Catch can flow discussion

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j91z28d1

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That's certainly true for the overwhelming majority of street operation, but at high-load or full-throttle operation when there's the combination of low/no vacuum and increased blowby, crankcase vapor will flow out of that intake side. Whether it's worth it to install a catch can on that side will depend on if you see evidence of anything other than a minor amount of oil in that tube or the intake tract after a stint of high-load or full-throttle operation.


there's a company that sells a 3 port can, the idea if plummed correctly, once the intake hits zero vacuum, the 3rd port is run to the intake duct pre throttle body, the air rushing by will create a vacuum to continue to pull crank case pressure thru the catch can and not just back out the clean side into the intake duct without the catch can.

there's also a clean air side, it replaces your oil cap with a mesh filled media to attract oil before the hose runs to the oem clean air spot in the duct.

but as you said, I don't believe my suv ever sees a non vac in the intake state, since it seems to be a tight engine blow by wise and it's not driven like a race car. I think I will be putting a 3 port on my ls3 car thou. Just been lazy.
 

BlaineBug

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That's certainly true for the overwhelming majority of street operation, but at high-load or full-throttle operation when there's the combination of low/no vacuum and increased blowby, crankcase vapor will flow out of that intake side. Whether it's worth it to install a catch can on that side will depend on if you see evidence of anything other than a minor amount of oil in that tube or the intake tract after a stint of high-load or full-throttle operation.
What PCV fittings would one even use on the passenger side??
 

BlaineBug

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Whatever would be the correct size for the hose.

The fittings that go to the large intake box/air tube are a larger diameter than the PCV fittings on the driver side of the intake manifold and the near throttle body as well. When I installed my catch can I did not see any way that it would be possible to add a second on the opposite, passenger side.
 

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