Earlier this year, we brought you a thorough, in-depth, scientific explanation of Comp Cams’ new Low Shock Technology camshaft lobe designs. While it’s hard to top that kind of explanation, that deep-dive into the nitty-gritty of the technology can be outside the comfort zone of some.
Luckily, while COMP Cams’ Billy Godbold might be a legitimate nuclear physicist he also has a Ph.D. in hot-rodding and knows how to speak to enthusiasts. That ability, combined with some cool, easy-to-understand animations, make this explanation of the LST philosophy — and make no mistake, this is a change in fundamental thinking in cam-lobe design — one that anyone can understand.
“In layman’s terms, COMP’s Low Shock Technology is a way we design a camshaft profile to load the system slightly before we accelerate the valve off the seat,” Godbold starts out. “The idea behind that is to not shock the spring and not create bad harmonics, to allow us to do more throughout the range of valve motion.”
Arriving at the Right Conclusion
While innovations in modern valvespring technology have assisted in the development of Comp’s Low Shock Technology, the basic premise of the Low Shock design was known to work, even if they weren’t 100-percent sure why it worked.
“Famous racers would take a camshaft, and if it accidentally got ground with the cam master on backward, sometimes that would run better,” says Godbold. “Those camshafts had something like today’s Low Shock Technology. We’ve gone back and reinvestigated what we were doing in the 1980s and ‘90s and trying to come up with a really sophisticated way of loading the valvetrain before we aggressively accelerated off the seat.”
Part of the reason for the advancement in understanding is thanks to advances in both computational modeling and diagnostic tools. “We’re able to take what we’ve learned from the Spintron, and really optimize where the ramp needs to be slow, and where in the ramp it can be extremely fast,” Godbold explains.
“If you think about a pole vaulter running up, jamming his pole into the pit, and then vaulting up over the bar, that’s how old cam designs worked. We used to think the more you could squeeze the bottom of a lobe, the more we could expand the top of the lobe, the more power we could get. That generally worked. What we’re learning now is, it’s not both sides that do this equally. The closing side really needs that area and that squeezing.”
The opening event, on the other hand, responds far better to a gentle scooping to initiate valve motion as opposed to being slammed into an aggressive ramp. “What we’re learning how to do, is take care of our valvespring on the opening side, to be able to maximize the area once we build up airspeed and start filling the cylinder,” says Godbold.
“Whether you’re racing NHRA Top Fuel, or a Pro Mod, or a turbo outlaw car — no matter what the application — there are no performance drawbacks to slowly opening the valve at the very beginning of the motion. The reason being is, near top dead center, There is almost no air going from the exhaust to the intake. What we’re really trying to do is create a pressure wave to initiate that airflow movement.”
A Low-Pressure Front Leads to Snow
To explain the concept of how small airflow turns into big airflow, Godbold uses building a snowman as a metaphor. “If you think about someone building a snowball for a snowman, you have to start a small snowball rolling at the top of the hill to get it to be a huge snowball at the bottom of the hill. In the beginning, that snowball isn’t very big. It’s very much the same in an LST camshaft, we need to crack the door, and get everything moving” he says.
In addition to making more power, there was a somewhat unexpected side effect of the new valve opening methodology. “When Comp developed the LST profiles, We didn’t start thinking about durability, we were thinking about performance. The idea was, if we could get off the valve seat a little more smoothly, get a little bit better performance out of the valvespring, and then we could do some more things to get more air involved,” explains Godbold.
“What we didn’t expect, was that it would increase durability. In some professional drag racing classes where they were only getting six to eight passes out of a valvespring, they started calling in saying they were getting 20 passes on the same springs.”
Previously, power and the durability of a valvetrain were like a see-saw. Many professional motorsports teams often chose the extra power of a short-lived valvetrain instead of giving up some ponies for an extended valvetrain lifespan. “If there’s one thing to take away from Low Shock Technology, is that the options aren’t power or durability, it’s power and durability,” says Godbold.
“By slowly loading the system before we open the valve, we don’t shock the valvespring, we get more area on the backside to better fill the cylinder, all while putting less stress on, and getting better durability from the system. The Low Shock Technology has been a multi-year drive to learn how to get the most power out of your current LS package. This isn’t just another camshaft. It’s a totally new way of designing a lobe profile.”