeds or rpm there is little to choose between them. However things change with high performance high revving engines. The ring has some play in its groove. At the higher rpm the movement of the ring cannot keep up with the piston speed. It gets battered up and down by the piston, cannot take the beating and goes into self destruct mode.

Ed S