The short answer answer is to eliminate crank case pressure. If you have pressure in the crank case (engine block) building up to a point that could potentially slow down the rotating assembly (rods and pistons) wouldn't you want to alleviate that pressure? Yes!
Turbocharger setups benefit from these the most but there’s more than one purpose of having a properly vacated crank case system.
Ever notice your turbo has oil coming out from the inlet?
The reason for that is usually, if not always, crank case pressure building up and vacating to the path of least resistance, that being the oil return line that drains directly to the engines oil pan.
Excessive blow by from an engine with a loose piston to wall clearance will build up massive amounts of crank case pressure, thus vacating usually to the turbo first and valve cover PCV or outlet tube.
Factory original equipment manufacturers used a PCV valve which to return and re-use air that’s built up in the engine. The negative side effect of this is that there is oil in the vapors that get sent back through the intake manifold which then create carbon deposits on the top of the intake valves over time and thus reduce the engine’s potential for the highest achievable VE (volumetric efficiency).
An engine is essentially an air pump, and the more air/fuel we can pull in and fill up the cylinder with successfully and burn, the better.
If you want to increase the life of your engine and get the highest performance from your engine then it’s time to invest in an oil catch can! Click here to order our latest 4 port oil catch can.