Catch Can Debate

[Calum]

Originally Posted by ANTI_LAG

If your boosted then there will not be any vacuum under boost so the Oem style Pcv system will not function.

Originally Posted by wootwoot

Interesting. Never thought of that. So if you are running forced induction there is no vacuum under boost. Does that mean the PCV will ever shut? Or will it always stay open?

My next question is this: Where it the PCV valve? And how does it work? That is, what causes it to close/open?

We are doing good here guys. Keep it up.

Boost is pressure above atmospheric conditions. Vacuum is pressure below atmospheric conditions.

I agree that when there is positive or even neutral pressure in the intake manifold the oem style PVC becomes next to useless.

The question though, is how much time you spend with anything other then vacuum in the intake manifold. The best, or at least the easiest, indication that you're spending most of your driving with the intake manifold under vacuum is if your power brakes still work. The power assist for the breaks comes from intake manifold vacuum.

Just because the turbo or supercharger is creating pressure in the duct before the throttle body doesn't mean that pressure is also in the intake manifold. If it were the engine would be uncontrollable.

[Sportsguy83]

Originally Posted by Calum

I think this thread has taken a turn for the worse.

[ANTI_LAG]

Originally Posted by Calum

Boost is pressure above atmospheric conditions. Vacuum is pressure below atmospheric conditions.

I agree that when there is positive or even neutral pressure in the intake manifold the oem style PVC becomes next to useless.

The question though, is how much time you spend with anything other then vacuum in the intake manifold. The best, or at least the easiest, indication that you're spending most of your driving with the intake manifold under vacuum is if your power brakes still work. The power assist for the breaks comes from intake manifold vacuum.

Just because the turbo or supercharger is creating pressure in the duct before the throttle body doesn't mean that pressure is also in the intake manifold. If it were the engine would be uncontrollable.

Okay this is my last post but boost is measured in the intake manifold, not in the piping. Not really sure what you are saying. Alright I'm out of this thread, its going in circles.

[JP]

Originally Posted by wootwoot

Your can could possibly get the car impounded in CA. Depends on the mood of the cop that night. Nothing against your amazing can. That's just the facts over here in my communist state. They are very stringent with emissions stuff. No cats could also do it. Illegal intake as well. They usually give fix-it tickets but sometimes things go real bad. There is a member on this forum that almost got his car taken due to having a breather tank when he was coming home from the track. Luckily he disconnected it before he left the track. Crazy...

I was planning on having everything in the car I needed to take the can off or disconnect it should I be pulled over. I would only need some pre-cut hose and maybe a pair of pliers. I think it would be a good bargaining chip if you ever got popped. Especially for driving too fast.

Venting catch cans aren't road legal in Australia either. The system has to be closed and plumbed back to the manifold/intake.

[Dezoris]

Let me see if I can help end this discussion or at least provide some factual information with a source, Toyota itself. This also applies to almost every other engine maker in the modern world.

Attached Below is an SAE Article on the purpose and functions of a variable PCV system and how to trouble shoot problems with it.

I know some of you have seen my DIY for the Radium can.
http://www.ft86club.com/forums/showthread.php?t=21079

As anti-lag stated, I personally don't care which can you choose as long as you understand how they work and which cans are BS.

I want to clear up and actually post some info that can help put some of these debates to rest. The reason for many of these threads is because no one ever gives a definitive answer to questions.

FACTS:

• The FR-S/BRZ has 1 PCV valve, not two.
• 70% of the contents of blow by gases is unburned fuel not oil
• The PCV valve runs from the backside of the engine to the intake manifold and this is the system that IS under vacuum (READ PDF)
• The tube running from the front of the engine to the intake is the breather tube this tube is not under vacuum.
• 80-90% of all blow by gas is routed to through the PCV valve to the intake manifold. This is where you will collect the most amount of oil, unburned fuel and water vapor in a catch can.
• The breather tube is for excess blow by not routed through PCV only under high load, namely in forced induction.
• If you are NOT running forced induction, running a catch can on the breather tube is basically useless.
• Blow by gases increase in a linear fashion based on engine load. (Lower Load = Less | Higher Load = More)
• If you drive for efficiency (low engine load) blow by will be minimal and thus a catch can on either the PCV line or breather line would catch little to nothing.
• PCV Systems including vacuum are integral part of engine design and included in air to fuel ratio computation by ECU/ECM.

