Since the release of our Oil Catch Can we have had a lot of questions about how our set-up functions. Most understand the basics of what the OCC does, but want to know more about how our OCC does it.
The Basics
For the last 20 or so years, all cars have had some sort of PCV system installed to re-burn unwanted vapors from your crankcase instead of venting them to the outside world. This system is based on a vacuum. When the engine is running, the pistons are happily moving up and down. There is a small amount of compression that is lost into the crankcase passing by the rings. This excess air will cause pressure in the crankcase to slow down the pistons from going up and down and build up oil vapors that create frothing of the oil. There are also small amounts of condensation that get trapped in the crankcase and you don’t have to be a rocket scientist to know water and oil don’t mix.
An oil catch can is designed to “catch” unwanted vapors that are in your crankcase and PCV system and prevent these contaminants from entering your motor. With no catch can install, you have the potential to get build-up in the intake manifold causing dirty valves and poor compression.
How the Mazdaspeed 3 PCV System Works
A Mazdaspeed 3 has two PCV lines. One goes from the cam cover to the intake and one goes from the crankcase to the intake manifold. Why the two locations you ask? Well, they go to the closest vacuum source, but in a turbo car, you will not have a vacuum when you are in boost so a check valve closes and stops the crankcase from being pressurized and boost being lost.
Improving the Design of the CorkSport OCC
Most Oil Catch Cans include a PCV valve in the set-up for turbo vehicles, as ours did until just recently. So why does CorkSport no longer have a Check Valve on our Oil Catch Can setup? This is a great question.
We noticed that by adding the PCV check valve to the oil catch can, the OCC worked less effectively because when the check valve closes (the car is under boost) the catch can is no longer able to do the same job of “catching” the vapors. When your car is under boost is the time the catch can is working the hardest to prevent those contaminants from entering your engine. Instead, it is just sitting there waiting for the PCV valve to open back up.
We decided to cap the intake manifold and pull the vacuum through the intake so both cam and crankcase vapors are trapped in the OCC leaving your motor the cleanest it can be. Now, the CorkSport Catch Can will be working to eliminate those vapors all of the time without the restriction of a PCV valve to prevent it from being able to remove contaminates while your car is under boost.
So why not cap the intake and the intake manifold and have it vent to atmosphere?
There are several reasons this is a bad idea and being friendly to mother nature is only one of them. Yes, you might sleep at night better knowing you are not hurting the environment but this is not the only reason to plumb the catch can back into the intake.
1. The intake vacuum helps draw vapors out of the motor by creating a low-pressure system to force the vapors out. Without the vacuum, the vapors can only be forced out by the pressure in the crankcase. This is unreliable and inefficient. Think of how much easier it is to get air into the motor under pressure (ie turbo). It only makes sense that the opposite would be true about getting it out and it would be much easier to achieve under vacuum.
2. Metered air passes through the MAF sensor before entering the engine, then a small amount is passed by the rings and enters back into the intake or intake manifold. If you do not route the PCV back into the intake manifold then that calculated air is “poof” let out into space causing your fuel trims to be off.
If you think you can tune around this you are correct, sort of. As the rings degrade you will have a small amount of additional air passing by the rings. Time to re-tune. The rings degrade some more, then time to re-tune again. I think you get the picture. Eventually, you forget to keep up on this and your fueling is off enough to cause a check engine light or worse. Zoom-Zoom-Boom!
This is the nature of a MAF-sensored car. There is a good reason that Mazda has everything hooked back up to the intake. Your car will be happier, in the long run, doing this.
Awesome info, thanks for the write up!
This is a great write up but what I would like answered is what sets your OCC apart from the competition. What to look for and what not. Love your products.
Other OCC’s on the market incorporate a check valve into their set-up to avoid over-pressurizing the can. This makes the OCC work less effectively because when the check valve closes (the car is under boost) the catch can is no longer able to do the same job of “catching” the vapors. The CorkSport Catch Can has been designed to work without the PCV check valve so it works to eliminate those vapors all of the time without the restriction of a PCV valve to prevent it from being able to remove contaminates while your car is under boost.
