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Old 11-19-2020, 01:34 AM   #602
Kingtal0n
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Quote:
Originally Posted by TheRealSy90 View Post
I know the factory S13 hoses off the vc T fitting have a restrictor "Pill" inside of them.
Do the S15 hoses have any restrictor? The rear vc to crank hose and the front vc to turbo intake hose.

All engines requires some restriction to fresh air inlet or the pcv will never reduce the pressure inside a crankcase.

In chemistry there is a condition known as dynamic equilibrium, which is where the pressure differential inside a container is made up for by the evaporation of liquid molecules to a gas phase. For example if a cylinder is de-compressed by a piston (larger volume from small volume) there will be a pressure drop, but if the cylinder contains liquid phase solution, some of that liquid can evaporate to restore the pressure. This is called dynamic equilibrium. There is a great picture of this example in a typical chemistry book.

The goal of PCV is to take advantage of the partial pressures of liquid phase molecules, as in the dynamic equilibrium condition, within a set pressure drop (difference) as a steady state, thereby pulling the lighter liquid phase molecules (oil is heavy and stays as a liquid, while partially burnt gasoline and unburnt gasoline is light compared to oil so it can become a gas or stay as a gas) into the crankcase gas/air, so it can be removed easily by the PCV system, constantly. thus maintaining the oil quality. To put this another way, the flow rate of the pcv system by itself is not enough to pull contaminants from engine oil and remove them; there MUST be some pressure drop in the crankcase to pull light molecules from engine oil, taking them from liquid to gas state. Simply hooking a pcv valve to the intake manifold and connecting the other end of the crankcase to the air filter tract is NOT enough unless the orifice has been adjusted to accommodate the flow rate and volume of the crankcase pcv system to give the necessary drop in pressure.

The pressure drop also assists the piston ring seal, thereby reducing blow-by, and improving compression (tightness) of the sealing rings. That is why PCV is ultimately the most important system on an engine to be functioning properly; and why I go through great lengths to stress the importance of measuring it when you modify the intake filter or duct work. Without a pressure drop, the piston rings performance will suffer, the oil quality will suffer, the engine will deteriorate more or less rapidly depending how poorly the pcv is setup. All the engine's oil seals will suffer when PCV is poorly setup, but oil leaks can be pressure washed and oil seals can be replaced, so that is a secondary concern to the engine internals cleanliness and engine longevity.

Note that in many engines, the "restrictor" is simply an orifice diameter. For example in Chevrolet LS engines the "restriction" is provided by the size of the hose on the valve cover (approx 10mm~) from what I can see visually. Since the hose on the sr20 is huge (20mm~ or more diameter) it needs that restrictor to reduce the orifice diameter to create the pressure drop.
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Last edited by Kingtal0n; 11-19-2020 at 02:12 AM..
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