Epartrade Webinar: The Evolution of Piston Rings And Honing Science

Epartrade Webinar: The Evolution of Piston Rings And Honing Science

We all know that technology is advancing at an incredibly rapid pace. So, it only stands to reason that any field where technology can be applied will experience a similar significant advancement. Such is the topic of episode 163 of Epartrade’s Race Industry Now webinar series. In this hour-long tech-talk, Total Seal’s Lake Speed, Jr. and Keith Jones are joined by Rottler Manufacturing’s Ed Kiebler to discuss what has changed and why in the designs of piston rings and cylinder machining technology.

It only stands to reason to have the two companies working closely together, as the subjects go hand-in-hand. Great piston rings are only made better with the right cylinder finish, and the right cylinder finish can make an OK ring pack work even better. So, through a lot of research and development, we are sitting at a point in history where both components are better than ever before, and the end-user is reaping the rewards, with levels of performance only dreamt of in years past.

Measuring Success

When looking for advancements in piston ring and cylinder wall technology, there are multiple yardsticks to measure by — horsepower (from increased sealing) and longevity of that horsepower.
“Even going back 2000, NASCAR teams expected one race out of a motor,” explains Total Seal’s Lake Speed, Jr. “Not one race weekend — one race. They had a qualifying motor, a practice motor, and a race motor. All because you couldn’t risk putting more miles on the engine, since we all knew at the end of the race, the engines would be down five to ten horsepower or more.”

In the case of NASCAR engines, the attempts to improve were obviously to make more power, but to get it to last for an entire 500-mile race. “These days, [NASCAR engines] make more power — at least before they were restricted — and live three or four times longer. They can run an entire race without being down on power. Even being up in power in some cases, from when they were brand new,” says Speed. “We still see people doing what was done back then, today. Does that work? Of course; It won races. There is so much more out there now. And that’s really what we want to pull back the curtain on.”

With the proliferation of precision metrology tools, like the Mitutoyo profilometer shown here, not only are we able to accurately measure our finishes, but properly develop strategies around those measurements.

Ring Technology

Over the last 20 years, there have been a lot of advancements made in piston ring technology. Both in the materials, the rings are made from as well as the coatings applied to them, post-production. These material advancements have allowed piston rings to be made much thinner while not only providing a better seal, but having plenty of longevity in their given applications.

“I had a conversation with an old-school Pro Stock racer who was looking for a 0.8mm/0.8mm/2.0mm ring package. Not for a Pro-Stock engine, but just a great-performing big-block Chevy. He said to me, ‘I can’t believe anyone is still running a 1/16-inch, 1/16-inch, 3/16-inch rings… What’s wrong with these people?’” says Keith Jones, Total Seal’s Director of Technical Sales.

“Really, there’s nothing wrong with them, they are just in a comfort zone with a recipe they’ve been using since 1975, and it’s never backfired, never bit them, and it works, so they are sticking with it. We have people spending tens of thousands of dollars on the trickest cylinder heads and the coolest manifolds, and yet there’s 20 horsepower sitting in their ring pack. They just have to be willing to try something different.”

nDurance piston rings

Modern advancements in material science have allowed for some incredible advancements in piston ring science. These Ndurance oil control rings are the latest offering from Total Seal and have more advanced technology in them than their relatively simple appearance would suggest.

Building A Better Wall

If you can build a better piston ring using modern technology, it only stands to reason that you can build a better surface finish on the cylinder wall as well. “It’s not just the piston rings by themselves, it’s the piston ring interacting with the cylinder wall,” says Speed, describing his “Ring Seal Soup.” “It’s the surface finish of the wall, the ring material, the ring finish, and the oil all having to work together.”

To that end, Rottler Manufacturing has been devoting significant resources to creating a better cylinder wall finish for the awesome new rings being developed. If you look at the numbers coming out of their current lineup, it appears they’ve figured it out. “We’ve been doing a new style of honing with our new machines,” says Rottler’s Ed Kiebler.

“I’m getting customers seeing up to 20 horsepower gains on their engines, just by changing the honing process — not even changing the rings at all. If someone can pick up 20 horsepower with new rings, and let’s be conservative and say another 10 horsepower through a new honing process, there’s 30 horsepower right there. That’s pretty big in any form of racing”

As was alluded to by Jones, in order to take advantage of the new processes and their inherent benefits, people have to be able to step out of their comfort zone. “We’re not saying that how people are doing it now is wrong. The older methods are OK and they still work, but there are better ways of doing it now. The new process with diamonds and CBN (Cubic Boron Nitride) really does seem to make a difference in sealing the motor and subsequent horsepower increases.”

Just like the piston rings, advancements in material science have allowed improvements in all forms of abrasive machining, particularly the use of industrial diamond and Cubic Boron Nitride abrasives.

“[In the new process,] we’ve gone to a diamond abrasive as our base finish, and then are going over the top of that with a CBN abrasive. It’s a very sharp particle and it cuts a very clean finish, giving you a lot less torn and fragmented metal in the surface finish,” explains Kiebler.

cylinder honing

Advancements in abrasive’s technology have not only allowed for immensely more control over the surface finish, but also the overall roundness of the bore. Both are key components in making horsepower.

“The reason we use diamond abrasives is that it’s one of the hardest particles known to man. But, believe it or not, we use it from an economical standpoint. A quick ballpark figure, is with a standard abrasive, taking .003-inch out of eight cylinders will cost you anywhere from $1.80 to $2.50 a block. Using diamond abrasives in that same process will cost you a nickel a block. They are more expensive to purchase, initially, but they will last forever by comparison – 60,000 to 80,000 bores.”

Besides the benefits of the materials themselves, the materials have allowed Rottler to redesign some of its tooling, to go beyond direct replacement of the old-school honing stones. “We are now able to put more abrasives in a honing head. With the old designs, we used to have two abrasives and two wipers. Now, we’ve found that the more abrasives that are in a honing head, the rounder the bore is going to be.”

Believe it or not, that only covers the first quarter of the Epartrade webinar linked above. So if you’ve read this far, you are probably interested in the topic, so we suggest you watch the video in its entirety. You’ll walk away with a much better understanding of where the sciences of piston ring design and honing technology are today.

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About the author

Greg Acosta

Greg has spent seventeen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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