I'm running a Comptech SC w/AC. Stock boost. After playing around with the Godzilla and Greddy BOV's, I've noticed a little "blow-by" coming from the BOV.

If this blow by is a mix of oil and steam and it's vented to the atmosphere then I should not be worried about oil in my intake.

Do I only need a catch can if I am venting back through the intake elbow?

The reason I ask is because I'm assuming that if I ever go back to the stock bypass valve which vents to the intake elbow.....then I would be getting oil in the intake correct?

Can someone explain in laymens terms the purpose of the catch can....and if it's even needed with the stock Comptech SC?

Thanks for educating me.

Tim

 

You can employ 2 kinds of catch cans - one that vents to atmosphere (with filter) and one that is "inline" and vents back into the intake manifold. Either one will eliminate or reduce the amount of oil vapour going back into the combustion chamber. Some will say that the PCV system needs manifold vacuum to draw the oil vapour through the valve or it won't work and thus you need the "inline" type.
I think that if there is enough pressure, it will come out and thus, I've been using the "open" one with filter and plugged the entry into the intake.
I've also "Td" a line from the front breather in the valve cover into the same catch can as depending on what phase the engine is in, oil vapours can come out there, too. Over a period of about 6 months, I get about 20 cc of oil and maybe 50 cc of water in my catch can. However, I don't track my car and it has been noted that it's track duty that pukes out the most oil into a catch can.
A catch can has a series of baffles that cause oil vapour to settle out and go back to a liquid state, staying in the catch can.

If I'm not mistaken, your Comptech's bypass allows pressurized air to be released back into the blower's intake when the throttle is slammed shut. That pressurized air originated from the outside atmosphere and should contain no oil anyway, unlike the stuff that comes out of the engine via the PCV and front breather.

 

So is it recommended to have one? How come I've seen N/A cars with a catch can?

Without moving this to "s2000 talk" because of product inquiry.... is there a recommended catch can for the FI setups?

I'm assuming that the install is fairly easy.

Correct me if I'm wrong.

Without asking too much....if you have pictures of the setup...it would help.

 

Product enquiries mostly get moved out of UTH. Forced Induction is not quite so strict.

The FAQs at the top of Technical has a couple links about this. Here they are:
https://www.s2ki.com/forums/index.php?showtopic=270320

This ones mine:
https://www.s2ki.com/forums/index.php?showtopic=166796

Whether or not these things are "recommended" or even needed is a topic of debate. Some discussions about this in those threads. I did it because I just like to tinker with stuff. But for my personal use, as I've indicated, for street driving, I haven't prevented all that much oil from getting back into the intake.

 

Thank you very much...

This is EXACTLY what I need to read up on.

 

would something as simple as this work:

PCV-----CatchCan In CatchCan Out----Intake Manifold

So basically just using a can with an inlet and outlet?

 

I believe this has been done and has also been shown to collect oil, but again, amounts vary.

 

Everytime I take my PCV valve out I notice oil on it but I never find any coming out of the BOV and my throttle body opening is clean. I'm curious to see if I would collect any oil out of the PCV. I think I'm gonna try it.

 

The entrance to the intake from the PCV is near the rear of the manifold. I don't think much oil (even if present) is going to make it "upstream" back to the throttle body area.

 

I drain about 3 tablespoons of oil from my catch tank every oil change, from street driving. I'll see a little more after a track day.

This is a functional oil seperator, with baffles inside the can. The Cusco, and many other catch cans are not baffled, just big shiny expensive cans.



The "JDM" way of mounting a catch can is to run both the PCV hose and front breather hose to the can, and vent the can to atmosphere. some oil will collect, but your not using the engine vacuum to "suck" crankcase vapor through the PCV.
Some more pics:




This is a homemade can, made from a A/C reciever drier, Total material cost, 12$