Nissan's Variable Valve Event / Lift (VVEL) System currently used on the 370Z & G37, but will migrate to other models combined with in-cylinder injection, turbocharger(s), & exhaust cam phasers (not used on VQ37 currently). Also an explaination of the VVEL linkage adjustment that is factory set and not to be touched (Nissan requires heads to be replaced if adjustment is changed!) for performance engine builders developing VQ37 engines. For more info on this subject try:
www.370.com
www.motoriq.com
www.jimwolftechnology.com
Update:
This rig was built a couple of years back as part of a project to build the 3.7 engine for a race engine program. Since then we have built special exhaust cams to match the high lift intake settings but never used them in racing. Due to the unique offset in the valve to cam centerlines that Nissan had to design into the heads to accommodate the VVEL system, the peak velocity of any exhaust cam profile will be limited by the offset wipe pattern radius, which is even more basterdized by the fact that the offset is on the opening side on one bank and closing side on the other, a real cam designers nightmare! Currently we use earlier HR heads that share the excellent coolant and gas flow paths, but with centered cam to valve alignment, allowing for conventional racing cam profiles on intake and exhaust. VVEL for race engines may have advantages, but there are some practical constraints that must be considered.