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GoKart and Me!!!
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Discussion Starter #1
This is another thing I started thinking about while I was bored at work...catch cans. Here's some questions:

1) What are the main benefits and do the benefits outweigh the cost? (I don't track the car, but do have the fun cruise and twistie days)

2) Is it easy to install so that the PCV and Valve Cover are vented into the can?

3) How would I route the PCV?

4) How often should it be checked for emptying? (for example, every oil change, every Xk miles, etc)

5) I've heard about these being vented to the atmosphere, how is that achieved?

6) Recommendations on brand or type of catch can?

7) Any pix of members' current catch can setup?

Like I said, bored at work, so I start thinking about some of the different mods I could do. LOL. Thanks in advance.
 

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C2H5OH
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1) What are the main benefits and do the benefits outweigh the cost? (I don't track the car, but do have the fun cruise and twistie days)
The benefits are far less to no oil in the intake manifold. Which leaves a smoother surface for air to travel along (less turbulence which lowers the Reynolds numbers) and a greater volume for the air to pass through, though very slight. The combination of the two can yield significant power gains, but only if the restriction from oil contamination went unchecked for a long period; normal gear head/car guy you shouldn't see much in the way of power gains.
Yes the benefits outweigh the cost absolute. Think of how much a can of Seafoam costs. Then figure the cost of making a catch can, which can be made for under $10. So absolutely you're ahead by having one.

2) Is it easy to install so that the PCV and Valve Cover are vented into the can?
For someone who is N/A and does not wish to draw much (if any) vacuum in the crank case, yes. Both can be routed to the catch can then to their respective stock locations.
For someone who is boosted you'd want two check valves, one on the valve cover and one in place of the PCV. Remember that the check valves will have to hold back the boost pressure. IIRC the FI guys use the Mustang SVO PCV valve and say it works well.
If you don't use check valves you must use two separate catch cans.


3) How would I route the PCV?
See above ... do you wish to draw vacuum or not? That will be the determining factor in how things are routed.

4) How often should it be checked for emptying? (for example, every oil change, every Xk miles, etc)
It will vary engine to engine. Not difficult to check from time to time and note how much you drain out. Generally though the harder you drive the more will be in the CC.

5) I've heard about these being vented to the atmosphere, how is that achieved?
IMO, by ignorance. There is no reason that a person should ever vent a CC to the ATM. The whole point of the PCV system is to draw slight vacuum in the crank case. This does a few things; it lowers the aeration of the oil, is stabilizes the rings from fluttering, it lowers the resistance of the piston in it's downward travel and it provides a tad more combustible material to the cylinders (oil vapors).
When you vent to the ATM you loose all the benefits and gain nothing. It's basically done by those who don't understand the intent of the system and couldn't figure out how to properly set a CC up.


6) Recommendations on brand or type of catch can?
An affordable route is always the air compressor water separator method. The desiccant filter in them is actually perfect for being used as a CC. I've lost the link on them but, generally they filter down to 10 micron and are rated for either separating water from air or oil from air.
Find a couple fittings and some hose and you're set. Quite sure there's a write up or few on the site somewhere.


7) Any pix of members' current catch can setup?
Sure there are, but I'm not going to search them out.
I used to have a short video of mine but it's been deleted. Also my setup is unique in the fact I draw quite a bit of vacuum in the crank case, at cruising speeds I make ~10"Hg. I used to make ~15'Hg but my cam and crank seals are leaking a bit more now.
I'm also working on fitting a GZ racing vacuum pump to my car, VP101a is the part # I'll be using. Not exactly sure what pulley diameter I'll need but I have 2 diameters for the pump and 2 for the crank. Should get me to what I want, which is ~15'Hg at all times and maybe a bit more depending on how things go.


