The Evolution of Piston Rings and the Science of Honing

We all know that technology is advancing at an incredibly fast pace. So, it stands to reason that any area where the technology can be applied will experience a similar significant advancement. This is the subject of Episode 163 of Epartrade’s Race Industry Now webinar series. In this hour-long technical conference, Lake Speed, Jr. and Keith Jones of Total Seal are joined by Ed Kiebler of Rottler Manufacturing to discuss what has changed and why in piston ring design and engine technology. cylinder machining.

It goes without saying that the two companies work closely together, because the topics go hand in hand. Good piston rings only improve with the right cylinder finish, and the right cylinder finish can make an OK ring pack even better. So, thanks to extensive research and development, we find ourselves at a point in history where both components are better than ever, and the end user is reaping the rewards, with levels of performance only dreamed of in past years.

measuring success

When looking for advancements in piston ring and cylinder wall technology, there are several criteria to measure – the horsepower (through increased sealing) and the longevity of that horsepower.
“Even going back to 2000, NASCAR teams expected racing with an engine,” says Lake Speed, Jr. of Total Seal. “Not a race weekend – a race. They had a qualifying engine, a practice engine and a race engine. All because you couldn’t risk putting more miles on the engine, since we We all knew that by the end of the race, the engines would be down five to ten horsepower or more.

In the case of NASCAR engines, attempts at improvement were obviously aimed at increasing power, but making it last for an entire 500-mile race. “These days, [NASCAR engines] make more power – at least before they are limited – and live three or four times longer. They can run an entire race without running out of power. Even being in power in some cases, since they were brand new,” says Speed. “We still see people doing what was done then, today. Does it work ? Sure; He won races. There’s so much more out there now. And that’s really what we want to draw the curtain on.

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

ring technology

Over the past 20 years, many advancements have been made in piston ring technology. Both in terms of the materials from which the rings are made and the coatings applied to them, in post-production. These material advances have made piston rings much thinner while providing not only better sealing but also longevity in their given applications.

“I had a conversation with an old school Pro Stock rider who was looking for a set of 0.8mm/0.8mm/2.0mm rings. Not for a Pro-Stock engine, but just for a high-performance big-block Chevy. He said to me, “I can’t believe someone still uses 1/16 inch, 1/16 inch, 3/16 inch rings… What’s wrong? with these people?” says Keith Jones, director of Total Seal. technical sales.

“Really, there’s nothing wrong with them, they’re 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 stick with it. We have people who spend tens of thousands of dollars on the finest cylinder heads and the coolest manifolds, and yet there are 20 horsepower sitting in their ring pack. They just have to be willing to try something different.

Modern advancements in materials science have enabled incredible advancements in the science of piston rings. These Ndurance oil control rings are the latest offering from Total Seal and have more advanced technology than their relatively simple appearance would suggest.

Build a better wall

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

To that end, Rottler Manufacturing has devoted significant resources to creating a better cylinder wall finish for the impressive new rings under development. If you look at the numbers that come out of their current range, it looks like they got it. “We’ve taken a new style of break-in with our new machines,” says Rottler’s Ed Kiebler.

“I’m getting customers seeing up to 20 horsepower gain on their engines, just by changing the break-in process — not even changing the rings at all. If someone can take 20 horsepower with new rings, and let’s be careful and say 10 more horsepower through a new break-in process, there’s 30 horsepower right there. That’s pretty important in any form of racing.”

As Jones mentioned, to take advantage of new processes and their inherent benefits, people need to be able to step out of their comfort zone. “We’re not saying the way people are doing it now is wrong. The old ways are OK and they still work, but there are better ways to do it now. The new process with diamonds and CBN (Cubic Boron Nitride) really seems to make a difference in engine tightness and the resulting power increases.

Much like piston rings, advances in materials science have improved all forms of abrasive machining, especially the use of industrial diamond and cubic boron nitride abrasives.

“[In the new process,] we switched to a diamond abrasive as a base finish, then we go beyond that with a CBN abrasive. It’s a very sharp particle and it cuts a very clean finish, giving you a lot less ripped and chipped metal in the surface finish,” says Kiebler.

cylinder lapping

Advances in abrasive technology have not only allowed immensely greater control over the surface finish, but also over the overall roundness of the bore. Both are key elements in horse production.

“The reason we use diamond abrasives is because it is one of the hardest particles known to man. But, believe it or not, we use it economically. A quick ballpark figure is that with standard abrasive, removing 0.003 inches on eight cylinders will cost you between $1.80 and $2.50 per block. Using diamond abrasives in this same process will cost you a nickel per block. They are more expensive to buy, initially, but will last forever in comparison – 60,000 to 80,000 bores.

Along with the benefits of the materials themselves, the materials allowed Rottler to redesign some of its tools, to go beyond a direct replacement for old-fashioned honing stones. “We are now able to put more abrasives in a lapping head. With the old models, we had two abrasives and two wipers. Now we have found that the more abrasives in a lapping head, the rounder the bore will be.

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

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