Vented Catch Can with Boost question
 

I picked up an ECS supercharger kit and the vendor also sent me a vented catch can to go with the kit. The ECS kit comes with a non-vented catch can. Do I just install the vented one in place of the ECS one that goes from the TB to the valley area. I'm trying to think this through. The purpose is to suck the air out of the crank case, won't the vent in the catch can supply the air instead of letting is suck air from the crank case? At WOT with the blower the one way valve closes under boost and the crank case evac is stopped, then it would make sense to have the vent to allow the crank case gasses to go somewhere. But under partial throttle it should be sucking crank case gases.

Am I better off leaving the ECS non-vented catch can where they say to install it and put this vented one in-line for the the valve cover vent that then goes to the air filter? I also need to figure out where to mount this thing. Please let me know your thoughts and what you've done or seen done. Thanks.

You can find numerous threads about this bringing up valid points for either one if you search. I personally run a vented can to prevent any potential crankcase pressure build up. I have blown oil out of the rear main before because of this which is why I choose to run a vented. I have two -10an hoses going to my catch can mounted in the passenger front fender. Each line is coming off of the valve cover. I run a line from the valley cover to the Intake with a check valve in line to prevent boost running back into the valley cover.

Someone made a filter for a catch can that had a check valve in it at one time which seams to me to be the best of both worlds.

A sealed can running to a blower or turbo inlet works well also. It’s all about what your beliefs are on which is better.

The MightyMouse can has the check valve in it. I think its the best option

The point of it running through the crank case is to cause a small amount of vacuum in the crank case. Its suppose to help the rings more stable and part of the reason why you see race cars run a vacuum pump. Part of the problem with boosted setups is they don't keep the positive crank case pressure down and cause the rear main seals to leak. With a good catch can and venting of the crank case, you will not build pressure that would damage the rear main.

I got a hold of the company that sent it to me and they said that they normally send a non-vented one, but they don't have any of those in stock. I really think I need to keep the PCV catch can non-vented so it operates similar to stock. The supercharger kit has a vented oil cap so that should help with excessive pressure.

So I'm not sure what to do with this vented catch can. Maybe its that I just don't understand how it should work. This catch can has an inlet, an outlet, and a screen between the two. With the vent on the top I'm not sure how you would ever create vacuum to pull the gasses through the screen. I could see where you could use it as a dual input to the can then vent pressure, but why would there be a screen between the two input ports? Here is a pic of the catch can. Any idea how this should be hooked up?

https://cimg3.ibsrv.net/gimg/www.cor...9b7ffd565f.jpg

Some of them do. Mines a MM can with no check in the breather.

the screen it so that the oil will collect on it and drop into the can. Best advise I can give you with installing that can is to hook the bottom port up to the valve cover and the top port to a vacuum source such as right behind your air filter right before your supercharger/turbo inlet.

So why not just block off the second port above the screen? What is the point of running it to the air filter ahead of the supercharger? If it is just for fresh air, won't the air filter on the catch can suffice? Is the connection to the main air filter it to pull the air through? There may be a slight amount of vacuum ahead of the supercharger, but not much, and any air it pulls in will get pulled in from the vent on the canister, not from the crank case. If it is to do venting won't the filter on the catch can do enough venting, especially since it is in addition to the oil cap vent?

Is there something I'm not understanding with how the setup works? Is there way more blow by than I'm thinking or the PCV needs to suck so much air the the air filter on the catch can becomes a restriction? I feel like I'm missing something in understanding how this should work.

With any catch can, you need 3 things:

1. A port somewhere within the cranckcase area to pull oil laden fumes from (can be a valve cover or the valley cover)

2. A vacuum port that sucks these fumes after they have been 'cleaned' by the catch can (this vacuum port needs to be on the intake manifold side of the throttle throttle body so vacuum is present at all times except during WOT / boost)

3. A source of clean filtered air to replace the crankcase fumes that are cleaned by the catch can and then being sucked into the intake vacuum port

NOTE: With a supercharger, a check valve would be needed in the clean side (vacuum) line (shown in green) so no pressurized air could reverse flow back into the catch can when under boost.

NOTE: In this setup, a breather / filter is installed in the valve cover for clean / fresh air to enter the crankcase ... This filter / breather will also allow air that may try to pressurize the crankcase due to piston blow-by when operating at full boost / high rpm to escape to atmosphere (saving your rear main seal)

So, in a supercharged engine, this is just one example how these lines would be routed:



Attachment 48332676

Example of a valve cover fresh air inlet filter / breather:

https://cdn2.bigcommerce.com/server2...0.1280.JPG?c=2

This site is full of bad advice on this subject. Email or call Mighty Mouse, get a setup for your goals. No reason to run a vented can on a normal reasonable street car. I don't even run a vented one on my 1000+hp car. Mightmouse cans do have a safety feature if it ever overpressurizes to vent, but most are setup to be closed loop until overpressure occurs.

Are you implying that my advice is bad ?

Some of it is. Lots of incorrect info you posted.

Ok ... So, you think what I posted is incorrect.

Why don't you take the time to draw out a nice diagram and give the OP some help with this.

As far as Mightymouse is concerned, maybe the OP don't want to spend $240 for a catch can.

