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When it comes to any video with Total Seal‘s Lake Speed Jr. in it, you know you’re about to learn something. When Speed appears next to someone like Dr. Peter Lee, Institute Engineer and Chief Tribologist at Southwest Research Institute, you KNOW there is some serious knowledge transfer about to occur. In this video, the duo discuss the subject of friction and wear, and explain things in a manner that, at first glance, seems to go against conventional thinking.
Southwest Research Institute (SwRI) is an independent research laboratory that conducts research and development testing for clients across the gamut of technical disciplines. Specific to involving Lake Speed and Total Seal, SwRI does a lot of friction and wear testing of piston rings, cylinder material, and, of course, engine oil. By sectioning a cylinder liner and a piston ring, the components are assembled in a test rig in SwRI’s lab, where both friction and wear can be accurately measured as the parts reciprocate.
In addition to being able to directly measure friction and wear, Speed points out another avenue of analysis. “Since it’s running in a bath of oil, we can also take a sample of the used oil and analyze it.” Using Inductively Coupled Plasma (ICP) testing, the used oil can be broken down into its constituent molecules and analyzed to determine how many parts per million of various substances are in the oil, that there shouldn’t be. Likely, you’ve heard of oil analysis through Speed’s company, SPEEDiagnostix, but in this laboratory setting, there are far fewer contaminants than when analyzing oil that has gone entirely through an engine.
As you can see, each test sample was thoroughly cataloged. The coarse-honed cylinder was a 325-400 grit diamond finish. The fine cylinder was a 170-200 grit base hone, followed by a 600-grit plateau finish for less friction between the ring and wall.
How Can Friction And Wear Not Interrelate?
“We took two different surfaces — one was a rough hone and one was a smoother hone — and ran the same oil and the same ring,” explains Speed. “Then we switched rings on both of the liners while keeping the oil the same,” Lee adds. “And then to confuse things even further, we changed the oil.” By changing the chemistry of the oil, Speed hoped to improve the results of the testing, but the test results provided some interesting data points.
“We’ll call it a general trend, but going from an uncoated ring to a coated ring, we saw wear go down. When we coupled the ring coating with the improved oil chemistry, the wear went way down. Starting with the rougher finish (325-400 grit diamond) we started with 83ppm of iron down to 50ppm with the coated ring. That’s just changing the ring coating,” says Speed. From there, the new oil chemistry was added, and iron particulates dropped 34 percent to 33ppm.
Here you can see the wear results (in parts-per-million of iron) from the three coarse tests. On the left is a bare ring with the baseline oil chemistry. The middle is a coated ring with the same oil. On the right is with a coated ring and an improved oil chemistry.
Moving to the less-coarse hone, which, by all accounts should account for less friction than a rougher hone (and ostensibly, less wear, according to current logic) the tests were started over. “With the bare ring and the first oil, we saw 120ppm [of iron]. It really didn’t like that one,” says Speed. Adding the coating to the ring dropped wear significantly — on the order of 66 percent less wear to the ring in the same test. “That one was really surprising,” Lee and Speed agreed. Then, adding the improved-chemistry oil, wear dropped another 50 percent to only 20ppm. “It’s incredible that we can go from a high of 120ppm all the way to 20ppm just by changing components,” says Speed. “What’s really neat about all of this controlled testing is being able to isolate all of the variables.”
The friction between the cylinder wall and the piston ring wasn’t assumed. SwRI thoroughly measured the friction occurring in each test.
From these tests, we find that friction can be decreased, but wear increases (as evidenced by the smoother cylinder having more wear) and that friction can be increased, but offer reduced wear. Of course, this has been known for a while, through the use of zinc in oils. “ZDDP does a fantastic job of reducing wear, but it increases friction,” says Speed. “When you get everything right, you will reduce friction and wear, together.”
By this point, you might be asking yourself why friction matters if you can decrease wear. The answer is simple: efficiency. Besides reducing temperatures, since friction causes heat as lost energy, reducing friction also increases power. We’ve known for a long time that if you reduce friction you increase horsepower, so ideally, you want to reduce both friction and wear in order to have a more efficient, longer-lasting engine.
Here are the results of the finer bore testing. The uncoated ring and base oil (left) had an incredibly high amount of wear — even more than the higher-friction cylinder finish. Once a coated ring was introduced (center) wear fell off significantly. On the right, you can see with the addition of a modified-chemistry oil, the combination really shined.
More Answers Lead To More Questions
“These six tests only represent a small portion of testing,” says Lee. “Every one of these results leads to more questions. We’re testing different viscosities and different coatings on the rings. In theory, if we change the coating on the ring, the current oil chemistry might not be compatible with it.” Speed reveals that it’s not just hypothetical and that they have absolutely found oil chemistries and coatings that don’t get along well together. “We’ve had some tests where the coating has come off. And when that happens, really bad things start to happen.”
This isn’t the end of the testing by a long shot. In fact, Speed is excited because, not only will the variables continue to change, but so will the method of analysis. “EDX is Energy-Dispersive X-Ray spectroscopy and it goes in and looks really closely at what’s on the surface at an atomic level,” Lee explains. “You can see if there are bits of carbon on the surface. You can see how the actual honing looks right down at a very granular level. And after that, you can see what chemical film has been put down where the ring is running.”
The quest for the most efficient engine seems to be never-ending. As soon as we find a new best thing, there is tireless work happening in the background to make something better. The max-effort engines of today are leaps and bounds more efficient and longer-lasting than those of even 20 years ago, thanks largely to this kind of testing. And lucky for us, we’re getting a peek behind the curtain to see how these improvements are being made.
This is a 3D rendering of the wear trace on each of the samples. The amount of data gathered by SwRI in this type of testing is absolutely incredible. And to think all this effort is being devoted to simply improving engine performance.