I really hate getting technical on this subject because the lack of information has breed far too much bad information that is passed around as fact. I've explained what is correct a few times and very few have ever taken heed. So I get tired of trying to teach the correct way when no one's willing to listen.
For instance, I'd posted all the accurate information about how much air volume passed through the PCV system of the zetec (in CFM) so whomever wanted could size their lines accordingly to best ensure crank vacuum. Very few looked at the thread so those pictures where also deleted (though I still have all the information) (I may have posted all this on FJ though, I can't recall).


You can do as you wish but I think I've explained myself well enough to get my point across.
 

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ANY yes ANY vac on the crank case leading back to a Vac source brings oil to and into the intake , for boost OR na where you do spirited driving in my opinion this is a no no

You DO NOT want oil going into the intake manifold as this is the largest way to lower the octane of the fuel delivered to the engine , when you cruise around you draw hot oily full of moisture air back into and through the intake as this moves through the intake the air cools some and the deposits of oil stay and build in the intake so the next time you go WOT this oil is pulled into the engine lowering octane , this is FACT

You gain NO PERFORMANCE from having a vac on crank case on the Zetec or the Duratec engine I have tested both sitting on the dyno and pulled a hard 8 and 10 Vac on the engine and gained 0 HP or TQ

In my opinion unless your a tree hugger is to vent the valve cover and PCV to the ground and NOT back to the intake in any way , there are hundreds running this way problem free ask 030rangeSVT about this

Tom
 

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BodyKits=PantiesDrop
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I've tried both ways, venting to atmosphere and am now back to a traditional catch can setup. When I was open my car tended to stumble at low RPMs and also noticed significantly lower MPGs. On the dyno I was riching out between 4500-5500, keep in mind I was tuned with a stock PCV setup. NA motor here btw.
 

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What if you were to Put a Filter on the Cam cover vent. Crankcase vent to a catch can, then a small vacuum line to the catch can with a one way check valve to prevent pressure in the system?
 

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I've tried both ways, venting to atmosphere and am now back to a traditional catch can setup. When I was open my car tended to stumble at low RPMs and also noticed significantly lower MPGs. On the dyno I was riching out between 4500-5500, keep in mind I was tuned with a stock PCV setup. NA motor here btw.
All your issues were because either it wasent done properly or wasent tuned for it , you loose NO MPG or performance from venting

Tom
 

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What if you were to Put a Filter on the Cam cover vent. Crankcase vent to a catch can, then a small vacuum line to the catch can with a one way check valve to prevent pressure in the system?
No filter is needed on the valve cover because nothing can be sucked into the hose being as long as it is and it will be moist with oil and water inside the hose so no dust or dirt can get to the engine

Any Vac going to the engine from a catch can or pcv will get hot oily air into the intake , if your doing performance the last thing you want is hot oily air going to the intake or into the engine , vent it , I dont see the big deal there isnt a down side unless your a tree hugger

Tom
 

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...In my opinion unless your a tree hugger is to vent the valve cover and PCV to the ground and NOT back to the intake in any way , there are hundreds running this way problem free ask 030rangeSVT about this

Tom


So if I understand what you're saying, you don't recommend a catch can at all. Instead, you recommend just hooking up a hose to the valve cover outlet and running it toward the ground. And you recommend doing the same coming out of the PCV outlet. Do you recommend a PCV valve or any checkvalves? Or just drop the hoses downward with no valves?
 

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GoKart and Me!!!
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Discussion Starter #9
@ iminhell: I would like to maintain the vacuum I got going on now, which is around 15. So if I upgrade the PCV to the Mustang SVO one you recommend, that will work better for my FI CC application? Will that be the only valve upgrade I need to worry about?

Another question that came to mind this morning, the PCV hose that runs from the PCV back into the manifold, with the CC setup, I can delete that hose and just plug where it goes back into the manifold, right?

@ Tom: if you set these up to vent to the atmosphere, how do you maintain vacuum in the system?

Here's a quick diagram of how I was thinking of setting up my CC:


Thanks for the input. This is helping a lot.
 