Can you explain why most other OCC offerings incorporate a check valve and many seem to think it’s a good idea to have it so the OCC and crank case isn’t preasurized under boost? Just trying to understand the difference 🙂
Sorry, that comment come off as if I hadn’t read the article, which I did LOL Just wondering why some maintain that it’s needed. That’s all. I plan on picking up the CS OCC myself either way 😀
Brydon,
If I understand things correctly, this solution puts both the crank case and cam case under constant vacuum. Would this cause an inflation of results by creating an environment that invites additional leakage into the various cases and potential for a more rapid erosion of rings?
No worries! When we released the product, we were incorporating in a check valve for turbocharged cars as well, but after additional testing and R&D we found a more effective solution. My only guess is that other companies have gone through the additional testing and R&D to find a more deliberate way to get better results from the installation of the catch can. There is nothing wrong with using the check valve method, this is simply a design improvement.
The crankcase and cam case are already connected all the time. That is how oil leaks down from the head back into the pan. This does nothing other than allow the vacuum source to be present at all times instead of relying on the cam case vent to do all the work while in boost. If anything it would lengthen the life of the rings by cleaning out the crankcase better and allowing the pistons to move up and down easier. On large turbo setups you can actually have the dip stick pop out because of the pressure in the crankcase. Makes for quite the oil mess. At a certain point the cam case vent by itself cannot keep up with the increased pressure. The new OCC setup allows more vapors to be collected and will be sufficient for small to large turbo setups.
A little late from me but, Thanks for this article, very informative!
Brydon,
Isn’t the tip vacuum Port where the blow off valve vents to? So when your shifting the catch can would be pressurized?
Great! now I can choose another tube color while upgrading, I also did brake my crank case breather on the first installation, I assume that i’m not alone on that, but what reason did you guys send a new one btw?
The PCV of Gen1 and Gen2 are different. How does this factor in to your setup?
We are only offering the silicone in black now. We switched to a reinforced silicone to avoid tearing which was occuring occasionally when the clamps were over tightened on the blue and red silicone.
Since we are removing the PCV altogether the difference between the gen1 and gen2 does not factor into the set-up.
Wouldnt this design prevent the windage recirculation that the PCV valve is supposed to create? I know people have complained about the factory PCV valve leaking up to 2 or 3 lbs while under boost in the manifold, but I think mazda did this on purpose in order to create a wind flow in the crankcase. Other high performance supercharged applications use this type of design, (Rx Can i think makes one for the LS chevy motors with this inmind) In other words, when under boost, the pcv valve will leak 2 lbs or so as tested and confirmed by bnoon and others on MSF; the purpose is to push the small blowby out of the crankcase (in order to keep your oil pan from absorbing them) while at the same time (under boost) the vacuum source becomes the valve cover pulling the forced blowby out. So the contaminants that seep through the rings will be forced out through the factory PCV valve and sucked up through the valve cover WHILE UNDER BOOST! I know it’s been debated over the purpose of the mazda pcv system and how horrible it was initially, however I think they meant well by it. Obviously once you turn up the boost you may have to modify the PCV system to help vent the extra pressure. My question is… Have you guys considered the adverse effects of eliminating that windage recirc? Dont get me wrong, I love your oil catch can! It’s one of the best designed catch cans I’ve ever seen! I love them so much I decided to put two on my MS3 and am going to buy some for my mustang GT as well! LOL I will send you guys pics if you care to see them after the install. Enough ranting…
Hi can someone tell me which oil catch can is really good for mazda 3 1.6 diesel please thanks alot.
I want a response to this please, this guy stated some of my similar thoughts and would like to know the facts on the corksport end. By the way everything on my car is corksport except for the mounts and accessport, everything else is for my, so I love the products. Just wish they had more.
Hi I recently purchased a corksport catch can, and i do love it as I do all the corksport products i own. But im running into an issue, my compression is good hasnt changed at all. Before I put the catch can on wasnt experiencing any oil issues like this either. But now with the catch can on, it seems im experiencing so much vacuum i guess that its pulling oil out if my crankcase into the catch can and depending on the speed and boost i am at it pulls more oil. Really don’t wanna have to pull the catch can off.