Piston suppliers are innovating product and improving processes while working overtime to keep orders filled and customers up to date.

With so many racing and performance enthusiasts working on projects during the pandemic, piston manufacturers have been busier than at any time in recent memory. While the resulting bottom line may be appealing to management, there are frustrating—and sometimes comical—moments for tech support representatives as the phone lines overflow with unusual requests and tedious (at times) problems to solve.

“Everything, I mean it’s tractors, airplanes, old boats, two-stroke motorcycles—it’s everything, dude,” groaned one rep who didn’t want his perspective to distract from the company’s products. “Since COVID hit, this industry is exploding.”

“It’s kind of crazy,” vented another. “Everything is coming out of the woodwork. I mean, guys are always trying to build some ridiculous thing. I don’t know where half this stuff comes from.”

The downside to all this fresh activity is that many of these resuscitated gearheads have forgotten the basics—and some never knew them in the first place!

“You’ve got everybody’s brother who should not be touching an engine,” the first rep continued, spilling his angst. “Then they’re screaming that the engine smokes and they want you to diagnose it over the phone in 20 minutes. These guys have no idea about piston-to-wall clearance, ring gaps, bearing clearances—and they’ve checked or measured nothing. They watch a YouTube video and believe they’re engine builders. They order .030-over pistons because the guy who sold them the block said it was .030-over when it’s really .038-over. They don’t check anything. It’s unbelievable! These people have never tried rebuilding a lawn-mower engine and now they’re diving into Ferraris and airplanes.”

Okay, support group sharing over—let’s talk about pistons and rings. The challenges of the past 12 months mostly kept this segment of the performance industry busy addressing new applications and keeping the shelves filled with product. While only a handful of companies actually introduced new lines, a number of suppliers continued expanding current applications, while others upgraded existing product with additional features.

Information about manufacturing technology and materials sourcing are generally closely guarded, yet we keep hearing hints of not only improvements in those directions, but also radical innovations that could become mainstream in the near future. Overall, it’s fair to say that strong sales are keeping the piston industry on a solid path of improvement, and OEM and racing technology advancements are enhancing the industry.

“We are adding 21 new numbers for 2021,” observed Brian Adix of Howards Cams, Oshkosh, Wisconsin.

“A lot of piston technology that was originally developed in pro classes is finding its way increasingly into sportsman racing,” added Jack McInnis of PBM-Erson, Louisville, Kentucky. “Weight-reducing innovations, including lighter forgings, shorter pistons, and shorter wrist pins enable higher rpm capability and increased power levels.”

“Surprisingly, the OEMs are more technologically advanced than a lot of race stuff that we do,” said Tony Calvert of CP-Carrillo, Irvine, California. “Granted, certain race teams with budgets will have some out-of-this-world stuff not found anywhere else. But within the trends we see throughout the racing community, the majority of customers are sorting by price and finding what matches their wallet. So, if you put in too much technology, suddenly it is out of what the majority wants to pay for it. We have to find a balance. We always want CP-Carrillo to be the highest technology that you can put in your engine. But at the same time, we also have to make it affordable.”

CP-Carrillo’s newest forging in the market is the SCBX piston for the Subaru EJ257. The boxed-strut underpinnings increase rigidity without loss of stress relief between the pin-boss towers. External struts are added at the edges to allow a 2.250-inch wrist pin, down from the original 2.500-inch to reduce weight. In what is likely an industry first for a shelf piston, the SCBX line will also provide an upgraded coated ring package.

“We’re also incorporating an anodized ring groove into these parts right off the shelf,” added Calvert. “The anodizing of the ring groove has always kind of been reserved for just custom parts due to the cost and the time involved to do it. But with extensive work in the OEM manufacturing that we have had for many years now with different auto and motorcycle manufacturers, it’s given us the technology and the expertise to be able to offer anodized ring grooves on off-the-shelf parts, which is something that no other piston supplier is doing right now.”

RaceTec Pistons in Huntington Beach, California, has introduced a new line of pistons to fill the gap between its budget-minded AutoTec line and the RaceTec racing series. Initial offerings will be for the small block Chevy, LS, small block Ford, and Gen III Hemi.

“It’s called AutoTec II,” explained Stacey Stone. “We took our existing AutoTec style forging and had it forged in 2618 material. These are designed for mild boost applications. We checked what we had to do as far as clearances and so forth. But it wasn’t like we had to reinvent the wheel. We already knew what we needed to do. We are not going to do any customs off this forging. It’s shelf parts only for the time being.”

The wide variety of aftermarket product for LS engines has prompted MAHLE Motorsport in Fletcher, North Carolina, to design a piston that works with more than one cylinder head.

