NVCS

NVCS is the acronym for Nissan Variable cam system, it is found in the RB25DE, RB25DET and the RB25DET NEO. NVCS is not to be confused with Hondas V-TECH system which alters lift and duration high in the rev range to give higher peak power. Nissans system uses cam phasing to increase low to mid end engine torque.

Optimal valve opening and closure position for a given duration is different for every RPM and load combination, NCVS gives the engine the ability to take these factors into consideration and alters the timing accordingly. This is done using an electronic solenoid which adjusts the rotation of the cam by a maximum of 20 degrees, the solenoid is controlled by the engines ECU.

The RB25DE and RB25DET found in the R33 Nissan skyline only use the NVCS system on the intake Cam. The R34 Nissan Skyline is equipped with the NEO version of this engine and both intake and exhaust cams use the NVCS system. The RB20DET and RB26DETT do not use NVCS.

Torque curve of a VG30DETT with NVCS off and on notice the low to mid torque increase with the system turned on.

NVCS makes a considerable difference to low and mid range torque so when it comes to upgrading cams or installing cam gears it is a good idea to keep this system in place. Some manufactures (like tomei's poncam range) make cams to work with NVCS I highly recommend you consider these. As the non NEO RB25's only have NVCS on intake side an exhaust cam gear can be used as a good cheap upgrade to improve mid to high end torque.