Camshaft And Valvetrain Technology Insight - On The Lobe's Edge

Speaking of LSx cams, Comp's lineup has been vastly expanded. "Some of our bestselling LS cams were custom grinds," Godbold confided in us. "So it was time to step up and take care of business. It's hard to know where to start. Right off the bat, Comp has expanded its old-school sounding Thumpr series into the LS arena-ground with a 109-degree lobe separation angle, these 'sticks are designed to work with both retuned EFI and carbureted LS engines. And although the idea was to create a cam for drivers who are more worried about sound than power, the LS Thumpr's advanced intake lobe and long exhaust duration have other benefits: "With the small inlet and the big-like-a-road-race-car exhaust, they're not bad for SCCA autocross. If you want something that will shred tires and sound nasty, this is the one.

Then again, the Thumpr is just the tip of Comp's new line LSR offerings. "Some new LS heads almost flow what '90s NASCAR heads flowed," Godbold said. As a result, Comp has come up with 35-plus new part numbers "so everybody will have a cam customized for their engine without having to search message boards for todays magic custom grind," he says.

The variations are extensive. There are three subfamilies for LS Cathedral Port heads, versions for 4.8L and 5.3L engines, "all-out power versions" for 5.7L and 6.2L mills, and large-displacement variations for 6.2L and 7.4L engines. Not enough for your? Comp also developed cams for the newer rectangular-port heads for large-displacement engines (6.2L-7.4L) and all-out power apps (5.7L-6.2L). If that's still not enough, new grinds are on the way for centrifugal blowers, Roots blowers, and remote-mount turbo apps. "The new LSR cams are the quickest, more powerful, largest-area cams that Comp has ever introduced for street/strip hydraulic roller applications to date," said Godbold. Comp also designed a spring around this application. These parts are working towards a common goal...synergy in these engines with great power and valvetrain stability over 7,000 rpm.

Godbold took enough of a breath to tell us about one really trick piece for traditional small-blocks: the new Ultra-Pro Magnum Rocker Arms. "It's an arch design, he told us, a throwback to the Roman arch and webbing, and there's no better way to make something." It decreases the moment of inertia, or resistance to rotation. "We didn't just focus on the rocker body's overall mass. We focused on what really matters. Inertia is much more important," Godbold explained. We couldn't help but ask, why create a new Pro Magnum rocker, given the popularity of the existing one? "We know how to build a better rocker," he said, "The design is 20 years old, and the tooling could be replaced. We figured, why not knock it out of the park? Let's do the best Pro Magnum we can."

There's certainly a key to this technology explosion, and Godbold elaborated on it. "The difference between two years ago and today," he began, "is that we can design a system on a computer. Before, we would make a part, and 10 design variations might take four to five years. It's all about the software and being able to use it. When it comes to getting an idea of what's best for a package, we can answer these questions now. On cams, there's a lot of things we couldn't do before. We used to talk about designing a cam at the valve, but because of technological limitation, we had to design at the cam, then had to factor in the rocker arm. We can now design at the valve and factor back. We're getting newer toys, and better pieces to build. Now is the most exciting time to be in valvetrain design.... We're so much better at modeling and measurement. If we didn't have good measurement, we wouldn't have good models. You have to get the model dialed in, and the more accurate model has more inputs. It really speeds up development."