“The LSX Combo that has a valve-pocket geometry can fit multiple LS cylinder heads,” said Joe Maylish, also noting the company is introducing new or upgraded pistons for the 23-degree SBC, Kaase Boss Nine and 5.7 Hemi-stroker applications. “I think it’s an advantage for racers. We design that LSX Combo line with a 2618 alloy, so it is for high-horsepower applications that are going to involve boost and power adders. So it is definitely focused toward the racer that is working with some different head combinations or wants to try some different things. It makes it more user-friendly. It will come with a 1-mm, 1-mm, 2-mm ring pack and a .927-inch pin.”

Requests are also picking up for BMW pistons, with nine new offerings released in the past two years. Road racers using the twin-turbo N54 six-cylinder are especially eager to replace pistons. “That one really stands out,” Maylish added. “It comes in a 2618 alloy and a 17.2cc dish or a 21.5cc dish.”

JE Pistons in Cypress, California, scored a big breakthrough a couple of years ago with the release of the Ultra Series Forging, which featured an aligned grain flow to reduce weight while improving strength. Now the company is expanding the product applications and building new forgings to fit a larger range of engines.

“Our Ultra Series Forgings are the only pistons in the industry with aligned grain flow,” said Nick DiBlasi, noting that it took years of trial and error to develop the manufacturing process. “Aligning the grains by a multi-step forging and heat-treating process allows for a stronger grain structure when forged into the piston shape. We see a 20% strength increase when compared to like non-aligned forgings.

“Racers had a fixed weight we needed to meet, yet it needed to handle more power than what was available,” he continued. “In some applications racers would only get 10 passes from traditional forged 2618, and now they are able to run an entire season of racing.”

New crate motors that are stimulating the market are also drawing interest from piston manufacturers. Ford recently introduced a 430-horsepower, 7.3-liter V8 crate engine. Nicknamed “Godzilla,” the engine comes with cast pistons. A leading customer of Ross Racing Pistons is currently dyno’ing the engine to find areas of improvement and also test its failure limits. He sent a cylinder head to the company’s El Segundo, California, shop so Ross could design the crown.

“We digitized the cylinder head and expect him to call us with information needed to build a piston,” said Chris Madsen from Ross. “We will make the piston strong enough to where they can really lean on it and find out how good this motor is. He’s just trying to get ahead of the game so he can sell rotating assemblies.”

Initial plans call for bumping the compression ratio to help “wake up” the engine, and moving to a metric ring set in the range of 1.2, 1.2, 3 mm with a 14- or 15-pound oil ring.

On the manufacturing side, innovations in forging technology are moving forward, too. At Performance Forge in Montebello, California, modular tooling is helping to reduce costs.

“Without giving away too many trade secrets, it gives us the opportunity to repair a piston punch tool because it’s modular. When a one-piece piston punch starts to break, in some cases it pretty much becomes unsalvageable. We’re able to take modular tooling apart and get to the difficult areas,” explained Wayne Ramay. “We’ve also learned a significant amount about how to build these tools and what materials to use to increase their longevity.”

During the technology’s development, one of the proposed benefits was the flexibility of changing design features more quickly, such as altering just the crown tooling to produce pistons with different compression ratios.

“I thought that was going to be a significant advantage for some of the piston designers to be able to do that. I have not been able to convince any of them that it makes sense for them,” Ramay said. “Technically, it’s still a capability we could do—take the centerpiece out and put a different one in. But nobody has actually taken me up on that.”

Performance Forge also acquired a second infrared oven that heats up the aluminum slugs faster, which improves the forging strength. “The objective is smaller grain size,” Ramay explained. “Without getting too technical, the longer aluminum is exposed to high temperatures, the larger the grains grow, and large grains are not conducive to strength. And so, what used to take me two hours to heat up a piece of aluminum before I could forge it is now 20 minutes with this new oven.”

UEM-Icon/KB Pistons in Carson City, Nevada, is also upgrading its manufacturing processes with a newer way to apply anti-friction coatings. “The process used to be wash them and then apply an anti-scuffing material,” said Marko Glush. “Nowadays, it’s quite complicated and labor intensive. There are different cleansing baths and etching. And also, the coating materials themselves last much longer compared to earlier coatings. And, the new coatings are much safer. The early ones were quite hazardous.”

The company is also seeing a growth spurt in its diesel line. “That market is booming right now, and those guys are running crazy boost numbers,” said Glush. “What they’re finding is that the loads on the ring lands are so severe.”

UEM pioneered the practice of bonding iron inserts into the top ring land of cast aluminum pistons in the 1950s, according to Glush, and now the company has revived that process for its Dualoy line.

“It’s the most challenging piston to make because of that iron insert. It’s very labor intensive and goes through a lot of quality control testing that alpha bond. It has to be 100% or the pistons will separate,” Glush added.

