Pintobeantoes

My setup: 323GTX PCV on cold side, tee'd into crankcase vent hose, then routed into the IN port of the catch can. OUT port goes to molded FM silicone inlet hose pre-turbo. Copper scrubby in catch can. Filling up about 1/2cup of oil every 100 miles or so.. didnt have any oil consumption problems before routing the can in this way.

options I see fit
1. Add a restrictor to the OUT port, so there is less vacuum being applied to the catch can setup.
2. Put a small breather filter on the top port, which is currently sealed (VTA port)

I don't wanna drain this stuff back to the pan.. lots of combustion gasses in there.

Braineack

iTrader: (62)

Pintobeantoes

No both valve cover ports tee up before the can, only the intake side has a PCV, wasnt sure if I maybe needed a check valve on the other one too..

Braineack

iTrader: (62)

so like this?



or this without the port back to the IM?




seriously: I dunno what's with miata owners and not understanding catch-can routing and the sudden influx of people adding them at all.

Pintobeantoes

Yes as you stated second, routed like picture except IM is capped off. Installed because I had been running the PCV to IM, with CCV venting, and was getting a small bit of oil consumption and wanted to see if this could remedy the burning of the oil. It certainly has succeeded in that, but i think the turbo is pulling enough vacuum to just suck the oil being squirted into the head. Is there additional baffling i could install?

and thanks for the responses thus far, I have read a lot about routing but there isnt a reputable company sticking their neck out saying "this is THE way to route it"

Savington

iTrader: (31)

Routing the PCV-side hose to a catch can is a recipe for a bad time

Braineack

iTrader: (62)

absolutely open the vent on the catch-can. that breather line itself is already barely adequate, once you add all the plumbing and the can, it adds restriction. there's simply now not enough vent and youre actually exacerbating the issue. and if you don't gut the PCV that's also another restriction in the line -- so your crankcase is breathing less than before.

we have a ridiculously long thread on this topic.


but I'm pretty stubborn about staying 100% stock unless you actually have bad rings -- a run-of-the-mill street/autox turbo setup does not need a catchcan whatsoever if the motor is in good order.

matrussell122

iTrader: (1)

100% agree with the above. The only reason i added one was because i had a breather filter on the hot side that slowly got saturated with oil and dripped on the header. If you are dead set on doing one read the massive catch can thread and youll get a firm understanding on how they work and why they are used


edit: oh yea and i have ran a few thousand miles with nothing but maybe an ounce

Pintobeantoes

Matt my setup looks very similar to yours. Is your can routed to the turbo inlet? Only difference I see is you have a filter on the third and upper port (i have this one plugged).

sav, matt also has his pcv side routed up? And the related moroso FS add that keeps popping up shows ONLY the PCV side routed, with outlet going back to the IM. Can you elaborate?

i have read through many posts and pages of that thread, although admittedly not all of them.

Brain, I'll take pics to show the exact setup. From what I understand, if i am to go the catch can route, I'm best leaving my setup as is and just adding the breather vent to the can? And in your opinion, i should just let the PCV into the IM as stock and then connect the turbo inlet breather hose to the CCV port?

Braineack

iTrader: (62)

yes, you need to open the catch can vent up --- VTA is better than going back into the intake.


right now you're trying to drink a milkshake out of two coffee stirrers connected back through one coffee stirrer.

Savington

iTrader: (31)

...no? If you hook up the PCV-side to a can, you will get oil out of that side. Don't do that. It's not complicated so I'm not sure how to elaborate further.

matrussell122

iTrader: (1)

I drilled both the pcv port and vent port for a -10 sae fitting. it think it was a 3/8npt to -10 sae and a 1/2npt to -10 sae then both lines are running in to the VENTED catch can. i capped the port on the IM and have nothing going into my turbo inlet. I also re drilled the hole in the valve cover per the catch can thread and put copper scrubbers in the baffled areas also per the catch can thread.


By my understanding there are 2 ways to do a catch can.

1. The way i have it
2. have a sealed catch can running where between the pcv and IM and a second vented can between the Hot side vent and the Turbo.

Pintobeantoes

Lol ty sav, thatll do.

well since the filter on my ccv port never really got too saturated, i dont think i need the can on that side, it just puts out a small mist over time that kind of coats everything.. ccv filter goes back on.

ill just run the can sealed between the pcv and IM. Putting the filter on the can doesnt change the straw sizes, just effecitvely puts a slit in them making suction now impossible. I guess it depends on which side you look from, is positive crankcase pressure > the vacuum/suction provided by the turbo inlet hose?

i guess my original thinking was just to provide inlet vacuum to the crankcase to reduce pressure.. i guess its not worth the trouble?

MstrBlk

Just got off the phone with fm, and yea I think the way to go is either one can on each side, one can on either side, or no can at all. but never one can for BOTH sides. I'll post a pic of my current and incorrect setup and another in a short bit of the two can setup, although I'm sure it'll just be repeat information here

engineered2win

That's only correct if you still have a PCV. You need one vent for fresh air flow. Otherwise there is no issue with running both ports to one catch can if you VTA.

Savington

iTrader: (31)

I disagree

matrussell122

iTrader: (1)

save could you elaborate on this a bit more. I know it's a simple concept. But is the only reason getting excessive oil on hard left turns or I'm I just way in left field.

Savington

iTrader: (31)

There are three chambers inside the valve cover for baffling and oil separation. The PCV side is fed by one of those chambers, and it's highly unrestricted. This is designed to be sucked through a one-way valve (PCV) under decel and light loads only. Under WOT, the valve is designed to close and prevent all flow through this chamber/port.

The driver's side cover is fed through two restrictive, baffled chambers. It's designed to operate under a very small constant vacuum or no vaccum at all times, including at WOT. The baffling in the valve cover allows for WOT venting operation from this port.

If you vent the PCV-side port at WOT, you will get liquid oil no matter how healthy the motor is.

The correct method for running a catch can is one hose from the driver's side port only. The passenger side (PCV) port should be plugged or capped entirely.

I have found that VVT motors are prone to liquid blowby from the driver's side port for some reason. The internal baffling is a little different on the VVT valve covers than it is on the 94-97 or 99-00s. It's manageable at lower power levels with a catch can (<300whp) but at high power levels or under high cornering forces, you need something more substantial. Not sure exactly why this is, but I've seen it on several different cars and engines, and it's a VVT-specific issue. I've successfully dealt with it by using a Radium AOS plumbed back into the oil pan.

matrussell122

iTrader: (1)

So right no on my VVT motor i have a -10 fitting welded about 2" back from the oil fill and one where the pcv was. If i cap the pcv and run the hose from the top of the cover to the can then back into the pan i should be good. Where should i send the oil back into the pan since im welding oil pan drain fittings right now on the bench.

germanmiata

I think the problem is the hole from the middle baffle to the pcv side. If the oil condensate in the pcv baffle it cant run backwards because the aslope hole and the rtv seal to the bottom. The only way out is through the pcv port. My idea is to run rtv not all the way but steel wool in the baffles. I will post some pics tomorrow in my build thread