Vented or Non-Vented Oil Catch Can?
 

I currently have a small 1 pint Jazz Catch Can with a K&N breather filter on top. Lately, its been filling up pretty quickly with watery fluids and am moving up to a larger 1 Quart size. The larger cans don't have breathers on them and I'm wondering if its even necessary.

Can someone please enlighten me on why a breather would be needed on an oil catch can?

Would one w/o a breather NEED to be routed back to the UIM?

Thanks.

This is for an FD running twins.

You'll want to release some of the crankcase pressure somehow. So you can either keep the line going to the UIM, or you can vent the catch tank (whether that's with a filter or plumbing it back to the primary intake elbow). I haven't installed mine, but I'll be running the outlet back to the primary intake elbow.

+1

I've got mine plumbed to the primary turbo so that it's constantly under suction. I'm pretty sure if you ru it just to the UIM, the boost with push back the wrong way.

My can is big enough, and the two inlets are positioned such that that no oil actually get's sucked into the turbo.

Hmmm...

I just have a tube coming from the filler neck to the catch can. It's basically the old Crispy style setup that has been on the car since the previous owner. The UIM nipple is capped off right now.



Another question:

Which larger sized catch can are you guys using?

I'm looking around and don't see many options that are easy to install in my cramped engine bay running the twins and all the accessories.

Thanks.

Yes. I was also meaning to retain the stock plastic valve to the oil filter neck.

I will be using the Greddy catch can (when I get around to installing it).

http://mahjik.homestead.com/files/FD...eddy_parts.jpg

Mahjik - if you have some time, can you measure diameter and height on that Greddy can? Trying to figure out where I could mount something like that....

Thanks in advance.

Sure, I'll post them late tonight. I will be mounting mine in the area where my airpump used to be, basically in line with the stock oil venting line which ran to the primary turbo elbow.

I had the Gotham racing catch can and I couldn't for the life of me figure out where I was going to fit it in my cramped engine bay either... So I sold it.

Then I replaced my '93 filler neck with the RE-Speed baffled one, blocked off the breather line to the UIM, and figured that'd be that. The very next time I took the car out to an autox, not even a track event, under hard right cornering at near redline, oil particles started spewing out my BOV whenever I got off boost just like before. So now I guess it's time to reconsider that catch can. That or I've got residual oil built up in my I/C and it's coming out.

Sorry for the rant. I know it wasn't helpful at all, but I had to get that off my chest.

I'm planning to mimic Crispy's setup:

1. Baffled oil pan
2. ReSpeed baffled oil filter neck
3. Catch tank

I'm hoping that should do the trick, but we'll see here in about a month or so.

I put together a catch can made from a bicycle water bottle and bike mount. It's got one line going to what was the center drinking spout to the oil cap, and another line coming off the cap that goes to the turbo inlet. It's WAY better than the GReddy I tried, because the GReddy requires that you dissassemble the whole bloody thing to empty it. I was filling it ever run.

I fill the water bottle ever run too (similar capacity), but all I do is lift it out of the mount, unscrew the bottle, dump, replace.

Sounds like a great idea.

Can you post a picture of that setup?

Basically 7" tall, the base is 4" x 3" (kind of an odd shape).

Thanks Mahjik.

That is pretty odd. I'm going to poke around and see where something like that would fit.


Now that Peter posted, I remember seeing a pic of his setup but I can't find it in a search anymore. I'll try again later.

^^^^

It may not be the latest, I've made like 6-7... one used a bicycle bottle with a little K&N lawn mower filter on top.... I'll try and snap one of the latest and greatest.

Whats the purpose of the baffled pan? Ill be running a REW with 2nd gen pan and it currently has no baffle

Johny

^^^

It's to prevent oil slosh on hard corners, that results in it being sucked up and out of the oil filler tube with the "crankcase" pressure.

Found your pic you were talking about.
https://www.rx7club.com/showpost.php...65&postcount=3

I bought a JM Fab vent catch can listed here

http://www.maperformance.com/store/p...at=1368&page=1

Does anybody have a diagram of where this should be routed? I'm not really sure how to hook this up. I will be running a single turbo.

