Valvetrain technology is always evolving each year, and with 2010 already moving at full speed, you can bet that new ideas and developments are going to change the way we think about camshafts, lifters... anything that has to do with rocketing that valve up and down.



Our friends over at COMP Cams seem to be leading that charge, and they recently wrote a pretty cool article about what they think is the top 5 trends in race valve train development. Since these guys get to play with the "top teams" in NHRA, NASCAR, Dirt track, and even the 10.5 and Heads-Up Street Legal stuff, it's a good read.







Here's the original article in all of it's glory:



Big Developments Are Coming To Race Engines. Here Are 5 Of Them…



Every year, new innovations help push engine performance higher – cars go faster, old records fall, and new records are set. Some of the innovations from COMP Cams® Research & Development are poised to play a role in this development. As the 2009 racing season comes to a close, five important changes in valve train technology are working their way through the development cycle. And engineers at COMP Cams® foresee each of these playing an important role in 2010.



1. Increased Lobe Lift & Lower Rocker Ratios for Roller Cams



In the roller camshaft racing world, there are several factors that continue to push development in this direction. Ten or fifteen years ago, most professional race engines ran rocker ratios in the 1.5:1 to 1.7:1 range. Over the years, this increased to the point that most applications were running ratios close to 2.0:1. This was absolutely necessary in the top level NASCAR competition, where flat tappet lifters are mandatory. Other series followed suit, and that ratio increase certainly helped with both flat tappet and roller engine configurations of the day.



However, we now see most roller applications migrating back towards that 1.7:1 rocker ratio range, while engine builders are maintaining or even increasing valve lift. In order to accomplish this trend, there are more and more camshaft series being made available with higher lobe lifts.



On the circle track side, several new COMP Cams® high lift cam series are taking the place of the common lower lift series, especially as engine builders run lower ratios. On the drag race side, it’s quite common to see bracket racers running .515" lobe lift drag profiles, while the heads up and NHRA racers are running lobes in the .540" to .560" lift range. A few years ago, such high lobe lifts would have been considered exclusively Pro Stock.



2. Larger Camshaft Journals



The main initiator of higher lobe lifts and putting more motion into the lifter is the recent arrival of engine blocks designed for larger cam journals. Modern race blocks are now available with the camshaft moved higher with more room for larger journals.





With the advent of new-model engine blocks with raised camshaft centerlines, like the RHS® LS Race Block shown here, there has been a movement toward larger cam journals.



With the original Small Block Chevy engine, the camshaft journal size was 1.868". Because the lobe must fit inside that journal with some clearance, .484" lobe lift was the most you could grind a cam to maintain even a tiny .450" radius/.900" diameter base circle. This resulted in a cam core with only .850" barrel diameter between lobes. And the increased bend and twist limited how quickly you could move the valves without suffering valve train issues.



But with the newer generation of engine blocks accepting 2.165" (55mm), 2.362" (60mm), 2.559" (65mm) and 2.756" (70mm) journals, you can now achieve almost any lobe lift you want without compromising the stiffness of the core. Typically, you would like at least a 1.200" barrel and would prefer 1.300"+. Of course, it does little good to put a large journal on a camshaft if you then have to grind with a small base circle to clear the connecting rods.



For this reason, you see many of the newest blocks with the cams raised to allow for more clearance. For example, the new RHS® LS Race Block moves the cam up approximately two timing chain links to allow a full base circle size with a 60mm camshaft - even with a 4.600" crank stroke.



3. Custom Cores & Tool Steel Roller Cores



With more and more customized applications coming out, it becomes more unrealistic to have the correct core on the shelf for every application. Instead of the old path of “trying to make something work”, it’s now common to develop custom cores for given applications. With a custom core, the lobes are rough-milled and heat-treated to near final intent for much longer life. They are also clocked and positioned so that the lifters track down the center of each lobe, and the barrel size is maximized for optimal stiffness. With this, any provision needed for a given application can be made to suit the customer.





Custom tool steel core for a Ford Modular engine.



In addition to having the core layout customized for the application, we now offer several material upgrade possibilities. The most interesting of these options is Powder Metal Tool Steel for roller applications. This material has been the norm for several years for NASCAR flat tappet cores. But because of the increased strength, reduced wear, excellent toughness and through-hardened profiles, this is also taking hold in the roller cam world.



Through-hardening allows for much more final grind flexibility. If you design a core for .500" lift, but later want to grind that core to .600" lift, you can do that with tool steel with the only concern being that you may need to re-turn the barrel smaller. On any case-hardened cam, you would grind through the heat treat case.



4. Quicker Exhaust Lobes



The old rule of thumb on choosing an exhaust profile was to simply make sure you didn’t hurt performance. Many of the common exhaust lobes were either left over intake designs, or lazy profiles that seemed to take days to get the valve off and back on the seat. There were signs that the exhaust tended to prefer the soft seating velocities, but there was always a healthy debate as to the best choice.



Now, valve train experts at COMP Cams® are introducing new exhaust-specific designs that are by no means “soft” lobes but are still just a bit softer right at the seat than the newest intake designs. But COMP® no longer softens up the entire curve, so you see much more area on these new style designs. With these, exhaust pumping losses are lower and the toque curve is much flatter than with the slower designs. By optimizing around the seat, you don’t increase the risk of broken valves or premature exhaust seat wear, and the optimized overlap region helps the headers do their job of providing a low pressure signal back to the inlet charge.



5. “Hybrid” Hydraulic Rollers



Until now, you only had two categories of lobes you had to work with if building a race hydraulic roller combination. You could either run a hydraulic roller with a long ramp for noise reduction on the street that was optimized for use below 6500 rpm, or you could go with a tight lash solid roller that was designed for more rpm but around 0.016" lash.





NEW Short Travel Hydarulic Roller Lifters from COMP Cams®



But as engine speed and performance expectations with these engines have risen, it has become clear that neither of the paths formerly taken is correct. This led engineers at COMP Cams® to develop six new lobe families to bridge the gap.



Several of the new COMP® lobe series fall into a hybrid group of lobes that can either be run with COMP® Short Travel Hydraulic Roller or tight lash solid roller lifter applications. In an LS application using Short Travel Hydraulic Roller Lifters and the #26926 Valve Springs, COMP Cams® has several unique .675" valve lift lobes up to 7500 rpm without loss of control. Just a short while ago, this lift and rpm capability were seen as out of the question for a race hydraulic roller application.



So if you're a racer, engine builder of do-it-yourself enthusiast, take heed to this advice. These are the trends that will certainly assure that you're up-to-date, and if you capitalize on them, ahead of the competition.

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