ok, i have one catch can i want to know if i take out the pcv valve and plug its original location as well as plug the intake vent hose
run one line from the crank vent to the can and the return line goes back to the manifold with the pcv inline

similar to this thread


heres a diagram of what i wanna do.
NOTE: i know i spelt "pcv", "pvc", that was an accident lol


i dont wanna run two catch cans and dont wanna vent either to atmosphere.
right now im venting the crank to atmosphere have the intake plugged and a catch can in between the pcv and manifold.
any help is appreciated thankyou.

 

Not a good idea, IMO. When the intake is pressurized and the PCV valve is closed, where does the crankcase pressure vent to when it's at it's highest? It doesn't have any where to go.

IMO it's more important to keep oil from coating the intake, turbo, IC and TB so I installed my catch can between the crank vent and the intake pipe.

 

well im basically copying this just running the gases from the catch can back to the manifold instead of dumping them into the exhaust stream and relocating the pcv valve back into the system just AFTER the can so it wont pressurize the can to boost pressure.

 

Id just vent the catch can to open air and plug the hole on the intake manifold. Also route the back PCV valve to the catchcan also, dont just plug it.

 

Well I'm going to relocate the valve into the return line from the can to the manifold and plug its boriginal location

 

bumpp i really wanna try this setup just wanna make sure relocating the valve is ok and aparently capping where the pcv valve was is ok to do.

 

Where does the crankcase blow-by pressure go when the intake manifold is pressurized by boost? Your proposed setup will pressurize the crankcase to whatever pressure is in the intake manifold.

 

Well the valve would hold pressure from the line through the catch can like it normally would and open when in boost so it wouls share pressure with the manifold and crank no? But blowby should follow the line from the crank vent where it would normaly go from the vent to the intake. Now goes from the vent to the can to the pcv valve to the manifold nothings getting deleted beside the two vents. I just want one. Blowby goes through both vent and many people do the exhaust scavenge so I don't see this being a problem plus I'm keeping the valve after the can so its not pressurized under boost and only what the crankcase is pressurized to.

 

The crankcase should never be pressurized at all and should always be vented to atmosphere at a minimum. Your proposed setup would be okay if you add a atmosphere vent to the catch can.

During vacuum conditions crankcase pressure vents through the PCV valve and into the intake manifold. Scavenging of blow-by gasses is supplemented by drawing fresh air in through the intake pipe. Whenever the PCV valve is closed, crankcase blow-by vents back into the intake pipe. Your proposed setup doesn't allow a second path for the blow-by gasses. This is why you need to either vent the "crank vent" or catch can to atmosphere to avoid pressurizing your crankcase.

 

ok i thought both would be forced to travel through the one line. so venting the crankcase to atmosphere and running a catch can between the pcv and manifold is "good enough" my intake after supercharging use to be saturated in oil so i opted to vent it to atmosphere since it was cheap. and i looked at the pcv to find some oil on that as well so i threw in the can. should i reverse the two? vent the pcv to atmosphere plugging the manifold vacuum line and run a can in between the crank vent and intake? thanks!

 

IMO your current setup is pretty good. It allows the system to operate as designed. The only problem is the potential for oil vapors to vent through the "crank vent" filter and coat the engine bay. If you're not having a problem with this, I'd leave what you have alone. By completely bypassing the intake pipe connection you've eliminated the possibility of blow-by oil coating the turbo, IC and TB. Your catch can reduces the amount of oil entering the intake manifold.

I wouldn't reverse your setup. The fresh air scavenging of the crankcase blow-by gasses by intake manifold vacuum is important to keep moisture out of your engine and oil. A filter on the crank vent allows fresh air to enter during low loads and blow-by gasses to vent during high loads. You're welcome.

 

Haha nice. Thanks again. Watch out emissions, here I come.

 

Good luck!

 

just do what I did ... only cost me like $2 plus comes filled with yummy energy filled liquid substance.