Non-ringed engines

[lbk]

I was looking at a OS .91 on ebay and it is "non ringed" whcih I assume means it does not have piston rings. Is this something that I should stay away from? Are non-ringed engines not as gooda s ringed engines? Thanks.

[ser00]

Hi IBK,

There are basically two types of engines that you can buy nowadays - ringed and ABC(non-ringed). Either engine type is good on their merits. The ringed engine (ie Super Tigre G-51) will take longer to break in and will last a long time. When it finally loses compression, all that is needed most of the time to fix it is a new ring and then you have many more years of use out if it. ABC engines break in quicker and initially have more compression (and therefore more power) due to the tapered design of the piston sleeve. As the engine is used more and more, or you run it extremely lean, it will lose compression and the only way to fix it is by replacing the piston and sleeve. This can be very expensive, almost to the point to where it is simpler to buy a new engine. I have both types of engines and I run my engines slightly rich (I use a larger engine size in my planes to I can run a little richer). Compression wise, they feel like new engines.

Happy Flying!