KingSpence

Here's the deal, My SR has a vent port from the back of the block, tying in with the "T" on the head vent, then running to a catch can. With the way the new turbo/manifold/downpipe fits in the car (ae86) I'm tight on space, and am wondering if I can leave the block ventilation port breathing on it's own to atmosphere, and run a line from the head ventilation down to my catch can, then up to my intake from there.

Long story short, getting a hose from the block vent port to the catch can is a pain, I'm feeling lazy. If it's not going to damage anything, and it's not going to puke oil I'd like to just leave it to atmosphere.

jr_ss

Cap it off or plumb it in, do not leave it open to atmosphere, as you're asking for worlds of trouble. Here's a good thread with some decent information. Perhaps a setup in there will suit you.

http://zilvia.net/f/showthread.php?t=235851

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KingSpence

So by capping it off, everything can vent from the valve cover without causing pressurization?

CarRamrod

For the PCV port on the valve cover, you need to recirculate it back into the intake.

The common misconception for this is that venting it to the atmosphere is fine. However, this is not the case. Pulling a vacuum on the crank case is beneficial in a lot of ways. First off, it helps seal all the gaskets, it helps seal the piston rings and it also pulls harmful contaminates out of the crank case. These contaminates and vapors are a by product of burning fossil fuels. They are corrosive and harmful to the metals in your engine including the bearings and also contaminate the oil. Not properly ventilating the crank case means faster break down of engine oil and premature engine wear.

The best way is to run a catch can setup to catch any oil vapors as they pass through it so they are not introduced to the intake system. Oil has an octane of like 50 and it'll cause smoke and detonation or (ping).

Do not cap the PCV port off. You will pressurize the crank case which could cause leaks due to seals being pushed out.

If you have anymore questions then ask away. I'll help as much as I can.

CarRamrod

Also, if you're pulling vacuum from one port on the motor and then leaving another port open, you're causing a vacuum leak.

Just run them both to a catch can and then to the intake. It'll pay off having done it right the first time.

Kingtal0n

Or avoid a catch can all together. A catch can is only for when the engine explodes magnificently. Otherwise, its just "extra plumbing" that will lower the overall pressure drop experienced by your crank case.

If your engine produces so much vapour oily mess that you actually require a catch can just to run the car, then either you rebuilt the engine wrong (typical, actually) or it's very high mileage and nearing the end of it's service life, or the rings are toasted from poor tuning. Or there is an issue with a check valve.

edit: spelling

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CarRamrod

All this is not true lol.

Not trying to start anything but just saying you might wanna do some research.

Let's not take things to extremes.

Yes if you're filling up catch cans with oil then you obviously have a ring issue but a little bit of oil over time in the catch can is normal.

Capping off the PCV port will cause crank case pressure, especially on a boosted motor. Piston rings are not a perfect seal.

Here is the deal, most people look at these purpose built racecars and don't see a catch can on most of them. Those cars are only run for short periods of time and generally the oil is changed after each racing event. On a car that is driven regularly, it's best for your engine to run a proper PCV system for the reasons I listed in my earlier post.

I'm of the opinion that you should put forth the effort to do things right the first time to benefit your motor and piece of mind for yourself. But that's just how my opinion.

supersayianjim

interesting I will start running a catch can setup and will report back with my findings.

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KingSpence

I rebuilt my SR last winter, had my crankcase vented block-->head "T"-->catch can to atmosphere. In 8000kms I had no oil whatsoever in the can. The can was mounted low in the engine bay as well.

Kingtal0n

You are contradicting yourself, first you said proper PCV system like factory, then you said catch can- which is no longer proper PCV. No factory engine comes with a mile of extra plumbing with a can in the center for catching oil. If anything there is a return style to push liquid oil back into the pan. There is no place for vapors, they go "wherever they want" i.e. into your compressor wheel, or into your intake manifold. Or they seep out from between clamps. Or they get pushed out of fittings or seals. Or you breath them in.


Point out one thing i said that wasnt true. Just one thing
You are simply not familiar with my style because you are new. Ill forgive you but try not to take the internet too seriously.

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genericforumname

Call me crazy (no expert on s13's) but doesn't the s13 have a Catch can stock? Wasn't this why they changed the valve cover design on the s14 to help remove the need for a catch can?

hobbs

Uh huh...

