Using SCV Solenoid to Control Vacuum for PCV Valve.

From my240

It is widely debate what to do with the PCV valve on turbocharged applications of the KA as from the factory the KA is naturally aspirated. The PCV valve and related system is not meant to and can not handle pressure above atmospheric pressure, or rather pressure created by a turbocharger.

First we need to explore what the PCV does and why it is important. PCV stands for positive crank ventilation. What this means is it uses the vacuum of the engine to draw out <<toxic>> gas from the crank case from the lower timing chain area. This gas is detrimental to the oil and ages it quicker if not drawn out of the crank case. Because it is the vacuum of the engine withdrawing this gas, the gas is burnt with the air pulled from the intake. In my opinion my it should be named NCV or neutral crank ventilation.

Quick sidebar, what is vacuum you ask? Vacuum is negative pressure created by the

On the KA the PCV valve works most efficiently at idle when the vacuum is the highest.

On my KA intake manifold and on the 95+ KA the SCV were removed. SCV, stands for swirl control valves. These valves close at idle (which drastically reduce the orifice leading to the injectors and ultimately the piston for combustion. This reduced orifice drastically charges the incoming air with more velocity, swirling the incoming air. The swirl mixes the air more evenly and burns more of the fuel at lower RPMs. It is debated why Nissan removed these valves but ultimately Nissan did and they yielded the same horsepower and torque specs as the previous configuration.

I own a 93 240SX with the original engine and wiring harness, so I have the plug for the SCV solenoid. Obviously the 95+ KA won't and I believe this might not work on the SOHC KA either.