Advantage By Design - The COMP® Formula For Success
You can purchase cams from separate manufacturers with identical duration and lift numbers, but more often than not the camshaft from COMP® will outperform its twin. That’s not luck. It’s due to the “systems” approach to engineering and manufacturing that COMP® engineers pride themselves on.
When choosing a cam, the stats in the catalogs can tell you a lot, but they won’t tell you everything. A great camshaft is more than simply duration, lobe separation, overlap and lift. Getting those factors right will make an engine run, but meticulous attention to every movement in the valve train is required to make that engine run as efficiently as possible. As a result, two cams that have similar or identical lift, duration and lobe separation numbers can produce vastly different results if installed in the same engine.
Billy Godbold is the lead cam designer for COMP®.
Billy Godbold, lead cam designer for COMP Cams®, offers the perfect example, “As a general rule, the smaller the seat timing, in terms of degrees of duration, ground into a camshaft, the more responsive the throttle response will be. But the more duration you put into it at 0.200 lift, the more airflow you are going to get.
“But what you can’t tell from that is how stable the cam is,” he continues. “There’s a line there somewhere, so if you keep the seat timing the same and increase the duration at 0.200, somewhere you are going to reach a point where it just doesn’t work anymore. On the surface it may not make sense because you are still capable of flowing more into the combustion chambers, but what’s happening is the lobe has gotten so aggressive that it has started bouncing the valve just a little bit. That causes you to lose cylinder pressure and the net result is lost power. So you have to be able to look at the valve train as a whole to be able to say, ‘I think we need to pull back on that 0.200 number and we’ll make more power.’”
What Godbold leaves unsaid is that being able to make that call requires an intense understanding of everything that’s going on in an engine. And that speaks to one of the great advantages COMP® holds when it comes to producing camshafts that not only win races, but championships. The company’s expertise isn’t just grinding camshafts – after all, anyone with the right equipment can do that – it’s also understanding what is going on with the valve train as a complete system and developing the best ways to improve it. Race wins are hard enough, but championships are extremely difficult because you have to have an engine that not only makes great power, but it has to be able to do it week after week without breaking. Making big power while still keeping the valve train under control isn’t impossible, it just seems like it to most manufacturers.
The modern systems approach to engineering requires hours of Spintron testing, during which engineers monitor every single movement in the valve train.
“Our mentality is that we aren’t working with individual components,” Godbold adds. “We’re working with complete systems. And that’s a tremendous advantage because if you are just concentrating on one component, like the camshaft, then it is hard to know everything that is available to you. For example, as we develop better rocker arms, we are able to decrease the weight of the system and increase overall stiffness in the valve train. And when you reduce flexibility in the system, you can get more aggressive as a cam designer.”
With performance engines using aggressive cams, strong valve springs and lightweight components, flex in the valve train is obviously an issue. The easy answer is to simply change the cam specs in an attempt to compensate for that flex, but Godbold says the problem with that is flexibility in the valve train components causes the camshaft’s effective specs to change through the RPM range – and it’s in the opposite direction that you want.
Stress on the valve train increases with the RPM level. So at low RPM levels, flex in the valve train is low and the camshaft’s lobe design is accurately reflected at the valve. And when it comes to engine performance, what’s actually happening at the valve is the only thing that matters. As the RPM increase, any flexibility in the system will show up with the pushrods bending or the rocker arms twisting. The result of this is it causes the valves to open later than the cam tells it to, making the camshaft’s effective duration appear smaller at the valves. This is exactly the opposite of what you want. Ideally, the camshaft is smaller in the lower RPM ranges to improve throttle response, and the duration grows at high RPM levels to help the engine pull in all the air and fuel it needs to make big power. So adjusting the cam’s specs to account for valve train flexibility is only a band-aid at best. It actually hurts engine power and throttle response in many cases.
Making sure that the hundredth grind is as perfect as the first grind requires precision equipment such as this Okuma CNC-grinding machine.
That’s why Godbold says the philosophy at COMP® is to design the absolute best cam for each specific application, and then match everything else in the valve train to it so that the valves follow the cam’s “directions” as accurately as possible. As a result, where many valve train systems show a reduction in effective duration as high as 30 percent at redline, many COMP®-designed systems can cut that amount down to eight percent. And though continued R&D, that number is still shrinking. The band-aid of designing a cam around other deficiencies in the valve train only creates more problems than it solves.
“Every little piece of the puzzle can make a huge difference,” Godbold says. “And believe me, we look at every little piece. We have to because we work with so many race teams in so many different types of racing. We also do consulting work with companies that do everything from the tiniest four cylinder engines like you might find on the back of a weed trimmer, to huge two-stroke diesel ship engines. So we are constantly taking what we learn from one project and trying to see where we can apply it in other areas. You would be surprised the things we’ve learned from Pro Stock and Top Fuel drag racing that we’ve been able to apply to circle track and street engines.”
Because they know how to optimize the valve train for the specific application, the engineering staff at COMP® can do things with the cams that would otherwise be impossible. They not only track the exact the optimum path of the valve from the moment it first lifts off the seat until it finally settles back on it, but they also take into account how factors such as the harmonics created by the movement of the valve spring can affect the movement of the valve. Once they understand these effects, they adjust the cam lobe appropriately.
A dedicated Quality Assurance Lab is staffed with trained engineers who use state-of-the-art measuring equipment to ensure only the highest quality products are shipped out to customers.
“Of course, you can’t ignore the other side of the equation,” Godbold adds. “It doesn’t matter how good your designs are if you can’t manufacture the cams to match the design. And not just one cam, but cam number 100 and cam number 1,000 have to be just as good. The guy who buys cam number 1,000 doesn’t care how good the first 999 were, he only wants to know that his is the best it can be.
“We’ve invested an incredible amount of money into our equipment and our people so we can produce camshafts that are every bit as good as what we draw up on the computer. That includes multiple Okuma and Adcole machines to CNC-grind the cams and then check them for quality assurance purposes. The Adcoles are a really big investment, but they allow us to check the quality of the cams we produce, and they’ve helped us learn what we need to do to tighten up our tolerances.