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@ iminhell: I would like to maintain the vacuum I got going on now, which is around 15. So if I upgrade the PCV to the Mustang SVO one you recommend, that will work better for my FI CC application? Will that be the only valve upgrade I need to worry about?

Another question that came to mind this morning, the PCV hose that runs from the PCV back into the manifold, with the CC setup, I can delete that hose and just plug where it goes back into the manifold, right?

@ Tom: if you set these up to vent to the atmosphere, how do you maintain vacuum in the system?

Here's a quick diagram of how I was thinking of setting up my CC:


Thanks for the input. This is helping a lot.
if the CC is not vented, put a check valve from the CC to the charge pipe from something like a mid 90's honda or nissan. If the CC is vented, put a check valve from the Tee to the cc.

You do not want boost in the crankcase or head.
 

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C2H5OH
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Far as a check valve for boost, http://www.blastlineind.com/ProductDetails.asp?ProductCode=02PCV5-8FS-8FS

That should work. It'll definitely hold back boost pressure but I'm not sure if vacuum will suck it open (I'll try to find more data on it, like differential pressure, Parkers site's a bit tough to navigate).

I'm using a GM check valve. It was found on almost every V8 Gm from the 80's to mid 90's and most every parts store has at least one on hand, very common and cheap part. But I don't know how well they like boost ... I know I can hold back the pressure of my air compressor but I've never done any durability testing (what does high heat do to the valve?).

WD40 posted a poor man's CC thread while back, about this time last year IIRC.
I'll snap a pic or two of my setup and re-upload my data for those who want to go through it.
 

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GoKart and Me!!!
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Discussion Starter #13
Please let's keep this without any pissing contests or arguments.

Iminhell-thanks for all the input. I did manage to find a quick DIY in the SVT Performance that was made by goinloco that has really caught my eye that I am looking more into doing.
 

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A check valve from a old honda or nissan will work perfectly.

I've tested them for opening and closing/boost/vac

On vac side they'll seal shut with anything more then -1 in/hg and leaking isn't enough to record. Boost side I've had them hold over 30psi with the same leakage..not enough to record. I've tested this using a map sensor hooked up to megasquirt.

If Tom is correct that vac on the block does absolutely nothing for horsepower, atleast its beneficial to have as little as possible pressure in the crankcase. This will definately help keeping boost away.
 

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iminhell: I would like to maintain the vacuum I got going on now, which is around 15. .
WHY ?


Tom: if you set these up to vent to the atmosphere, how do you maintain vacuum in the system?
Thats the point , you dont , why do you feel you need vac in the system , In a perfect world and a perfect engine you would need the Vac most under boost when you now turning off the Vac to the crank case under boost so ???? again I ask why do you feel its needed , My opinion Vac from the crank case hurts more then it helps on a perferormance engine because of the hot ouly air it sucks to the intake , I have seen as much as a half a Qt of oil in a Focus intake on an engine running perfect with no mods

Tom
 

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2focusedracing
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I just vent mine to atmo. Two years no issues.
 

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C2H5OH
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The purple line represents the pressure/vacuum in the crank case. By design (or flaw depending on your viewpoint) there is a pressure differential because of the speed and location of the pistons. This is why the PCV was designed and implemented. It's intent is to relieve the positive pressure by using the natural pressure differential of the intake air.
If the intake manifold is at a lower state of pressure than the crank case, the intake can 'suck' (because it really isn't a suck, merely a descriptive term) the pressure out just as fast as it's being put in.
The reason there is a one way valve inside the PCV is due to WOT where intake vacuum is low or non existent. The valve can open and close to try and keep a slight vacuum in the crank case. But it can't open/close fast enough for this to actually happen. There is not a PCV in the world that can that I know of. So it's design is simply a compromise and you really don't need one.

But the valve does serve another purpose, along with it's outlet size.