Not only did all of nissans highport DET motors come with an inline air/oil separator, lowport DET motors have them build into the valve cover and USDM DE motors have the same air/oil separator. Regardless if they are plumbed back into the pan or left to collect and be drained by the user they still serve the same purpose and they are all catch cans.

Catch cans are always a good idea on motors that experience higher than OEM boost levels and capping a valve cover vent is never a good idea. A well thought out PCV/catch can setup will go a long way.

Kaifd3s

What happens if I have a line connected to the intake, goes through a catch can, and then connected to the right side of my block (S14SR). Then plug off the pcv and plug up the line on the intake manifold. I mean it will have vacuum from the intake, and also I am leaving the line connecting the block to the valve cover.

Would this work?

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CarRamrod

Proper PCV system can include a catch can. A factory PCV system + a catch can is an even better option than a factory PCV system that does not include a catch can. Remember catch cans CATCH all the crap you don't want in your intake that a PCV system without a catch can wouldn't. So I'm not sure how that's contradicting myself but ummm ok. Haha.

Lots of cars come with a factory catch can lol. You serious? That return style system is a return style CATCH CAN that just simply returns any oil caught by the can to the oil pan and then vents off the vapors on top using a 2 way valve. I'm not a fan of this style setup but it works. Again, do some research.

I'm new to this site but not to engines. Just because I haven't been on Zilvia.net for years doesn't mean I know nothing about cars or how they work.

+1 for this comment. Good info right here.

I'll need to see pics of what exactly you're talking about and from there I will help as much as I can.

ixfxi

^ This man is right.


^ This man is wrong and really has no clue what he is talking about.

I've had a catch can on one of my cars for years now. I added it on the PCV side of the system and it works wonders. Every time I change my oil I empty the can. There is always a fair amount of "shit" -- thats really the best and most technical description I can give it. Its brown sludge that does not resemble oil. I am very happy that its not in my intake system.

As for the non-PCV side, I currently have that left open on one of my cars - and not by choice. I have had a tough time finding the proper fittings. Essentially, that should be plumbed into the intake after the MAFS and before the throttle body.

Kingtal0n

The oil doesnt sit in a can, waiting for the operator to empty it out every so often, the way aftermarket cans are intended to be used. Big difference between hands free operation and aftermarket toilet bowls. You are simply calling the oil pan a "catch can" what difference does it make if the oil breifly passes through a hose or object? Thats like saying my valvecover is a catch can, because the oil briefly passes through it.

hey guys my turbocharger oil feed is a catch can because the oil breifly passes through it.

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Kingtal0n

The word PCV means "positive crankcase ventillation" There is no "catch can" in the word PCV nor is it implied or necessary.

Kingtal0n

So, what "crap" Is it you think a catch can is catching? And why don't factory engines include owner empitable cans if they are catching all that "crap". If you do not define the word "crap" you are ignorantly assigning a blanket word in place of real knowledge. Is crap a solid liquid or gas? Is "crap" an acid? What is the PH of this crap and how is a catch can able to catch it? If you think oil leaving the valvecover is crap explain why.



Exactly. Nothing is being caught for the owner to empty out at a later date. Therefore, not a "catch can" by definition. Calling the oil pan a catch can is irrelivant. Think before you type.

CarRamrod

Who cares where the vapors and oil that a catch can catches sit? As long as I don't have them in my oil, crank case or intake, I'm happy. So what if you have to drain it out once in a while? If you're running a custom setup like a SR swap for example and you don't want to have to work on it then I suggest you go buy a Honda accord. I hear they have great warranties.

Toilet bowl is a perfect description for a catch can. It catches all the shit you don't want in your motor haha.

Ok, now you're just plain reaching here. Arguing that a PCV system doesn't function better or the same with a catch can or that it isn't proper when you add a catch can is just ridiculous. A catch can is an added layer of protection.

Why not tell people to not upgrade their exhaust after adding a bigger turbo? Sure a bigger, more efficient exhaust isn't required but it will improve the over all performance of the engine after the larger turbo is added. Same with the PCV, we are adding a part that isn't required but recommended to improve the overall functionality and improving protection to an expensive motor.

Bottom line is a properly set up PCV system with a catch can IS an upgrade to your engine. There is no arguing that. I've listed the reasons in my earlier post.