How did this unit workout for you?.

I have a hand built aluminum box sitting above the oil filler with AN-12 hose into the filler. The vent tube goes into the side of the can and it has a small breather to atmosphere on the front. While oil still gets pushed up in hard right hand corners it quickly drains back down once I straighten out. I used to fill two quart oil cans in about ten minutes before I built the drain back box. Now, no issues. I have a screw in AN 16 fitting the top of the box for adding oil to the engine.

-Trent

Sounds cool. Post up some pics. I'd love to see this.

I'm getting one of these:

https://www.rx7club.com/attachment.p...7&d=1203618024

From this thread:

https://www.rx7club.com/showpost.php...&postcount=708

It fits in the area formerly occupied by a vacuum chamber.

afgmoto1978 is fitting a vmount setup in my car, and I'm getting the custom catch tank as well. Oil will be routed back to the crankcase.

It's a pretty cool piece of fab work.

Cool but most sanctioning bodies require something of larger capacity. NASA says 1 quart. I know the 1 pint is a bit small and can fill up every session on some tracks.

Since it doesn't require emptying, why should it matter?

What do you think a catch can is catching? :)

It fills with liquids and oils and the gases are either vented to atmosphere or recycled back into the intake tract. Eventually the oils and liquids that get trapped in there have to go somewhere... If you don't plan on emptying it, then you might as well just run the stock PCV valve.

Yes, I do know what goes in the catch can.

I spoke to Adam today (he built it) and it's designed to be emptied.

If you can't for some reason empty it when needed, the overflow goes back into the oil pan.

Since NASA doesn't exist in this part of the country (Northwest), and I don't road race my car, the smaller catch can is fine. Though I haven't checked the capacity of it, I believe it is more than the pint you suggested. I'll check it when I can.

The critical thing is that you vent BOTH sides of the motors. This way the motor is vented under both hard left and right turns. In stock configuration, with only a vent on the oil filler neck, sustained hard right turns will slosh the oil up into the filler neck and effectively block any exit for the motor vapors. The motor pressure will then quickly build and start forcing the oil further up the filler neck.

When I went single turbo I added a second breather line to my vented catch can from the now unused secondary turbo oil drain. Once I did this I went from filling a 1 pint catch can several times during a track weekend to maybe one ounce of catchcan fluid per weekend.

If you don't have a second turbo oil drain or still have twin turbos some people have tapped into the passenger side of the front motor cover for a second vent line.

Exactly right.
Baffling this and that will not fix the problem on a car that is tracked. Perhaps on a street driven only car that is not pushed it may help, but it will not really benefit, let alone cure the messy oil problem.

I also went from blowing a quart or more of oil after a 20 minute session to practically NO oil over the course of an entire weekend after venting the other side of the engine.

Pics and info of my setup starting at post #205:
https://www.rx7club.com/forum/showth...=oil+catch+can

Pics of my setup for people too lazy to click and read:

https://www.rx7club.com/forum/attach...2&d=1132727764

https://www.rx7club.com/forum/attach...6&d=1132728661

https://www.rx7club.com/forum/attach...7&d=1132728778

I haven't installed it yet, still working on installing the rebuilt motor and single turbo conversion.

I was thinking of just running a hose from one of the side ports on the oil filler neck to the vented catch can, and capping off the other side of the catch can.

gracer7-rx7 is this how yours is plumbed? Does it work for daily driving and drag racing?

Mine just has a hose from the top outlet of the RE Speed oil filler neck to the "catch can". The can has a K&N breather on it. My current setup is pretty ghetto. I'm using an empty quart oil bottle. My old Jazz catch can sprung a leak and I had to get creative as there isn't much space for this.


For DD, you don't need this. IMO, its a waste of time and space.

For track days, it helps to have it. Kinda depends on skill level and how frequently you do it. Go read the original thread (link below) on the topic to learn about it from people who know much more about it than I probably ever will. I'm certainly no expert on this topic.

For drag, no idea.