To create a pressure differential you need an area (or flow) of high pressure and an area of low. Being that the intake flows more air than the crank case there is an area of lower pressure at most all times in the intake (speaking after the throttle plate).
So that's why a PCV line runs to the intake manifold post TB.

The valve and diameter act as a restrictor. In times of WOT where there is no pressure differential you can not equalize pressure by conventional means, simple high and low. In this case you have to rely on the amount of flow, intake being substantially higher than the CC. This creates a Venturi Effect and thus pressure is sucked out.


The reason for the extra breather port on the VC is to air in the Venturi Effect and just in case the bottom end becomes pressurized it has another path of escape.

*side note:
you can actually use CC flow data to find if the engine is in need of repair/rebuild. Volkswagen on newer cars has a sensor that monitors the flow though the PCV system. You can view this data and if it's out of spec (which I'm not sure what spec is) you'll know if the rings are shot or if a bore is worn, but not specifically just that you need to open it up and look. The sensor is also used with the MAF to calculate the exact amount of air being ingested. But in the case of the Focus the ingested air is only calculated by the MAF. Any extra air, such as worn rings and added blow-by, isn't accounted for, even though it has passed through the MAF once. If that's confusing, which I wouldn't doubt it is, you have to consider the time factor. Just because the air was measured doesn't mean it'll all get to the cylinder at the same time. So there may be times when more air enters and time when less does. Which will create slight rich or lean conditions.
And that is in part to why a narrow band O2 sensor 'switches'. It was an attempt to mimic the naturally occurring rich/lean conditions.

/side note



Hands on is the best teaching/learning tool. So, go out and pull your PCV out and put your finger over the hole with the engine running. Block the PCV with your other hand so the engine doesn't stall.
Feel the pulsation of air coming out?
That's exactly what the graph represents. There is a frequency to the pulsation that is very easy to figure out. It's simply the definition of frequency, Cycles Per Second. Since we know the engine Revolutions Per Minute all you have to do is divide RPM by 60 to get the frequency of that pulsation.
If your hand where more sensitive you'd be able to feel the same pulsation from the intake tube. The size of the tube, cam design and plenum design reduce the strength of the pulsations.







That's an older video but it is showing how my setup functions.

Basically I capped off the VC port, and that's it. I added another check valve, the GM one, and a catch can to filter and catch the oil. I also hardlined the PCV because I was having too many problems with rubber hoses collapsing. Used 5/8" soft Copper for the lines. Used a Aluminum water bottle for the catch can, just like the po'man thread.

It's by no means an ideal setup nor does it look pretty. It is functional though.


Time for more hands on.
Engine running, PCV back in it's place.
Try moving you boost gauge to a place you can measure the crank case pressure vacuum. The dipstick tube works well (also where the gauge in the vid is hooked to).
Pull the hose off the VC breather and put you finger on it.
You might hear a whistling. This will be air being sucked past the crank/cam seals. Won't hurt anything short term. Long term the lips of the seals can overheat and become brittle.
What's the boost gauge saying? Are you making vacuum in the crank case, you should be.
Give it a little RPM and as the engine accelerates vacuum will fall a bit. But once the RPM stabilizes vacuum should return.


Now unlike Tom, and anyone else things, a setup done this way does not 'suck' oil out of the pan. The setup is almost identical to you putting your hand over a vacuum cleaner hose. Air can be sucked out but none is allowed in. Your hand represents the crank case and the exit air represents the intake manifold.
There is no wind or pressure inside the vacuum (crank case). So the oil stays put.

Where sucking oil up comes from is air flowing through the system. More air being sucked out of the PCV than is allowed in through the VC port. It's the through air that brings the oil with it. Pass more air and you'll get more oil.



I'm kinda forgetting what I've covered and my mind just isn't concentrating on this anymore. I may of missed a few things. But I think I've got most everything covered now, the why's at least.
 

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C2H5OH
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I say no. Tom and others say yes. It's up to you as both our opinions are somewhat biased.
 
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