CATCH CAN SYSTEMS:


OPEN SYSTEMS:
Cans that do not route PCV gas back into the intake manifold.
Anti-lag has a specifically designed open catch can for turbo setups which benefit from having an open system. It is perfect for those who do not want any type of oil or blow by gases back in the intercooler or intake.
However depending where you life you may fail emissions inspection if they find you are venting PCV gases into the atmosphere.

CLOSED SYSTEMS:
Radium, and several others provide systems that sit in between the PCV valve and the intake manifold or in between the breather line and intake.
These systems hooked up correctly, do NOT bypass the PCV system, they run inline. However the cans must be drained periodically to prevent over flow or plugging the PCV system.

CLOSED LOOP SYSTEMS:
Basically this covers the Crawford Can, it sits between the PCV and the breather tube, and separates the air and oil back into the block. The concept is you put the blow by gas and oil back into the engine without having to drain a can. The problem not even addressed by Crawford is, blow by gas is oil, fuel and vapor that is blown by passed the rings thus contaminated. In a true performance setup do you want contaminated oil back into the block?

DIFFERENCES IN CANS:

Baffled or Condensors
Cans that use condensers or baffles help to take the blow by gas and help condense oil and prevent it from just flowing right back out of the can into the intake manifold or intake.

Unbaffled
Cans with a straight open design with an inlet and outlet port.
These cans are basically the cheapest and least effective at trapping/separating oil, fuel and moisture. Without a baffle system there is nothing to help separate the oil from the air.

AOS
Air oil separators that use special channels to help separate the incoming air vapor into "clean" vapor and oil back into the block/oil?

[Calum]

Originally Posted by ANTI_LAG

Okay this is my last post but boost is measured in the intake manifold, not in the piping. Not really sure what you are saying. Alright I'm out of this thread, its going in circles.

One would hope. But I couldn't figure out another way to have a boost gauge indicate anything other then vacuum at cruise.

[wootwoot]

Originally Posted by Calum

I think this thread has taken a turn for the worse.

LOL... Amazing quality is what I meant. The function is still under debate. I'll edit my post accordingly.

[Dezoris]

Originally Posted by wootwoot

LOL... Amazing quality is what I meant. The function is still under debate. I'll edit my post accordingly.

The catch cans will help in primarily two ways:

1. Reduce oil/fuel vapor back into the intake tract which reduces carbon build up on valves and piston domes. (Not eliminate) Carbon build up is a major maintenance and performance concern on direct injected motors. The FA20 also has port injection and this will reduce carbon on intake valves.

2. Reduce potential of foul up inside intake manifold over time.

For forced induction models it does the following:

1. Eliminates oil inside the intercooler which hurts performance efficiency increases heat soak.

2. Eliminates contaminents inside intake tract from breather blow by. (Running two cans)


As for which can works? Look for threads or videos showing peoples results not just sales pitches or pics of pretty installs.

[Tim_Asphalt_FRS]

Originally Posted by ATL BRZ

I run a Moroso





Internal baffling, easy to drain, no rattles.

This picture, posted by Crawford Performance is why I installed one on my BRZ. They pulled apart a low mile FRS to find oil on the pistons. The car was still N/A as far as I know, but it had apparently been run very hard, but it was still enough to warrant the small cost.

Where did you get the Moroso catch can for the FRS/BRZ. I don't see anything vehicle specific, mostly just WRX/STi stuff.

[ATL BRZ]

Originally Posted by Tim_Asphalt_FRS

Where did you get the Moroso catch can for the FRS/BRZ. I don't see anything vehicle specific, mostly just WRX/STi stuff.

http://amzn.com/B004K9BIY4

[wbradley]

I dont know, it looks like the Moroso is hooked from the front crankcase vent to the intake before throttle body when its the PCV vent to intake manifold that gets most of the blowby gas on a NA car.

The Cusco has Japanese instructions that seem to indicate this hookup as well according to the pictures but I thought it was wrong and hooked from PCV to intake manifold inlet under the crab plastic.

