CantSeeMe

An observation I've noticed is that alot of the 1jz and 2jz GTE single turbo engine bays have catch cans. But I don't see it as often in the Na-T setups......I'm just wondering why that is?
I have a pretty good idea of their function. But Im trying to decide if there is there a significant benifit to warrant adding 1?
Or are they just mainly there to look pretty?
There is a substantial range cost for a semmingly simple device IMO, just how big of a difference is there between the ones ive seen for $30 and the ones for $300 ?
Any thoughts or suggestions are much appreciated!
-Thanks

2jzlex

iTrader: (3)

CantSeeMe:

Everyone has there own opinion about oil catch cans, and there are multiple ways to set them up. Depending on your view of their function, dictates just how you set them up.

One view is that oil catch cans are there just for that sole purpose, to catch oil vapors in a seperate container that can be emptied when you wish. By using bigger lines from the valve covers into an open container, it merely gives the oil a place to accumulate. The debate with this is that it doesn't actually help relieve pressure from the system.

Another view is that oil catch cans can be used to catch oil vapors before recirculating into the intake by a vaccuum source. By using vaccuum, it is thought to help relieve pressure in the crankcase. So you are creating a system that does the exact opposite of a PCV valve, it is constantly attemtping to relieve pressure instead of opening when pressure becomes to high. The problem people have with this is that if the majority of vapors aren't seperated from the air recirculating back into the engine, they can gum up all your piping, intake manifold, etc. But the main concern is that having oil vapors in your intake charge can lower your octane rating, thereby increasing the chance for detonation.

There is another way to set it up also. People will actually direct the lines from the valve cover into the exhaust, and use all the exhaust flow to help draw that pressure out of the motor. As the exhuast flows out of the dp, it draws those vapors with it and out the exhaust. But alot of people dont recommend this as you have to be running some serious power to make enough draw to do any good. Regardless if it does or not, it eliminates the need for a can and simply lets it go out the exhaust.

Now, if you do research on some of these cans, you will notice that some are "baffled", these are for recirculating the flow back into the intake. There will be two connetors on top, and one out the bottom. Some just have the two connectors on top, these are for just catching the oil.

Alot of stock systems have some sort of plastic container, and a small vaccuum line that routes it back into the intake. On boosted cars, it is always compressor, or on the pipe between your filter and the compressor side of your turbo. They were made to help relieve pressure, but after awhile people started figuring out all the downsides of doing this. So the ideal setup, is to figure out a way to run it back to the front side of your turbo, but make sure that close to all of the oil vapors have been removed as to not cause all the forementioned problems.

Hope that helps
Jon

vipsoarer

Jon is correct in saying everything that he has said but a big piece was left out. Oil from the pvc system actually reduces octane points when introduced to the system. Running a fully functioning pvc system is good for emissions since it burns off the vaporized oil but when you are tuning on the edge of detonation you want your fuel to have the full octane rating instead of losing anywhere from 1-3 points from the extra oil in the intake. plus it keeps the motor cleaner on the inside like Jon also stated.

2jzlex

iTrader: (3)

Come on now VIP..... Someone with your status and knowledge should know that everyone is really concerned with emissions..... jk. All we are gonna do now is confuse the poor guy with things that he doesnt care about. lol.

On a serious note there acually are people that purposely leave the PCV valve in place for various reasons. But none that would really need to be considered or of importance more of just personal preference.

Jon

Blk97SC300

iTrader: (4)

emmissions isn't in my vocabulary. I live in CA, and I have no problems passing a smog test every 2 year

I have a oil catch can in my car- it's been installed since May and I havent even filled up ¼ of the can yet. It's probably not even necessary, but it looks kinda cool . I dont want any of that crap being put back into the turbo or intake system .

CantSeeMe

Thanks for all the info everyone, I appreciate it.
Hey Jon,
To be honest, I had no clue there this much discussion about this or so many different views on this topic. I just thought catch cans had little function, and were primarily there to look shiny and pretty!
From your reply though, i could see i was wrong and needed to do some research ...... So I spent 1/2 the night last night going through catch can threads on SF.
Now i think i have a better idea of their function. And an idea of what i will do......
But you know i'm highly concerned with conforming to emmissions here in Cali too! ...... Seeing as we already have this cali **** gas out here, I'm thinking diluting it further is the way to go!
-Thanks again
-Will

2jzlex

iTrader: (3)

Not a problem man. In theory the best route is to make it more of a filter using the vaccuum source(preturbo) to help relieve crankcase pressure. Kind of what you are thinking. In BlkSC300's case, all his is there for is to catch the oil vapors, not really provide any actual function. I mean, you could use a popcan and run the lines into that, it would actually serve the exact same purpose of the way he has it set up now. No downplaying intended there guy, just merely stating the facts. You can actually have one made with a custom design that would have a real function for probably half of what you would by just a polished can for(unbaffled). You can create your own design of a can that you could have some kind of filter element in, say.... some scotch pad, pretty popular choice. With this in mind, just figure out a way to take the can apart so you can change it every once in awhile, but make sure that it gives a good seal when put together, or bye bye filtration.

I am actually trying to design a can that swirls the incoming air into kind of a vortex state. By doing this, the weight of the oil vapors in the air would actually seperate onto the side of the can and then funnel into the scotch pad. If I can figure this out, I will try to do a writeup on it and you guys can tell what you think.

Jon

vipsoarer

Jon, your right, what the heck was I thinking?!? The last thing I should be concerned about is emissions, i mean my state doesnt even check for it except some towns out in bfe, nor will anyone care about passing on this board since id say about 90% of us wouldnt pass if our life depended on it. ha ha

either way its a good idea to run one as it gives you all the potential of your gas. Check out www.honda-tech.com for all of the possible ways to build a catch can. Some are really nice while some are the soda bottle idea like Jon said. No matter what people say, the honda group has a rare few that know how to be baller on a budget while keeping function of the parts through the roof.

dumdumgreg

iTrader: (5)

people, if you got pics of your setup, post them up

Also had a questions about this
the fitting on the passenger side cover is the one that leads to the catch can, but the fitting on the drivers side valve cover is connect to the manifold...
why is that?

2jzlex

iTrader: (3)

More than likey that is the side that has the PCV valve.

dumdumgreg

iTrader: (5)

So the side with the Purple L shaped fitting can be disconnected from the intake and routed to the oil catch can as well?

dumdumgreg

iTrader: (5)

Man, I have yet to see a pic of someone connecting up hoses from both valve covers to an oil catch can on a 2jz.
tough I have seen a bunch with Nissan silvia motors....

2jzlex

iTrader: (3)

You haven't seen too many 2j's then.... go to SF and search for stuff on catch cans. You would get enough to take up about half your gig on your computer

To answer your question dumdumgreg, if someone is going to go the route of putting an oil catch can on their car, they pretty much just take out the PCV valve. I mean if the point of a catch can is to relieve the max amount of pressure possible, then having a valve in the way kind of defeats the purpose.

Jon