Oil Catch Cans

[Midnight R33]

Im looking to buy an oil catch can for my RB25-DET and have seen a few different styles and methods of installing.

I have seen two different types. The sort with the breather on top and then the ones without.

i have been told that if you plug both hoses from the rocker cover to the can it causes pressure imbalance and pops the dip stick out, but i have seen this done successfully before.

I have a mate who has his hooked up with one hose going from the rocker cover to the can and then the second hose from the can to the pipe that recirculates back to the intake i think. But i have heard that this method doesn't optimize the breathing capabilities of the engine.

So if anyone knows what the best way is, please help me.

[RANDY]

I have mounted mine up the 2nd way. It's a JustJap one like the above, so there's only one in, one out.

I've run it off the manifold side (off-boost) and inline like you described. I'm not sure what purpose it'd serve to run both rockers into the can though? If you had a can with 4 nozzles, then you'd run both sides independently.

i.e: manifold to can to rocker. Then on the other side: turbo side to can to rocker. That covers ALL breathing, whereas the above can would only over you for one or the other. (on boost breathing or off boost breathing)

http://srandy.com:81 look at the catch can install if you like.

[The Dan]

If you ever need a catch can then I would recommend an engine rebuild coz if you have that much blowby, you're gonna need to do something.

[Scribble]

What about catch cans that drain back to the sump?

[The Dan]

A catch can that drains back to the sump? you might as well leave the setup the way Nissan designed it.

The only way you are going to ever need a catch can is if your rings are phukt so why bother with one?

[unarmed_skyline]

do they even do any preformance for you??? does helping the crankcase breath help in any preformance way or are catch can's mostely done for looks???

[RANDY]

neither, they are designed to help filter out oil particles in the air that comes out. The air makes it back round your intake system, including front-mount.... the less oil you have in all that, the better your system will cool the air.

It may only be a fine film of oil, but the hot air won't conduct through the oil and onto the surfaces of the intercooler as efficiently as if there were no oil in at all.

[The Dan]

neither, they are designed to help filter out oil particles in the air that comes out. The air makes it back round your intake system, including front-mount.... the less oil you have in all that, the better your system will cool the air.

It may only be a fine film of oil, but the hot air won't conduct through the oil and onto the surfaces of the intercooler as efficiently as if there were no oil in at all.

<{POST_SNAPBACK}>

This is also true. They still have a very large portion of wank factor to them. For them to be legal they have to be able to contain 3/4 of your engine's total oil capacity so anything less than a 3 litre one is a waste of time.

[Midnight R33]

Thank you Randy for pointing out to the not so educated people what a oil catch can does your spot on the money. And thanks for the help.

Whats the point of buying performance parts if your not going to protect them and look after them.

And 3lit3 32. I think you should probably learn a bit more before you start dissing poeples ideas!

[The Dan]

Thank you Randy for pointing out to the not so educated people what a oil catch can does  your spot on the money. And thanks for the help.

Whats the point of buying performance parts if your not going to protect them and look after them.

And 3lit3 32. I think you should probably learn a bit more before you start dissing poeples ideas!

<{POST_SNAPBACK}>

Ok I'll go read some more books and learn heaps more about catch cans and crankcase ventilation.

I wasn't dissing anyones idea and I am sorry you feel that way. You need to understand that a catch can is not going to benefit you in any way other than saving you from cleaning up a mess in your engine bay when the engine goes bang. If you are worried about oil fumes getting into your inlet (which you cannot stop no matter what you do) then block off the return pipe to the intake before the turbo and buy a $16 two inch air filter to put on the rocker cover in its place.

Bottom line is this......

You can go out and buy a catch can if you like. Doesn't matter which one, they all do the same thing. It will be illegal to have it fitted if it is not at least a 3 litre capacity. If you ever need one it's because your engine has gone bang and you will need to rebuild it but more and more I see people with catch cans who seem to think they are some kind of engine saving device. Just because the oil didn't spray everywhere, your engine is still ok and you continue driving it until more damage is done to other engine components.

I personally think they are a waste of time. I'm glad you have been informed by people who know what they are talking about.

P.S. Before you tell someone to go learn something, do a little research into their background. I don't appreciate it.

[Busky2k]

I never found sticking filters on the rocker cover did any good, cos they saturated with oil pretty quickly.

The first picture is basically a filter, that goes in line between your rocker cover and the turbo. It filters out any fumes so cleaner blowby gases go into the turbo. However it doesnt solve the PCV issue, as oil still gets into the intake manifold/valves etc.

The second picture is designed not to go in line, but actually divert the blow by gases into the bottle and out to atmosphere. I use this one and I prefer it, cos that way, there is guarantee of no junk getting into your intake. However if you go this way, you have to block the PCV or you will have big vacuum leak because it pulls air through the rocker cover at idle and light cruise.

Edited November 15, 2005 by Busky2k

[RANDY]

Midnight, you're welcome mate... I could see that noone was really giving any explanation as to its use.

elite: I can see your point too, but I really don't want anyone to think that I installed one purely because it was shiny.

If mine catches some oil, then i'll leave it in place. I'm about to change my intercooler over to an R34 unit, so if there is a substantial oily film through my intercooler, then i'll know that it WILL make a difference. If the can does nothing at all for me, then i'll just remove it.

Anyways... take it easy on each other guys. Everyone has their own preference. =-]

[Midnight R33]

Hey thanks a whole heap guys

I think i'll go with the open ventilation type to make sure no dirties get back in.

So Busky how did you go about blockin off PCV?

Oh and Elite sorry for bein arse. You've left some pretty good feed back from my reading, and i dont want to hold a grudge with a fellow Skyliner.

[RANDY]

What a classy guy. =-]

[The Dan]

Hey thanks a whole heap guys 

I think i'll go with the open ventilation type to make sure no dirties get back in.

So Busky how did you go about blockin off PCV?

Oh and Elite sorry for bein arse. You've left some pretty good feed back from my reading, and i dont want to hold a grudge with a fellow Skyliner.

<{POST_SNAPBACK}>

No worries mate. Sometimes I come home in foul moods and don't really put much effort into actually helping people. I read back through my posts and realised I should probably just pull my head in.

Pulling head in.........now!

[RANDY]

LOL =-]

[JimX]

No worries mate. Sometimes I come home in foul moods and don't really put much effort into actually helping people. I read back through my posts and realised I should probably just pull my head in.

Pulling head in.........now!

<{POST_SNAPBACK}>

Hehe, I was thinking of asking why all the hostility but you answered it above before I asked!

I have a catch can. Not to save my engine, but to try helping prevent the recirculated oil from coating the entire length of my intake. As it is it's doing a fair job, after about 30k km you can see that there is a slight brown smudge on the rocker cover hose outlet (it's translucent) but on the intake side the hose is almost entirely clear as it was when new. That indicates to me that the can is stopping some or most of the oil from coating my intake and intercooler. I feel that I should replace the can with one that can take a whole bunch of steel wool to help trap more oil, but there's so little blow-by it's not a high priority for me.

I'm not thinking that this thing will save my engine at all, or render the car street legal, but I do think it's a pretty cheap mod to help ensure that your intercooler maintains its efficiency. Autospeed have a couple of articles on how to build an air/oil separator and the reasons behind it (that's where I read that the steel wool is a good idea) so there's more than a few people who think it's of some use.

Oh, my main motivation in doing the re-routed plumbing is that I used to just have a breather on the rocker cover, and it essentially started to coat the inside of my engine bay with oil.