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[hr]A functional PCV system is even more critical to turbocharged engines. Turbocharged engines generate crankcase pressures far above those experienced by a stock motor. Add to this the less than ideal Saturn PCV system and you have a problem. Simply attaching a filter to the PCV valve will not cut it. The factory PCV system simply isn't up to the task, and unable to keep up, excessive crankcase pressure will result, causing poor piston sealing, blowby, intake charge contamination (which in turn introduces detonation), and ultimately ring damage. And because the Saturn PCV system relies on a vacuum source to operate, it will not function when the engine is under boost. This is because like the whole intake system on a turbocharged engine, it is pressurized when under boost. And since the PCV system is sourced by a vacuum source on the intake manifold....Well, you get the picture. But this is precisely when a PCV system is needed the most. One must find a means to evacuate excess crankcase pressure, which builds exponentially under boost and heavy load. This is where a air pump comes in. By using an airpump you introduce a vacuum to the crankcase. This will evacuate the crankcase gases at a much faster rate and help the piston rings to do their job. With very little crankcase pressure to fight, engine builders car run looser tolerances. With looser tolerances comes less friction and reduced parasitic drag. In addition, this may allow the use of single compression ring piston designs, which is another topic altogether. It is not uncommon for high compression and turbocharged engines to gain as much as 40 wheel horsepower with the addition of an airpump.[hr]