“Keep it simple.” We’ve all heard that expression and welcomed the peace of mind it suggests. But for engine builders, the idea of keeping it simple can be quickly blown out by the enormous array of combinations available.
The GM LS series of engines is no different in that regard. Figuring out the right parts to buy for this popular platform’s numerous variants can be complicated. While the factory did an admirable job of limiting stroke lengths and compression heights, once you get into aftermarket stroke and rod-length combinations along with the variety of cylinder heads and countless combinations of power adders, fuels, and applications, you have the potential for a mind-melting number of piston choices.
But MAHLE Motorsport has developed a series of pistons that helps solve some of these problems. The company’s LSX Combo line simplifies choosing and stocking LS-engine pistons, with specially engineered designs that work on several types of LS engines and cylinder heads. the valve reliefs designed to fit multiple valve geometries promise to bring an element of ease to LS engine piston selection, while significantly reducing the number of parts engine builders need to stock.
To learn more about these pistons, we spoke to Joe Maylish, marketing program manager at MAHLE Motorsport. This division of MAHLE International was created in 2000 to develop pistons for NASCAR teams, and continues to do so for them, along with a wide array of other motorsports, including drag, circle track, and endurance racing.
But not everyone in the racing world knows who MAHLE Motorsport is. “We always seem to get confused with MAHLE Aftermarket,” says Maylish. “We do share a booth at the PRI Show, but we’re completely different entities when it comes to products. MAHLE Motorsport focuses solely on high-performance forged pistons for motorsports applications.”
MAHLE Motorsport engineers began developing the LSX Combo line in 2016, after a series of conversations showed the need to offer a universal piston solution for LS engines. “In talking with engine builders, they kept saying they wished they had something that could fit all of these different combinations,” says Maylish. “We realized that if we were able to take our LS pistons and develop them into this concept, everyone could definitely save on inventory.”
After the earliest days of the pandemic, it was the summertime, and people started buying everything like crazy. We had exhausted our stock of other forged pistons, so we started turning guys onto the LSX Combo piston. — Joe Maylish, Mahle Motorsport
From there, the team began to consider what specific piston designs should be offered. Although the need to satisfy a wide range of applications was vital, ultimately it came down to balancing those needs with the potential for a reasonable sales volume. “The best marketing out there is real-world,” says Maylish. “It comes from the engineers and engine builders doing their work, and then seeing what moves sales-wise. So we looked at sales in the different areas of LS and what made sense.”
But despite laying this strong groundwork, sales of the LSX Combo line got off to a slow start when it was introduced in early 2020 — the pandemic was putting a damper on demand for just about everything, including engine parts. But, like a see-saw bouncing back to the upswing, the side effects of this international crisis ultimately breathed new life into the line. “After the earliest days of the pandemic, it was the summertime, and people started buying everything like crazy,” says Maylish. “We had exhausted our stock of other forged pistons, so we started turning guys onto the LSX Combo piston.”
Now that many engine builders have seen firsthand the advantage of the LSX Combo series, sales of the line are strong and its reputation continues to grow, vindicating this one-size-fits-many approach to piston design.
How it Works
To accommodate multiple engine and cylinder-head configurations with one piston design, the valve pockets on MAHLE’s LSX Combo line are shaped to fit several LS cylinder head types. So, for example, where there would typically be three different piston-dome variations for a particular compression height on LS1, LS92, and LS7 engines, Mahle’s LSX Combo line instead covers them with just one part number.
Although this might imply some compromises in terms of compression ratio, dome shape, and valve clearances, the differences don’t add up that way, according to MAHLE. “There isn’t really a disadvantage,” says Maylish. “The compression ratio is calculated at zero deck with a .040-inch gasket. So there are always ways that engine builders can gain back some of that compression ratio if needed.”
“And builders love this approach once they discover it,” continues Maylish. “Pretty much every day, we get people calling us saying, ‘Do you have something that fits this, and will it work with this?’ Then we show them the Combo pistons, and they say, ‘This is awesome. I didn’t even know this was out there.’”
Besides making piston selection more straightforward, LSX Combo pistons reduce the number of different part numbers that shops have to keep in stock to satisfy customers. “Imagine only needing one set of pistons in stock for a 4.125-inch bore-size LS,” says Maylish. “Then, no matter who comes through the door, if they have that bore size, there it is — you have it on your shelf without having to carry three sets of pistons.”
LSX Combo pistons can also help ease the woes of today’s all-too-common supply-chain issues. “If you’re an engine builder, you’ve got to keep stock on your shelf,” says Maylish. “But you’re going through these situations where you’ve still got to pay your guys who work for you, and you’re spending hours on the phone trying to find parts. So, if you can take your inventory, and reduce it from having three parts on the shelf, that frees up a lot of time and money.”
The Right Stuff
MAHLE Motorsport’s LSX Combo pistons fit LS1, LS2, LS6, and LS7, with LS3 and LS92 heads. They’re available in flat-top, dome, and dish configurations, and are offered in both 4032 and 2618 alloys. “With 4032, the piston-to-wall clearance will be tighter,” says Maylish. “And because it’s going to be a little bit tighter, on initial startup it won’t have as much noise if it’s really cold. The 2618 alloy is meant to be used with high-horsepower applications. They can be turbocharged or boosted, but you can also take 2618 and use it in a naturally-aspirated setup too.” MAHLE can also customize any LSX Combo pistons to accommodate unique needs that aren’t covered by standard part numbers.
Another advantage of LSX Combo pistons is that they’re sold in convenient, complete sets, which MAHLE calls their PowerPak line. These sets include pistons, high-strength steel pins, clips, and file-fit rings. “It all comes in one box to make it easy for the builder,” says Maylish. “You don’t have to run around sourcing rings. They come with it. And they’ll work for whatever you’re doing. If you’re doing a naturally-aspirated build, set your ring gaps for that. If you’re doing a build that will involve nitrous, set your gaps for that. It’s really versatile and friendly for the engine builder.”
LSX Combo PowerPak sets are available through engine builders, independent performance-parts shops, and major online retailers, just like all of MAHLE’s pistons. Although MAHLE Motorsport currently offers Combo pistons only for LS engines, PowerPak sets are available for most popular V8s, including Chevy, Ford, Mopar, Oldsmobile, and Pontiac, as well as a wide range of other engines.
And if you aren’t completely sure of what pistons you need, or have questions about the new multiple valve geometry pistons, MAHLE encourages you to call and talk to one of their tech specialists. “We live in a world where people want to find the answer on Google,” says Maylish. “But because there are so many ways to build a motor and so many different applications out there, it really should involve a conversation. Give us a call, tell us what your build is going to be, and we can have that conversation.”