The valvetrain is, as usual for Honda, quite complex and clever. The new i-VTEC system combines Honda's traditional VTEC with continuously variable intake cam timing, or VTC. The two systems are essentially independent of each other. VTC advances or retards the intake cam over a 50-degree range, depending on operating conditions. Retarding the intake cam at idle virtually eliminates valve overlap for optimum idle stability. At cruise, the intake cam is advanced, and the high overlap condition results in the dilution of the intake charge with exhaust gases. This internal exhaust gas recirculation actually reduces NOx emissions and eliminates the need for an EGR valve. At wide-open throttle (WOT), the valve timing varies, depending on RPM. If you're ever played with adjustable cam sprockets, you've seen how some cam timing settings give you better power at low RPM and others benefit high RPM. VTC simply keeps the timing optimized at all times. In addition to the VTC, the familiar VTEC system is still at work in the Type S engine. Three cam lobes and three rocker arms are used. The outer rocker arms push directly on the valves and follow relatively mild cam lobes. The center rocker arm, which follows a far more aggressive cam lobe, just floats between the other two, pushing on nothing. At the changeover RPM, a pin is pushed through all three rocker arms, linking them together. Since the center lobe opens earlier and farther and closes later, the newly united rocker arms have to follow the big lobe. This is essentially the same system that was used on the B18, but the rocker arms now follow the cam lobes with big rollers to reduce friction. Roller rockers were used on the S2000 as well. The S2000 also used a rifle drilled VTEC engagement pin to reduce valvetrain mass slightly and although we couldn't see it on the K20 (RSX engine), a similar design is probably being used here.