"Chromed Racing Rings?"

[dancrabt]

I've been looking for piston rings and just got and e-mail back with $16.11 per ring for chromed cast iron rings. Is it worth the extra cost to buy them? And can you replace just the top ring with the chromed rings and use standard rings for the other two? They will be used in Merc modified outboards. And do chromed rings actually work better?

[Bill Van Steenwyk]

I have NO experience with them in a mod motor. That being said I tried them in both Flatheads and Konigs in the 70's. Once broken in they will run a LONG time if you have no other problems, but they take a long time to break in as they are a plated with or are Chrome which is very hard. If you want something to break in (seat) relatively quickly, they would not be my first choice for a racing engine, given the other problems you can have that require subsequent disassembly/reassembly of your engines.

For a pleasure engine that you want long life from they probably work very well, once broken in. The main problem is (at least my experience) they have a very long break in time, and if you don't do it right you have wasted your money.

There may be other issues as well, for example if you have to tear the engine down for another problem, repreparation of the cylinder walls before reassembly. I don't know about that, but with a softer ring it is very simple to run a ball hone in the cylinder and put new softer rings in. I do remember seeing the Bayers from Oklahoma using a very long, protracted break in process on their four cylinder merc's before a nationals one time, running them at a high idle in the water for quite a while, and then quite a few laps at slower speeds before running them full throttle. I don't know whether they were using Chrome rings or not. Perhaps Harry Brinkman's book has some information about this.

To carry the above reasoning a little further, which would you rather replace when it wore out, rings or sleeves? The harder material wears slower than the softer. Conversely the softer ring would seat quicker in the harder material, bringing maximum performance without a long break in period. You also mentioned the cost of the chrome ring. Which is more expensive, replacing the rings and honing, or boring the sleeves, new pistons and rings, etc., to maintain a straight bore and max performance. Either way it is expensive and time consuming to maintain max performance and that doesn't come without straight bores and good compression on all cylinders.

Harry ZAK always used softer rings than the bore in all my engines, for the reasons listed above. They were not MOD engines but did have iron sleeves, not the Nikisil prevalent today in a lot of engines, both race and pleasure.

[jeff55vDSH]

In my opinion, there is much more performance to be gained by switching to the newer 2 ring keystone style pistons and rings. :)