Originally Posted by TX Tahoe Z71

The schematic posted up is for turbo/centrifugal s/c's. Like I said above, check valves aren't important on roots/lysholm blowers since they won't be boosting the crank case. With the exception of the line running to the turbo, which isn't applicable for blowers, that is how you should hook up a catch can. And the addition of the check valve on the breather is to keep the oil smell out of the cabin. I don't want to smell oil all of the time when driving around, nor do I want oil spray in my engine compartment. While the check valve prevents pressure from being released through the breather, the crank case pressure is vented back into the intake, through the catch can.

Originally Posted by 1989k1500

All of my friends with boosted vehicles have them vented to atmosphere and none of them smell like oil, nor do they cover the engine bay in oil. They will let some out right near where its vented but its not much and you can never smell it.