If I can answer any more questions then please let me know.

hobbs

You really should.

The stock SR20 air oil separator and a catch can serve the same basic purpose is to collect (IE catch) oil from the crank case vapors to prevent them from entering the atmosphere. Your whole argument that a catch can has to be emptied by the user and the stock oil air separator does not is nothing more than an attempt at trying to make an argument out of nothing.

They share both the primary function of separating oil from vapors and if you're so inclined to do so you can have an aftermarket catch can return the oil to your sump.

Kingtal0n

Ok, it seems as though you lack science. A vapour, is a gas. A gas is not going to be caught in a catch can. A gas will pass the can and be recycled back into the engine. You cannot "drain a gas from the catch can once in a while."

furthermore, an SR swap is not a "custom setup" it is a stock engine, from a stock car. My 1999 S15 silvia is all original and there is nothing custom about it.



very scientific description there, "shit". please define "shit" because right now you are only imagining "shit" in a can somewhere. If there is any "shit" coming out of your engine, I would be worried.

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Kingtal0n

It does not catch anything if it recycles back to the oil pan. Whats the difference between a hose and a can, if both simply recycle back to the oil pan? If the can doesnt actually CATCH anything, how is it a catch can?

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Kingtal0n

Please see my previous quote where I did add this fact of "extra layer of protection" :

Annd... thats all its good for. catching gobs of oil or debris in the event of catastrophic engine failure. simply catching oil and NOT returning it to the oil pan is silly and reduces the overall pressure drop where it counts due to the additional volume of unncecessary plumbing. And thinking that a catch can will "catch gaseous vapours" is just ignorant.

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hobbs

I was going to argue with you but after seeing your location I realize it's nothing more than a waste of time.

Kingtal0n

YOU were going to argue that a device that doesn't catch anything can still be called a catch can? And then you realized how that would sound, so you decided to blame my state?

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hobbs

No, I'm just not putting in that much effort to talk to a brick wall.

You're trying to get into the nitty gritty about the definition of the word catch. Use whatever word you want, the function remains the same, removing oil from vapors that come from the crank case. Catch, retain, remove. It's all the same shit, you just seem to be hung up on a single word to try and prove your incorrect point.

Kingtal0n

Catch, retain, remove. None of those things describe a factory "oil separater". Try again.

The function of a catch can is not to remove vapours, as previously discussed, a vapour is a gas, and can not be caught in a can.

You may find that as your progress in a scientific manner, words do actually matter. Schools do not allow the words intercellular and intracellular to both mean the same thing.

The scientists who do not get nitty gritty about details make big mistakes. A random example would be the chirality of molecules, a left handed version might cure a disease, and the right handed version might cause birth defects.

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hobbs

The oil never changes state, it is still a liquid, thus can be caught in a can, regardless if it's the OEM catch can or aftermarket catch can.

CarRamrod

I agree with you, you can not catch vapors or gasses in a can.

Maybe the problem is that you don't understand how a proper catch can setup works. Allow me to explain, generally speaking and this is just an example of one style catch can, you have a dirty side and a clean side. The clean side is generally on the top of the catch can. A foam or mesh separates the clean and dirty sides of the can. The "crap" is pulled to the dirty side and vacuum is pulled from the clean side. The clean side is routed from the can to the intake. So as air is drawn up from the dirty side, it passes through the mesh and or foam which catches the majority of the "crap" and it falls to the bottom of the can where it is stored until you drain it out. The air that has now passed to the clean side may still be contaminated by some unwanted contaminates and is sucked up into the intake where the motor burns it up in the combustion cycle and it's pushed out of the exhaust.


A PCV system without this can will route everything directly to the intake and contaminate your intake and valves much faster with "crap".

I hope that makes things more clear for you.

I can define the "crap" or "shit" if you'd really like me to but I don't feel that's the point of this thread. I believe we are informing the OP of what he should do for his particular situation. But if you don't know what all is in this "shit" or "crap" then please let me know and I'll break it down as best I can. But "shit" and "crap" basically say all that needs to be said about it.

It catches the oils and vapors before it gets into the intake system. No one said this way is the beys or most efficient way. Just another way to skin this cat.

hobbs

And since we're getting picky about wording, never once did I say removing vapors, you should look back at what I had posted.