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PCV catch can question

yeti

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Oct 13, 2010
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800
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san diego california
After converting to speed density If I understand this correctly, I should only get a straight barb fitting for the PCV if my crankcase pressure is high.

I’m spitting oil out of the oil cap under high boost.

I should be able to run a hose from the PCV to a catch can along with breather hose , run a outlet to my intake pipe ( it’s a Fp aluminum one so I’d have to tap it )

Someone correct me if I’m wrong please.

I’d order just a straight barb fitting for the PCV but can’t seem to find one online and don’t wanna take it out and head to hardware store😅


 

CutlassJim

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Jul 17, 2006
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Manchester, NH
I would just run one catch can. And if you get a check valve ditch the PCV valve as it works better anyway. When I had both installed the PCV valve would make a terrible rattle with the cams and low vacuum I have.

You could run the catch can with a filter on speed density and no line to the intake pipe. The whole point of it is that there is now less restriction in front of the turbo so there will be little if any vacuum in the intake tube. Let the pressure just vent out how it wants. Have a check valve on the filter so you can still pull vacuum on it while cruising and be nice to the environment.

I'm still on a MAF but I run mine like this.




EDIT: I put this in another thread too but these are the valves I run instead of an OEM PCV valve.

click

Also mentioned in the other thread is the fitting for the PCV hose on the intake manifold also threads into the valve cover to eliminate the PCV valve.
 
Last edited:

yeti

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Joined
Oct 13, 2010
Messages
800
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san diego california
Ok sweet thanks I just ordered the part from JNz

Awesome that helps a bunch I thought that would be the best idea but was not sure.

So plan is to route breather and line from PCV placement to catch can inlets and run outlet to check valve going to IM

If I butchered that understanding please let me know 🍻
 

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
Also are these not a good idea to use as a check valve because oil is being put threw them to some degree.

These are the ones linked in the dsm tech article on pvx systems
 

CutlassJim

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Manchester, NH
I just don't know the specs on them

A lot of the ones I saw that were that style were only rated to 15 psi, I run 26. Another concern for me was the opening pressure(vacuum) and rated temperature. A valve could be rated for oil but is it rated for hot oil vapor while sitting in a hot engine bay? The ones I picked were rated lower than I wanted but they've held up well for over a year now and I made sure to mount them closer to the catch can to keep temps down. Plus the ones linked are also rated for fuels which there is a lot of in blowby.

Even though the bodies are large I went with the 1/2" versions for the 4x flow over the 1/4" versions that you would assume is what you want since the fittings are 1/4" BSPT

Quoting yeti:
Ok sweet thanks I just ordered the part from JNz

Awesome that helps a bunch I thought that would be the best idea but was not sure.

So plan is to route breather and line from PCV placement to catch can inlets and run outlet to check valve going to IM

If I butchered that understanding please let me know 🍻



You will need another outlet (4 total ports on the can) for when under boost or the thing will smoke like a coal train on decel after a pull.

So another valve pointed in the opposite direction either vented to atmo or to your intake pipe.

I don't have a photo but I used an inexpensive Amazon can that has an "inlet" and an "outlet" one the side and then a port on top with a plug that you can take out to run a filter. I put a "Tee" fitting on that top port with the valves connected to it and then off to their respective places. Only one of the branches of the tee will be flowing at any given time so I wasn't worried about choking it. I used both the inlet and outlet as inlets with some coarse steel wool added to the catch can.

I just remembered that they do make fittings that can pull a vacuum based off flow across them, they extend in the tube a little and have a slash cut in them, that people liked to use in speed density setups. Muscle car guys sometimes use an exhaust version of it to just burn everything up and out the tailpipe.

Found it. Should work the same in an intake pipe:

1189_WEBL.jpg
 
Last edited:

yeti

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Joined
Oct 13, 2010
Messages
800
Location
san diego california
Got it, I’ll be using the valves you have linked thanks a bunch.

So if I got this correct this time.

My second outlet is going to be running to atmosphere with a filter on the end probably to be honest I probably won’t tap my intake pipe.

By having the valve in the opposite direction do you mean that the outlet is physically going in another direction as the one to the IM or are you saying the check valve needs to be running in the other direction flow wise.

Sorry for any Misunderstandings once again and thanks a ton for explaining this to me 🍻
 
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