PCV Valve Bung for Nissan RB25 SpecificationThe PCV system (for Positive Crankcase Ventilation) is present on all factory RB25DE and RB25DET engines : it allows the oil vapors to recirculate in the intake manifold to be burned in the combustion chambers reducing emissions. However this system is a problem for tuned engines : the oil vapors leave a residue in the air circuit in particular the intercooler also increasing operating temperatures and the risk of getting engine knock.Keep your engine running smoothly by blocking the PCV system with this forged aluminium bung and OEM Nissan grommet (part no. 11812-41B00).