Catch Can INSTALLATION. The Final Debate.

[Hard AttacK]

Originally Posted by Adam7

Mikey, you could put the breather filter on the rear as Ray and others said and put your Catch can(since you already have one) inline the pcv hose, and have best of both worlds, Zero blowby entering your engine.

I still stand by adding a can inline the pcv hose. Alot of blowby comes out of the pcv valve to the lower intake, making its way to the combustion chamber. Thats just as important to me.

Here's what im eventually doing to my bpu car and for my blow thru im doing one in line with the pcv valve and one on the rear valve cover with a breather.

[vr4tune]

Originally Posted by mikeyVR4

Damn this is a mess.

I got a email from Ray P. saying to just add a breather to the RVC and leave the rest alone. I will have to re-read this thread again. I was busy over the weekend putting my car back together and forgot about this problem.

That's all I did! No catch can just a filter instead of intake bubble.

[Import Power]

Here is my new catch can



-Chris

[mb3000]

Nice thread. A lot of various ideas, as well as applications.

Here's my take:
Stock PCV system has two vacuum sources, both of which are used during idle and other instances already described in this thread.

During idle:
-The intake bubble pulls air out of the rear valve cover, and the lower intake manifold pulls air out of the front valve cover. Drivers side fittings connect the two, and provide possible vacuum equalization.

During boost:Intake bubble continues to pull air out of the rear valve cover. PCV valve closes, to prevent positive air pressure from entering. Air must now travel along the DS tube, in order to evacuate from the front valve cover.

Popular catch can locations for lightly modified vehicles seems to be after the rear valve cover, where all air will be leaving the ventilation system during boost. Some seem to experience problems relieving pressure, and vent to atmosphere via filter or external dump.


IMO for a lightly modified (daily driver) car it would make sense to run two catch cans, in between each PS valve cover, then to each respective turbocharger intake piping tract. This system would cap off the lower intake manifold connection entirely. This would allow the same amount of air to enter the engine at idle (those who argue the PCV valve regulates the correct amount of air could even leave it in place). Pressure would still be equalized via the DS connection.
The main benefit would be 2x the ventilation capabilities vs. the single vent from the rear valve cover, and also clean(er) air being recirculated into the intake via the catch can (vs no catch can). Possibly allowing cars that were forced to run without vacuum at idle due to venting issues, can now have vacuum at idle and still vent a satisfactory amount of pressure.


Cars like Chris' are on a whole different level!

Please excuse my high resolution picture, artistic paint drawings, etc...

[Adam7]

Originally Posted by mb3000

Nice thread. A lot of various ideas, as well as applications.

Here's my take:
Stock PCV system has two vacuum sources, both of which are used during idle and other instances already described in this thread.

During idle:
-The intake bubble pulls air out of the rear valve cover, and the lower intake manifold pulls air out of the front valve cover. Drivers side fittings connect the two, and provide possible vacuum equalization.

During boost:Intake bubble continues to pull air out of the rear valve cover. PCV valve closes, to prevent positive air pressure from entering. Air must now travel along the DS tube, in order to evacuate from the front valve cover.

Popular catch can locations for lightly modified vehicles seems to be after the rear valve cover, where all air will be leaving the ventilation system during boost. Some seem to experience problems relieving pressure, and vent to atmosphere via filter or external dump.


IMO for a lightly modified (daily driver) car it would make sense to run two catch cans, in between each PS valve cover, then to each respective turbocharger intake piping tract. This system would cap off the lower intake manifold connection entirely. This would allow the same amount of air to enter the engine at idle (those who argue the PCV valve regulates the correct amount of air could even leave it in place). Pressure would still be equalized via the DS connection.
The main benefit would be 2x the ventilation capabilities vs. the single vent from the rear valve cover, and also clean(er) air being recirculated into the intake via the catch can (vs no catch can). Possibly allowing cars that were forced to run without vacuum at idle due to venting issues, can now have vacuum at idle and still vent a satisfactory amount of pressure.


Cars like Chris' are on a whole different level!

Please excuse my high resolution picture, artistic paint drawings, etc...

I like it, but I have a question. On the pcv side where your running the hose to the intake rather then the lower manifold, would that change anything being that the connection is made before the throttle body rather than after? Would the pcv still function as it should with proper vacuum?

[mb3000]

That's a good question. IMO if many recommend keeping the rear VC connected to the bubble for VSS sealing at idle, it seems logical to me that moving the PCV connection to the intake piping would be sufficient.

Obviously you're going to make sure that your intercooler/intake system is a leak-free as possible, as the efficiency of this system will go down as vac leaks go up.

[sensational980]

Can someone tell me if this works.

Heres my setup here in pic. I put the krank vent on front from pcv.

Then installed Catch can on rear to open breather.

Is that right or should I be doing something else?

I have the bubble still and plugged the holes. I have dejon preturbo pipes and will be using them as soon as my couplers come. They do not have the port like the bubble does.

[Forest Gump]

Originally Posted by sensational980

Can someone tell me if this works.

Heres my setup here in pic. I put the krank vent on front from pcv.

Then installed Catch can on rear to open breather.

Is that right or should I be doing something else?

I have the bubble still and plugged the holes. I have dejon preturbo pipes and will be using them as soon as my couplers come. They do not have the port like the bubble does.

That will work, but I have a few comments.

1)I have found those specific 90 degree fittings on that catch can to be restrictive. Replace them with straight barb fittings (you can get them at a hardware store) 1/8" npt to 3/8" barb IIRC

2)You can vent that, it will cause a small amount of air to be drawn in that is unmetered if you are draw through, but since you are blow through it should be okay. Either way it isn't something you can't tune around.

[sensational980]

So as far as the valve stem sealing I take it this is not an issue? Also this 2nd bigger krank vent I just leave off correct?

Originally Posted by Forest Gump

That will work, but I have a few comments.

1)I have found those specific 90 degree fittings on that catch can to be restrictive. Replace them with straight barb fittings (you can get them at a hardware store) 1/8" npt to 3/8" barb IIRC

2)You can vent that, it will cause a small amount of air to be drawn in that is unmetered if you are draw through, but since you are blow through it should be okay. Either way it isn't something you can't tune around.

[Forest Gump]

Having the rear line vented will not remove the vacuum caused by the pcv valve. I ran that way for a bit and had no issues.

Yes, I would leave the big krank vent off.