Future Expectations

For the immediate future, don’t expect new materials or designs to dominate the headlines. Manufacturers are generally pleased with their alloy suppliers, both 2618 and 4032, but always on the prowl for improvement. 

“We are constantly testing different aluminum alloys for the best strength, longevity, and cost,” said JE’s DiBlasi. “There are many available materials that are very good, however the cost is prohibitive for the general public. Something around 10 times the material cost and roughly five times more difficult to machine.”

The boxed-strut design will continue to be refined as piston makers strive for the perfect balance between weight savings and strength. And speaking of balance, a new buzzword that’s circulating around more shops nowadays is “dynamic balancing.”

“That’s trying to get the piston balanced on the wrist pin,” explained Madsen. “It’s mostly meant to work with conventional big block Chevrolet cylinder heads. Those pistons have a tendency to want to push to the one side just because of the size of the dome. Some of these domes are .800-inch tall. That’s a lot of weight on one side of the piston and then under the combustion. So, it wants to push that dome, and they have a tendency to scuff on one side.”

Yet another glimpse into the future is coming by way of additive manufacturing or 3D printing. Long used by the aftermarket to print plastic prototype pieces for testing and fitment, 3D printing is now advanced to the point where a number of metallic parts are produced. The process has already shown promise in developing exhaust and cooling products, because very unique and efficient flow paths can be designed. However, with pistons the benefits have yet to be revealed for most types of racing.

“It’s finding the right niche where it’s needed, and that’s still an evolving process,” Calvert said. “The technology we have so far into forging and heat-treating has come so far that the 3D printing way of getting to that same point has to start at ground zero and catch up to even get close to the productivity, strength, weight savings, durability, and just the trustworthiness of the formula that’s already working great.”

RINGS OF DESIRE

Within the past couple of years, perhaps the most important design innovation on any part of the reciprocating assembly has been Total Seal’s gas-ported ring.

“We are doing gas-ported top rings and gas-port second rings,” said Keith Jones of the Phoenix, Arizona-based piston ring manufacturer. “I’m even doing gas-ported Dykes-style rings—which are very common in blown alcohol and turbo cars. There has not been a single test run where there has been a loss of power. It’s always better.”

Of course, piston manufacturers have long offered vertical gas ports on the pistons, but Jones said if they’re not properly placed there can be reversion around the rings.

“That creates a lot of issues on the intake stroke if the rings do not seal properly,” he noted. “By putting the gas ports in the ring, they’re always in the right spot. The other thing, the rings rotate. With the gas-ported piston, especially in alcohol motors where you run a lot of fuel, you will see very high wear lines in the bore. When you look at these, you will see that they lined up with the gas ports. You have these high-pressure points. By putting the gas port in the ring, the ring rotates and you’re getting uniform, even pressure load all around the cylinder.”

Total Seal continues to test different configurations involving the port size, locations and numbers. “We have multiple combinations of sizes, quantity, depth—all depending on the size of the ring. There is a method to the madness,” Jones added.

Piston companies are still offering both vertical and lateral gas ports to customers in addition to suggesting different sizes.

“Ring selection is very much rpm and compression driven. At 9,000 rpm, 1-mm or .7-mm top rings are required along with lateral gas ports. When using nitrous or boost, a steel top ring is preferred, not ductile,” said Jack McInnis of PBM-Erson, Louisville, Kentucky. “Lighter ring packs like the 1-mm and .7-mm top ring sets mean that piston stability is much more critical in order to maintain good ring seal and wear characteristics. This requires a higher degree of precision in manufacturing and measuring equipment to maintain even closer tolerances.”

Meantime, the team at JE Pistons in Cypress, California, is testing new materials and coatings that are “allowing for very high-horsepower numbers with relatively thin rings,” Nick DiBlasi told us. “It was common for many of the blown alcohol engines to use Dykes-style rings, which were almost 2-mm thick. With better material you can handle the same or more power with a 1.5-mm to .064-inch ring.” —Mike Magda

SOURCES
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Arias Pistons
ariaspistons.com

CP-Carrillo
cp-carrillo.com

Howards Cams
howardscams.com

JE Pistons
jepistons.com

MAHLE Motorsport
mahlemotorsports.com

Manley Performance Products
manleyperformance.com

PBM-Erson
pbm-erson.com

Performance Forge
performance-forge.com

PROFORM
proformparts.com

RaceTec Pistons
racetecpistons.com

Ross Racing Pistons
rosspistons.com

Summit Racing Equipment
summitracing.com

Topline Automotive
toplineauto.com

Total Seal
totalseal.com

Trick Flow Specialties
summitracing.com

UEM-Icon/KB Pistons
uempistons.com

Wiseco Performance Products
wiseco.com