Positive crankcase ventilation systems and engine systems including the same

A positive crankcase ventilation (PCV) system in an engine, the engine includes a crankcase and an intake manifold, the positive crankcase ventilation system comprising:

• a PCV pipe coupled to the crankcase;
• a first PCV branch and a second PCV branch extended from the PCV pipe and to be connected to a first through-aperture and a second through-aperture, respectively, wherein the first and second through-aperture are positioned on an intake manifold body of the engine and spaced apart each other, and wherein the first and second PCV branches are configured to route a blow-by gas in the crankcase to the intake manifold;
• and
• a variable valve to regulate a blow-by gas flowing through one of the first and second PCV branches in response to an engine cylinder deactivation.