Another factor that can't be ignored, is that as changes are made that affect street manners, emissions may be impacted. Our understanding is that none of these cams have gone through the exemption process to be street legal, but all the companies are working toward that with various products or already have cams with EOs. The entire subject of emissions will have to be addressed by the entire market as we move forward into a new era of regulations. Banish further adds, "bigger cams alone don't destroy emissions, but when combined with good controls-good air-fuel ratio control-they can still meet emissions. The General Motors production cams that have evolved over the life of LS engines are proof of that, they continue to get larger and meet tighter emissions."
Cam Design Strategy
What impacts the driving manners of a camshaft? There are many factors and several, such as calibration, proper functioning of all the sensors in the engine, and other hardware, are outside the control of the cam, but do impact the cars ability to idle and drive in an acceptable manner. Even the closed loop controls algorithms embedded into the ECM can make an impact. Ask any calibrator and they'll tell you that some year Corvettes are easier to tame a big cam than others because of the controller.
The cam itself plays a big part though-let's talk through each factor that plays a role in the performance and driveability of the cam. Number one on the driveability front is the cam overlap. This is the degrees by which the intake and exhaust overlap (or don't). This factor is influenced by the duration and lobe separation angle (LSA). Those along with lift also impact performance of the cam. The profile itself, or the actual shape of the cam, affects accelerations, area under the curve of valve opening and the forces exerted on the valvetrain system (and therefore wear/durability). Lastly, the timing of the cam as it is installed changes the opening and closing events relative to TDC and usually affects the tuning of the cam-or where it makes peak power.
Each of these cams goes about its business in a different way, trying to meet different objectives. Some utilize tighter LSA centerlines and more overlap to obtain more performance. Some utilize lift to a greater extent. Higher lift with shorter duration tends to increase the accelerations and forces experienced by the whole valvetrain. In theory, you want a square waveform for your valve opening and closing events-instantaneous opening and closing of the valve. Since this isn't physically possible, designers choose an acceleration they believe they can live with for the application and open the valve as fast as possible to meet that number. Acceptable accelerations are limited by the rest of the valvetrain system-the weight, spring load, and natural frequencies of the system. The Mast Motorsports cam, for example, was originally "designed for a 6.0L L76 with solid stem valves. Higher accelerations can be used for the lighter weight LS3 valves, which still maintain control and produce better performance. This cam offers excellent valve control and durability for people who don't want to risk the health of their engine for the ultimate performance," says Horace Mast. Of course Mast has new cams for the LS3 since this testing was completed, and much larger offerings for those more concerned with greater peak power.
Arguably, the GM Performance Parts Hot Cam has probably been around longer than all the cams submitted, and by today's standard is relatively small, yet still made 17 lb-ft torque and 40 horsepower! This shows the performance potential even with "smaller" camshafts.