I started this thread to ask a dumb question as I was trying educate myself better on catch cans. I do suggest referring back to the original thread:
https://www.rx7club.com/forum/showth...=oil+catch+can
and reading it through as there is really good info on there from forum elders that will never make it to this thread.

Cheers.

You will need to vent the can to atmosphere or plumb the catch can before the turbo so it is under vacuum otherwise your oil pan will be under pressure from the vented gases. Otherwise, not only will you fill the can by blowing oil, particularly under acceleration with right hand turns, you will prevent oil from draining from the turbo. This in turn will result in smoke coming from the exhaust since oil is pushed passed the oil seals in the turbo.

Recently finished installing the engine mounted catch tank I made. It's resides in jkstill's FD. It's vented on both sides, the right side utilized the rear engine turbo oil drain pick up point. The capacity is slightly more than 24 oz. or 0.70 Liters. Will be playing with the design later this year to reach 1 liters. It's vented to atmosphere and like Jared said in the event it does get to the point of over flow the oil will have a chance to drain back into the oil pan. At the bottom there will be a remove mounted ball valve for easy drainage.

Later this year I plan on creating a GB for these units if anyone interested.

Adam

More Photos of the catch tank. See attached photos of the Driver side oil drainage setup.

Looks great but probably hard to make! If you do a GB I'll be interested.

Look out for that vent line you installed in the unused twin turbo drain. I had several rubber hoses, even covered with heat shielding like you did, melt on me under racing use from the exhaust heat. In the end I had to hardline it.

It's not hard to make, just a lot of pieces the weld together. I will be reducing the amount of pieces to weld by have formed tabs on all three vertical panels when I do the GB.

Good point John, better safe than sorry would the order of the day. A hard line up and over the bell housing wouldn't be hard to make. Just a pain to install if space is limited like Jared's setup.

Wouldn't the hard line just need to be long enough to get the rubber line a few inches away from the exhaust?

Yes, but radiant heat would eventually cause material fatigue. The hose wouldn't fail immediately, but over time the hose would become brittle and eventually crack. Something along the lines of a line that would go up to the top left bolt point on the LIM would be enough, but heat shielding would still be used.

Yes, that's what I run now and I don't have any problems. It doesn't have to be hard line all the way... just where it is near the turbo/downpipe

The first line I used had no heat shielding and died of the radiant heat pretty quickly. The second line has heat shielding over rubber and lasted a while longer but eventually melted itself off and caused quite the smoke screen on a hard left at the track.

The other lines I've had a lot of problems with are the lines to the external waste gate. It looks like you're running rubber lines on these too. I had to hard line the wastegate lines also. Rubber or Silicone hose kept failing even with a lot of heat shielding. Often the wastegate gets hot enough to melt the hose off the nipple.

You won't want to drain the contents of the catch can back into the oil pan and you shouldn't need to make the catch can larger by any means, especially now that you are venting the other side of the engine. If anything, make it smaller but in any case, nice work so far.

The drain back to the oil pan is only used when the catch can is nearly full.

Turbo drain line.

I'm using stock twins so that location wouldn't work for me. I'd love a quarter or liter sized catch can that fits somewhere underhood tucked away in a corner.

afgmoto: that catch can is a work of art, i'm gb ready. haha

An update on the catch can made by afgmoto1978:

I've done a few autox's now in late summer and fall, and just finished up a track day.

The catch can works very well. Perhaps larger vent tubes would allow more pressure to escape without losing as much oil, but I've put in 9 autox sessions and on the car, and only after 2 sessions today did can fill up enough show up in the sight line.

So, I'm happy with it :)

Look like a nice unit. I too am curious if this is getting produced for purchase?

I plan on doing another GB on the catch cans, just limited on free time while doing all my other projects. Keep an eye out late January for one though.

do you have a sec. turbo drain tube? i'd love to get one of those. thanks

Pm'd you silverTRD

To the turbo breather or no
 

I'm still a little confused sorry i was planning on running the line to the primary turbo inlet and if I do that from the filler neck and the catch can inbetween should it have a breather or no??