so i’ve been doing my research about catch cans and all these forums i’m reading just aren’t answering my questions.

it’s a b18c4 which will be running around 26psi when tuned. which catch can system/setup will be suitable for this type of application? i’m seeing people suggest keeping oem pcv system and having 2 lines from the front of the rocker cover to a catch can, but then i’m also reading people say delete pcv system and have 2 lines from the back of the block? then i’m seeing people say delete pcv and have 2 lines from the rocker, so the answers are all over the place but obviously everyone does it different and has different applications. i do however understand that running the lines from the valve cover is preferred as the 2 ports on the back of the block are oil galleries that move oil from the head back to the sump (iirc)?

my first initial thought was to delete pcv system and have 2 lines going from the rocker to the catch can and then another 2 lines from the catch can to the back of the block which i think would act as the drain but i know drainbacks are frowned upon, so im questioning this.

does anyone have any idea which setup would be best for high boost (being roughly 26psi)? i cant find a clear answer so some knowledge from people who have done this before would be much appreciated

 

I don't see how this is still a question. There's even a sticky with a step by step.

 

ironically i read that thread after posting this and am probably going to go with it. i’m new to this site and didn’t know those sticky’s existed.

only thing that has stumbled me is the purpose of the line going from the intake through a check valve to the valve cover? i’ve seen a bunch of people delete the oem pcv system, run 2 lines from the back of the block to a catch can and blocking the pcv nipple on the intake and putting a little filter on the valve cover.

since you seem to be so knowledgeable could you advise?

 

Youtube the theory for any combustion engine to develop a good understanding.

​​​​i wrote a great explanation years ago if you dig thru my posts.

 

Either will work fine. I don't like oil in my intake at all so I doubt I will go with check valve route (even though it is suppose to avoid that).

 

I run a 5/8” hose from my sealed catch can to my intake tube. I dont like smelling the fumes that come out of the catch can but that also helps pull a vacuum to the crank case (you want the least possible pressure in the crank case, boost adds pressure in there)

Ive also been draining my oil back to the block for over 10 years and never an issue. If you want to be one of those guys that thinks dumping condensation out of a can is “cool” go for it. Guess what, that same stuff is in the motor it just gets burned off when your oil gets to operating temp.

 

so the check valve will cause oil to end up in the intake? thinking about it from a simple perspective, if there’s no check valve when you’re boosting you’ll just be sending a bunch of boost into the top of the head right?

 

no my first plan was to originally do a drainback system so i could avoid emptying the can every so often, don’t really like the idea of it.

how does that tube hold up when making boost? is that where a check valve will be needed to prevent sending all your boost into the catch can?

 

The intake tube to the turbo. Theres no positive pressure there

 

oh right yes i see, misread what you said.

i’d do this but we dont have a tube on our turbo as theres no room at the min.

 

Have pictures of your setup Pepe?

 

 

Very interesting

So the valve cover vents to the catch can and it is sealed? Then the other side of the equation is the vacuum side of the compressor is also vented to the catch can and it never sees positive pressure?

Wouldn't this result in the turbo pulling in from the catch can the vapors/oil from the valve cover and you would end up with a oil covered compressor blade? I guess I'm not understanding what is going on here. The catch can never sees positive pressure, that much is clear.

 

If my compressor blade, intercooler, intake manifold etc was covered in oil do you think i would still have it set up that way?

 

Point taken but how does it avoid this?

 

The catch can should be like an air oil separator. A good catch can has baffles and a mesh to catch oil particles. You should be left with clean air exiting the catch can. A proper OEM works this same way. Think of the PCV as a metered air leak where as its applying the slight vacuum on the crankcase at all times, yet doesn't get gunked up.

 

Oil has to make its way all the way thru the hoses into the BOTTOM of the catch can up into the top hose and into the intake. At the same time its draining back to the block with the two hoses at the back of the block.

I want to add a pressure sensor to the block to see how well this actually works verses just a vented catch can.

 

If you have never drained a catch can maybe you don't understand the amount of dilution you get, especially on a turbo honda. I advise against a return. The oem does this to improve emissions. But the dilution in performance motors is a worse concern for us at least.

Dilution promotes foaming and foaming causes a cascading effect. Consider low detergent oils to help reduce froth.

 

Youre just mixing condensation with oil and staring at it in a can. Look up what temp water evaporates at and think about how hot your oil gets right under your pistons. I monitor oil pressure very closely and temperature.

 

The brown slurry is mostly petroleum and petroleum by products from what I've found. Thats what hangs around in your oil pan longer than the moisture, agreed.

 

Ah! I didn't know it drained back into the block. So 2 ports to the valve cover, 2 "return ports" to the block, and 1 port to a vacuum source before the turbo.

No smell of burnt oil and you get a vacuum source for your system and never a positive pressure situation. Isn't that the goal to begin with?

Might look into this as a "drain back" on my system.

 

Yep best of both worlds.

 

Hey no not 2 return ports on the block. Those are crank case vent hoses. The one or 2 you decide to run on the valve cover are venting crank case pressure from the head. The same oil galleys that allow oil to drain back down from the head also allow crank case pressure to travel into the head. Because of oil slosh on acceleration, the front of the valve cover is a popular choice. But the block has 2 vent ports (b series)

​​​The pic you posted is a great demonstration of the venturi effect

 

You know thats all connected inside the motor right?

 

Good Read. Thank you all for the polite discussion without getting all crazy about it.
I will have to address this stuff soon and it helps.