PCV and Catch Cans

[w0rt3x]

I understand that there might be some oil in the vapor from the positive crank case ventilation going back into the intake manifold, hence a lot of people install catch cans to separate the oil from the air.

One thing is not clear for me here - Why does the PCV need to be connected to the intake manifold at all?

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[DANA44]

Emissions back in the day it was just vented to atmosphere

 

[w0rt3x]

And now emissions AND OIL back in the engine, that's great

 

[UPRSteve]

I understand that there might be some oil in the vapor from the positive crank case ventilation going back into the intake manifold, hence a lot of people install catch cans to separate the oil from the air.

One thing is not clear for me here - Why does the PCV need to be connected to the intake manifold at all?

Vacuum. And without it, you completely lose the benefit and efficiency created by the PCV system. Negative airflow (vacuum) thereby pulling the air from the crankcase is the secret to new cars having better and better throttle response and overall performance and MPG. The PCV is the evolution of high-performance engine being fine-tuned from the factory.

(PCV systems are the same as lower pressure vacuum pump and we know they benefit engines without any question) The PCV system is a twofold deal because it's not only creates a negative vacuum in the crankcase it also pulls fresh air from the atmosphere into your engine. Which, is constantly introducing room temperature air instead of all the hot, stagnant air that happens when you run breathers.

 

[w0rt3x]

Awesome answer, appreciate it! Now it all adds up

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