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Purpose of the Clean Side Separators

Posted by on 12/9/2016 to News

Clean Side Separators

Here at McNally we offer two types of Clean Side Separators. Our regular CSS is made of heat resistant plastic and our Premium CSS is made of billet 6061 T6 aircraft grade aluminum.

The Clean Side Separators are specially designed for use with Catch Cans to trap and remove oil vapors from the clean side of the oil separating system while retaining 100% MAF metered air.

  • Improves Engine Performance
  • Engine Runs Cooler
  • Increases Fuel Efficiency

Clean Side Separator Function

The Clean-side separator solution addresses that small amount of oil vapor that enters the intake air charge upstream of the throttle body during wide open throttle operation when the intake manifold vacuum is not present.

The Clean-side solution allows 100% MAF metered air entry while trapping the oil during wide open throttle operation and allowing it to return back into the valve cover as soon as the throttle is lifted.

It simply installs as a direct replacement for your stock Oil Fill Cap allowing you to delete and replace the stock OEM hose. This is an add on replacement for your stock Oil Fill Cap. The kit comes with vacuum caps and fittings if needed to connect to your intake air inlet tube.

Our plastic and aluminum clean-side separator incorporates an internal coalescing material. The aluminum clean-side separator also allows you to unscrew the top for a quick inspection or cleaning.

Although approximately 90-95% of the oil ingestion via the intake air charge enters via the “Dirty” or “foul” side of the PCV system, the other 5-10% enter via back flow through the factory “clean” or “fresh” side tube. This occurs mainly when accelerating or at wide open throttle when intake manifold vacuum drops to zero and crankcase pressure is allowed to build. This pressure will seek the path of least resistance, which is backwards flowing into the intake air bridge assembly bringing in oil mist and other contaminants into the intake air charge. While this will not cause severe issue with a port injection daily driven engine, it will cause detonation and reduced power and fuel economy, and in a performance engine, especially forced induction.

With a direct injection engine, this contributes to the intake valve coking issues all direct injection engines experience.

Regular or Premium Clean Side Separator.

Both Regular and Premium Clean Side Separators function the same. Regular being the more affordable model is recommended for vehicles that are in a warmer climate and environment. The metal one is made of billet 6061 T6 aircraft grade aluminum and is recommend over the plastic one in cold weather markets that may break if used in sub-freezing temperatures. (the aluminum model can safely be used in all temperatures). Both models contain stainless steel coalescing media in the separation chamber to trap and retain the oil for the periods of low or no intake manifold vacuum VS the OEM unit being a simple empty chamber. This allows most of the oil to be trapped VS a smaller percentage, and also returns it to the valve cover as soon as vacuum returns during deceleration, idle, or cruise.

One last word about the Clean Side Separators. Engines with high horse power will produce an exceptional amount of air flow. There is a point when a Clean Side Separator can not handle such air pressure.

When you purchase a Clean Side Separator you must consider, Affordability, Climate and Environment (sub-zero climate need a premium CSS) as well as the overall horse power of your vehicle.

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