COMP Cams' New 4-Pattern Cam Profiles - The Four-Lobe Symphony

Jake Amatisto May 30, 2013 0 Comment(s)
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In today's world of touch-screens and digital technology, it's no surprise companies are constantly finding new ways to get the most performance from their products. It used to be a challenge to make 500 hp on pump fuel, now it's hard not to make that much, even with conventional parts. This incredible performance can be attributed to relentless innovations from our trusted aftermarket brands, and one company you can count on every year for innovative performance products is COMP Cams.

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At last year's SEMA show we were intrigued by COMP's new 4-Pattern camshaft profiles, which is a line of hydraulic roller cams designed to optimize valve events based on runner length. "The idea is to balance cylinder-to-cylinder performance in any V-8 application with a center-mounted carburetor or throttle body," COMP Cams' Dan Hodgdon says. These cams, which are new to the general public but have been used in motorsports for years, are designed to more accurately control your engine's valve events, optimizing the valve timing according to the engine's runner dimensions. With single- and dual-pattern cams, the cam lobes tend to shut the valve too soon or too late, which gives up precious gulps of air that your engine could otherwise use to make power. These cams however have four different lobes; one intake and exhaust design for outboard runners and another intake and exhaust lobe for the inboard. Using high-end equipment, such as an ADCOLE camshaft inspection system that is accurate to better than seven decimal places in lift measurement, COMP is able to design and check these cams on three "cuts" or areas on all 16 lobes to show the exact duration and angular changes that are made on the 4-Pattern cams. You actually get a read-out from this space-age machine when you purchase one of these bumpsticks. The engineers at COMP have essentially fine-tuned cam lobes to open and close at the perfect time in the V-8 engine cycle and the result: a better performing single-inducted powerplant.

"If you walk in the pits at a drag race you will see a weather station on almost every trailer, and if there's a significant change in conditions you'll see guys changing carburetor jets like mad men," Hodgdon says. "Talented engine tuners can even measure individual cylinder EGT and O2 data or closely examine the spark plugs and then tweak the tune-up on specific cylinders. Unfortunately, none of those jetting changes can alter the fact that the longer runner outboard cylinders will work harder at low rpm (launch, off the throttle stop, and at the gear change) than the shorter runner inboard cylinders. If you were to richen up the corner cylinders to help tune for those three critical low-rpm events, then at high rpm (when the shorter runner cylinder will make more power by pulling more air) either the outboard would be so rich or the inboard would be dangerously lean. Basically, none of the standard tuning methods allow the engine builder or tuner to treat the different cylinders differently depending on the rpm," Hodgdon says. After years of extensive research on NASCAR and F1 engines, COMP has found by making the cylinders run closer in air/fuel ratio mechanically (the cam) it can improve these tuning changes, making your engine run more efficiently while making drag runs more consistent. Although these cams aren't going to give you a tremendous power increase, the way they balance the engine's cylinder-to-cylinder ratios expands the rpm range, improves valvetrain stability, and since your engine runs more consistently, COMP expects these to be a valuable benefit for the bracket or heads-up drag racer. "I have great expectations for 4-Pattern cams in drag racing, but only in applications with a single, center location, throttle body, or carburetor," COMP's Billy Godbold says. "I believe it will be very important in bracket classes, such as the NHRA's ET, Super Stock, and Stock Classes, as well as NMCA and PSCA Index classes. However, once you go to multiple throttle bodies and common runner lengths, then the need for individual cylinder valve timing optimization vanishes." On such setups, the intake paths (ports) are the same length, so the reflected wave (which the four different lobes are designed to "catch" by optimizing when the valve closes) would return at the same time from opening, so the improvement would be nil.

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These profiles came to fruition when the engineers at COMP set out to improve on the Xtreme Energy line, and they were willing to use some unconventional methods. "As we started trying to make a cam series that was significantly better in performance than the Xtreme Energy, it became clear that if we want about 8-10 better across the board then we were going to have to find 2-3 hp in about three to four places," Godbold says. "In other words, the only way to make +10 was to find a couple of +2s and a couple of +3s. The 4-Pattern was part of the "kitchen sink" approach to making a better Xtreme Energy cam, but also makes for a great addition for anyone picking up all the little nuggets to make their gold (power) haul as big as possible."

This isn't the first time we've seen what average enthusiasts would consider out-of-the-box thinking either, as we remember when the 4-7 Swap Cams came out we were also intrigued. By swapping the lobes (firing order) on the number 4 and 7 cylinders in big-block Chevys (and other engines), builders found that the engines ran smoother and got some horsepower gains, but this is something else entirely. Godbold explains, "The 4-7 swap deals more with the cylinder head heating and crankshaft torsional effects than the air/fuel ratio balancing that we are addressing with the four-pattern cams, but we could address those together and we probably will on some of the later mechanical roller race cams in the 4-Pattern family, especially on the Big Chevy bracket race side where 4-7 swaps are quite popular;" he says.

Expect to see COMP's 4-Pattern cams in a street hydraulic roller line for small- and big-blocks, but they will grind custom 4-Pattern cams for any application, and according to Godbold, you will see part-numbered race cams rather soon.

1304 Chpp 06 O COMP 4 Pattern Cam Profiles Air And Fuel Ratios Of Runners 7/13
1304 Chpp 07 O COMP 4 Pattern Cam Profiles Cylinder Ratios 8/13

The data on top shows the air/fuel ratios of both inboard and outboard runners, and next to it are the ratios of each cylinder with the 4-Pattern cam installed. As you can see, the second one shows each cylinder being more linear throughout the rpm range.

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Some real dyno data from COMP shows a better average with a 4-Pattern cam than one with a single pattern. This comes from a more accurately controlled lobe shape that closes the valve at an ideal, precise point in the engine cycle in order to “gulp” the most air and fuel possible.

Secrets Revealed

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According to COMP, the 4-Pattern cams are broadly used in professional race engines, such as those in NASCAR to Formula 1, but for a while were not viable for the average person. In general, the methods to achieve a well-tuned symphony from cylinders that don't always "want" to behave the same gets rather complex, but in the case of long outboard and short inboard runners (like small- and big-block V-8s), the solution has been well-addressed by small tweaks in valve timing by professional race engine builders for many years. Hodgdon says, there have been three obstacles that kept this mostly in the NASCAR-only world for years:

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1. Every NASCAR race team believed they were the first and only COMP customer using this approach.

2. Grinding a cam with four masters on a manual grinder is tremendously time consuming and expensive.

3. Properly inspecting a camshaft ground with multiple designs on multiple centerlines in not easy.

Fortunately for us regular folks, the NASCAR proprietary issue disappeared somewhat with the new EFI manifolds that are far closer to equal-length runner designs than those used throughout the last two decades. At the same time, COMP Cams has brought in six new Okuma CNC grinders that are much better suited to grinding complex camshafts and with two state-of-the-art ADCOLE inspection gauges, the inspection hurdles have been at least mitigated.

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In order to design complex cam profiles effectively, a ton of measuring and dyno testing must be implemented. Many of COMP’s dyno mule engines are equipped with wide-band 02 sensors in each exhaust tube so they can monitor the air/fuel ratio in individual cylinders.

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