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:

 

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

 

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??