[ATL BRZ]

Originally Posted by Dezoris

FACTS:

• The FR-S/BRZ has 1 PCV valve, not two.
• 70% of the contents of blow by gases is unburned fuel not oil
• The PCV valve runs from the backside of the engine to the intake manifold and this is the system that IS under vacuum (READ PDF)
• The tube running from the front of the engine to the intake is the breather tube this tube is not under vacuum.
• 80-90% of all blow by gas is routed to through the PCV valve to the intake manifold. This is where you will collect the most amount of oil, unburned fuel and water vapor in a catch can.
• The breather tube is for excess blow by not routed through PCV only under high load, namely in forced induction.
  
• If you are NOT running forced induction, running a catch can on the breather tube is basically useless.
• Blow by gases increase in a linear fashion based on engine load. (Lower Load = Less | Higher Load = More)
• If you drive for efficiency (low engine load) blow by will be minimal and thus a catch can on either the PCV line or breather line would catch little to nothing.
• PCV Systems including vacuum are integral part of engine design and included in air to fuel ratio computation by ECU/ECM.

Guess I need to redo mine then... thanks for the info... I was wondering why I hadn't caught anything in around 800 miles of spirited driving... DERP

EDIT: FIXED! Took like 10 minutes and just reused what I had, just had to trim a the hoses a bit.



Doing it right!


now using the rear pcv instead of the front breather


Tidied up

[mad_sb]

Originally Posted by wootwoot

First: Not sure how I feel about the sales pitch in the thread... But I don't own the thread so I guess I can't say much about it. Am I wrong in thinking it isn't the best form?

I will say ANTI_LAG brings up two good points:

1. Catching blow by from the front AND rear PCV is a good idea and something very few catch cans accomplish. You need one purpose built in this way, a dual can, or two single cans to do this. This is a must for turbo/supercharge guys.

2. He also brings up the debate between open and closed catch cans: I myself am a proponent of closed systems and have never, until today, found anyone that was in favor of opening the PCV system (with the exception of racing applications). Even looking at Radiums sight it says: "Radium Engineering does not necessarily condone an open PCV system, however, there are many applications that demand this setup."
It goes on to say:
Open PCV System Advantages:
Completely eliminates any chance of oil vapor returning into the intake air stream and collecting in idle air control valves, intercoolers, etc.
Required for specific applications. For example, a race car using a turbocharger system without a compressor inlet pipe.
I believe one of the disadvantages is that the open system brings in un-metered. I think I have read that it also, in essence, creates a vacuum leak as the system is now open to the atmosphere. Perhaps someone (ANTI_LAG?) can describe the benefits of an open type catch can? And, specifically, why it is better than a closed system?

IMO the benefit of a closed system outweighs the drawback.. the reason for the catch is to separate oil vapor out of the vented gas.. When you start talking about forced induction i think people forget you have an excellent source of vacume when under boost... that is your air intake in front of the the turbo.. When not in boost, the intake manifold itself becomes the vacume source.

The best you can ever hope for with a vented system is not building positive pressure in the case... with a closed system you can pull a vacume on the case at all times.

Also, theory aside, the majority of the open system is saw on the dyno when i did tuning work were messy (blowing oil vapor out the filter under boost), some would pop dip sticks from excessive crank pressure, and some (on cars that were not speed density) would have fuel trim issues based on how the owners installed the systems.

Here is the Saikou Split DC3 Catch Can Set that i ran on my ralliart and am about to install on my FR-S:

The can on the right hand side connects the intake pipe to the valve cover the can on the left connects the valve cover to the intake manifold with a pcv / check valve combo that closes as soon as the manifold goes into positive pressure. During off boost conditions, the vacuum is stronger in the manifold and the port that connects the right side valve cover vent to the intake pipe acts as the breather tube and allows fresh air to be drawn in and swept through the crank case. During boost, the check valve closed on the manifold side and the tube that connects to the intake pipe now acts as the vacuum source that pulls a vacuum on the crank case.

Of the two cans, the one on the intake manifold catches the most oil (about 4X more than the one on the intake side) since most of the time the engine is running in vacuum... this also explains why 4B11T's like to det on cylinder #3... the port on the manifold dumps right into cyl#3.

[King Tut]

I went vented: