View Full Version : Concept of PCV system canister

10-09-2006, 06:44 AM
I have been thinking about making a PCV system canister that would trap oil from both valve covers as well as allow for the PCV valve and breather line to still be used. Here is a copy of the email I sent to Canton Racing:

My name is Eric Hokanson and I am a member of the SCMC (SVT Cobra Mustang Club). Many of us in the club have been discussing the concept of improving the PCV system and thought that you may have something to offer. The concept of the PCV system improvement would utilize a breather tank similar to that of the #23-030 or #23-031 tank with a few modifications. The tank design should have two ports in the bottom portion so that both valve covers could be attached to the catch can. The upper portion will have the same baffle design but would not use an air filter on the top. Instead of the air filter element, the top portion of the tank will have an aluminum screw on chamber which is sealed with an "o" ring for easy removal for cleaning. The top chamber should also employ two ports, one on the side for the connection of the breather line that connects to the intake pipe, and on the top of the chamber a mounted PCV valve. Inside the chamber there should be a foam element to act as a filter.

The main objective of the canister would be to prevent oil from entering the intake plenum and still allow for hydrocarbon fumes to pass. The issue with the current PCV system used on the DOHC motors is that large amounts of undesirable oil passes through the PCV line and breather line which leads to issues in the long run such as increase in carbon fouling in the combustion chamber, pools of oil in the lower intake plenums (the issue is compounded with the supercharged models since this tends to clog the intercoolers). Many have used air/oil separators (designed for air compressors) on the PCV line but this places undesirable restrictions on the PCV system which tends to lead to more oil passing through the breather line.

I would like to hear your thoughts on this concept. Would this even be feasible or too much trouble since it would have to remain EPA compliant?

If they do not respond to the email, I will send the same to Cobra Valley, Moroso and others that make similar products for breather tanks and catch cans.

What do you think about it? Any suggestions would help.

10-09-2006, 06:49 AM
Eric, that is way cool! I hope they respond because it's an issue all Cobra drivers need to be aware of and all would respond positively to a design made through a Cobra owner's request.

10-09-2006, 07:00 AM
I think I will not wait for them to reply and send the same message to Cobra Valley since they do alot of custom work to start with.

10-09-2006, 08:12 AM
Probably a good idea...whoever comes up with it first gets the sales!

10-10-2006, 06:48 AM
Apparently it is not much of a good idea after all. Here is the reply I got from Cobra Valley.....

I understand your dilemma, which is shared by many, especially the 5.0
Mustang crowd who shared this problem in the 90's, and still do.

That much hose for the vented air to travel through would be fairly
resistive to the low pressure PCV system unless using extraordinarily
large lines... such as 7/8" I.D. at a minimum.

It would be far better to "filter" the oil from the air at the engine
rather than pulling it into the can y a remote location. Once the line
saturate with oil it could attract more oil filling the can far before
it may otherwise do. Creating a fine mesh screen on the underside of the
valve cover going to the PVC is the best way, much like water being
spayed into a screen door rarely gets much farther inside the house and
just runs down to the floor.

We would not be able to make an EPA licensed product without getting a
C.A.R.B. EOC number which would be about in the$10,000 just for the
The cost for the C.A.R.B. EOC number is relatively high but I would venture to guess that the EPA license is much higher. I can understand the cost since I get involved with UL listings with the products I design which is about the same.

Hopefully the above response has given some insight to what would be needed to reduce oil passing. I have thought about the mesh and almost used stainless screening but found once it was cut, small parts of the screen could possibly fall into the valve cover and that is not something I would want. Best alternative is an aluminum patterned sheet metal which would not fall apart like a screen. The SHM filter does work on the Breather line but would not fit in the PCV location due to it's size. A smaller version would be ideal, and Billet Flow had one but could not find it on their web site.

10-10-2006, 07:11 AM
my bad....:D the PCV pre filter is on the JLT website, not the billut flow.


Using this part and the SHM breather filter, should reduce oil passage as well as reduce the amount of paracitic lines that would influence oil flow like in the use of the air/oil separator.

Oh well, at least it was worth thinking about it even though it would have not worked as thought.:doh2:

The reason the breather canisters exist is that they are required for racing application and are mandatory equipment for NHRA, as well as other associations.

10-10-2006, 07:21 AM
So, this pre-filter still traps oil, but before any more resistance losses occur in the tubing. Does the pre-filter knock oil back down into the valve cover, or trap it inside, like the air/oil separator?

Also, is the SHM breather filter similar to the air/oil filters? If so, are you suggesting to use it inline with the pre-filter or separatley on the passenger side valve cover?

Hmmm, I wonder if the pre-filter fits on the passenger side?

10-11-2006, 07:07 AM
I will provide the link for the SHM (sean hyland motor sports) breather filter which fits directly into the valve cover on the passenger side. It is too large to fit on the drivers side valve cover. The JLT pre filter is best suited for use with the PCV valve. I have the SHM breather filter and it is a nice part. I replaced the plastic fitting with a brass fitting since I had trouble using the stock rubber hose with it. There are two metal screens with a filter element sandwiched between them and if the oil enters into it, it will drop back down into the valve cover.


The Jlt pre filter is similar to that of the SHM but it is smaller in size. By the looks of it, it is basically a cylinder with a metal type filter. Both the JLT and SHM parts are not catch cans since they will not hold oil like the air/oil separator since they return it to the valve cover. I would not doubt that you could use two of the JLT pre filters, one for the PCV and the other for the breather line since both openings on each valve cover are the same size.

What I like about the SHM breather filter, you can open it up and pack it with a different filter element. However the cost of the shm part is a bit over twice the cost of the JLT part. The question is simple, do you have enough clearance on the passenger side for the larger filter? Also, if you compare the plastic insert on the breather line to the size of the PCV valve if they are relatively the same size the JLT part should work on both valve covers.

All I need now is the JLT pre filter for the PCV valve.

I may not be fully convinced that the canister idea would not work, but why go to the trouble and cost to find out. I would rather start off with something that has been proven first.