BTW ... How about telling me what info that I posted is bogus

He should contact MM and get the service/support and great product.

As for you post I'll do this once because I have 5 minutes before a meeting
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With any catch can, you need 3 things: - First of all people should not be concerned as much with a "catch can" and more a complete PCV system for their motor. A catch can is just that, a can do catch stuff, and if all someone wants is a catch can, they any container that holds liquids can work. You want a complete PCV system engineered to work, flow properly, and have safety features, like a MM system.

1. A port somewhere within the cranckcase area to pull oil laden fumes from (can be a valve cover or the valley cover)
Yes you need a port, but where that port is, size of port, number of ports is all important. Just saying it can be on a valve cover or valley cover is just a fraction of the proper info. For example I have -10 ports on each cover and then a -10 port on my valley, all with special fittings for a specific application. Certain ports have restrictors such as the drivers side, or valley covers have baffles that can cause issues. Which is why this should be discussed with a person that knows what they are doing such as MM.

2. A vacuum port that sucks these fumes after they have been 'cleaned' by the catch can (this vacuum port needs to be on the intake manifold side of the throttle throttle body so vacuum is present at all times except during WOT / boost)
Depends on setup. Draft style, vented style, PCV style. All different setups with different advantages/disadvantages. You are talking about one type, one style that may or may not be best for this person. Once again, contacting a professional that sells thousands of these can get him the setup he needs for his application, not generic info that may be wrong, or maybe right. Also, saying it needs to be on intake manifold side of TB may or may not be accurate. Depends on centri vs PD blower, and the setup. Most blower setups are going to run it off the preblower inlet if a centri style, not between TV and intake like you stated.

3. A source of clean filtered air to replace the crankcase fumes that are cleaned by the catch can and then being sucked into the intake vacuum port
Once again, depends on setup and application. You are explaining to him what you did, on your setup. While that is not wrong for you, it is all general info that may not be correct for him.

NOTE: With a supercharger, a check valve would be needed in the clean side (vacuum) line (shown in green) so no pressurized air could reverse flow back into the catch can when under boost. - Depends on blower and how it is routed.

Your diagram, if not using proper lines, and restrictive parts is just going to turn the breather into a vent, and not work properly under boost.

So your info isn't per say incorrect or correct, just generic, possibly misleading, and doesn't take into account all the various setups, options, and what the OP actually wants.

Your making much more out of this than it needs to be. No matter how you slice and dice it, the crankcase vent system (with or with or without a catch can installed is a very simple system)

The diagram I posted shows the crankcase vapors being drawn out of the vent tube on the valley cover. That is because the vent tube in the front of the valley cover has in it a specific sized orifice designed to let the correct amount of metered to air pass through. It is designed for this very purpose.

No boost should be allowed to enter the crankcase / catch can system. That is why I mentioned a check valve for boosted applications ... In fact, MightyMouse also sells a catch can with a check valve built-in to the can's 'cleaned air' outlet so the hose going between the catch can and the engine's vacuum port won't allow boost to go back into the catch can when under boost conditions.

The deal is, the OP already has a catch can, and the way you make it sound is; that he needs to contact MightyMouse and let them sell him one of theirs.

BTW ... I am using a MightyMouse can on my car, but it is not the only catch can in the world that works ... You make it sound like the OPs only hope is to contact MightyMouse.

I learned a lesson here ... I am not going to respond to any thread in the future that talks about catch cans ... I will leave that all up to you. And instead of helping these people, you can just continue to steer these folks to MightyMouse with all there catch can questions. It may help there sales somewhat.

My original question is "I have this vented catch can, what can I do with it?" So basically I've gotten one answer, but when I asked why no one can explain. I guess I've come to the conclusion that the vented catch can is useless. If someone can tell me where to put it and a reason to back it up it would be helpful.

Only need a check valve for specific applications, on specific blowers. So saying blower=check valve is only right in those applications. Same thing with saying hook to valley cover, only for specific applications. For many that hole is WAY WAY WAY too small and restrictive.

MM provides excellent support. Seen way way way too many catchcans hooked up incorrectly or doing nothing, or not being used to their potential because people try to cheap out, or buy a can with no support. If he wants to just vent the crank case and doesn't mind oil smells, or a proper function PCV system, he can put on that vented can, just hook it to the crank case. If he wants a proper functioning complete setup, he needs to start laying out his application, what he wants, and then talk to someone that knows what to do. MM is one of those places, but sure he can contact CPR, or one of the hundred of other shops that do this, or make cans. Some have support and can help, others are just reselling cheap china junk and have no clue how to hook it up.

The person who decided you needed it should be able to tell you how to install it. Red flag otherwise IMO
How about the manufacturer? If they cannot say how to install it a bigger red flag.

I agree, this can should have come with instructions. But with the vast amount of knowledge of this forum I figured someone would be able to give me a theoretical reason when you would use a vented catch can like the one I received.

I've given several reasons why I think it would not work in the typical places, but I know I am not an expert. There are lots of things in this world I have yet to understand. But there is probably a reason why someone decided to build a catch can like this. I was hoping someone out there with more experinece in this area could tell me why. Then I can decide if I want to install it, modify it, or let it sit on the shelf.