Infiniti FX Forum banner

1 - 20 of 35 Posts

·
Premium Member
Joined
·
201 Posts
Discussion Starter #1
So over the past few years of FX ownership, I've experimented with a few oil catch can designs. I'm currently on my fourth OCC, but feel like I have finally figured it out for both NA and FI applications on the VQ35DE. I've put together what I wish I had when I first started reading up on the OCC and all the different ways it can be used.

First, let's start with what an OCC is and why it's a good thing to have.

The VQ35DE engine (and the majority of other modern engines) employ what is known as positive crankcase pressure. This comes from the fact that the combustion process inside your cylinders leaks a little. The piston rings have a gap in them and blow-by gasses push through these gaps and up into the valve/rocker covers. The blow by gasses are comprised of everything that the gasses come into contact with along the way. Air/fuel mixture, exhaust gasses, oil and a small percentage of coolant as well. Oil is usually the highest contributor to blow by gasses.

The OEM design vents these gasses out of the valve/rocker covers through the passenger side PCV valve and the driver's side valve cover vent, located under the Throttle Body. In addition, the two valve covers are connected by an interconnect hose to make sure the pressure inside each valve cover stays equal. See find #1 (three locations):



The two valve/rocker cover outlets are routed back into the intake tract, so that a vacuum is pulled and the gasses flow back into the plenum to be burned in the cylinders. The only problem is that these gasses leave a trail of sludge behind them. If you have ever opened up your plenum, you see the oil stains and sometimes even small pools of oil inside the plenum. This is the definition of where oil sludge comes from.

Here's a diagram of the OEM system under your hood.



Now obviously the manufacturers don't consider this to be a threat to the long term reliability of the car. Yes, it's a little messy over time but there is no immediate danger to the car or any of the systems. After a lot of miles, the intake would need to be cleaned out. Not doing so would begin to rob you of efficiency (mpgs). So installing a catch can on a stock VQ engine is only going to be a "nice-to-have". Not necessary, but appropriate for FX enthusiasts who want to go the extra step for their car.

There are actually quite a few ways you can attack the install. This was one of the things that was very confusing for me because everybody seemed to have a system that was different from everybody else. I've sketched out the most common designs, and I have recommendations for which ways are best and why.

First up is what I would recommend for any NA FX of any generation. Both valve/rocker covers hoses are routed to the catch can inlets and a single vacuum sources is hooked in, allowing you to cap the other vacuum port in use with the OEM setup. I purposefully used the larger 5/8" hose attached to the intake tube for the larger diameter, instead of using the smaller diameter hose as the vacuum source. This is my number 1 recommended setup. It uses the OEM size fittings and hoses.



Here's a photo of the above design in action in my FX. The circled area is showing where I capped the vacuum port on the plenum.



Photo from the other side of the OCC. The vacuum hose is routed to the driver's side...



And it attaches to the port on the intake tube.



These next options are really variations on the same theme. This one uses the smaller hose as the vacuum source so IMO would not be as ideal. Would probably still work just fine and might be the way to go depending on where you plan to place the OCC in the engine bay.



This method uses a T-fitting to join both valve cover outlets into a single source for a can that has only one inlet. IMO this is too restrictive. I did try this for a while and could actually hear the system sort of "depressurize" as I turned off the car.



The next variation is actually two OCCs - one for each side. This would be my second recommendation for any generation FX in terms of cost. It would be my first choice for the best performance/efficiency setup.



Finally, there's a breather setup. Not CARB or emissions legal, but common with Forced Induction platforms, which have greater blow-by in general. This setup includes drilling out the PCV for free flow (removing the one way valve).



This is my current breather setup, for use with a Forced Induction platform. I'm using brass breathers rather than the normal air filter media breather you might see.



Another breather setup I really liked (also on a forced induction motor). This one has the air filter media breathers.



So now you know what an Oil Catch Can does and how it might be installed. What are the important things to remember about selecting a can and the rest of the parts?

Restrictions are bad. The smallest opening in the system is what limits the flow of gasses to the can. Pick a can that has fittings matched to your hoses - or larger. This is also a reason I didn't like the T-fitting options. The T-fitting itself is a restriction as well as reducing two hoses into one.

Taking this vent concept to the extreme - I have seen OCC setups that add two to three more vent lines off each valve cover, insuring free flow. The OCC has 6-8 inlets and then either a vacuum source or a breather. Example:

http://www.t1racedevelopment.com/index. ... -cans.html

http://www.t1racedevelopment.com/index. ... h-can.html

I have seen several installations that use one OCC on only one side of the engine. This means that the other valve/rocker cover is still being evacuated into the intake tract. You are still having a positive impact overall but that's only half the job. Depending on which side you use, the PCV valve might actually help or hinder the ability of the OCC to do its job. I would not recommend doing this and it is why I did not include a diagram as an option. I did actually run this system as well, just on this one side. Doing this on BOTH sides would be absolutely ideal. Would have been easy to add a second can but I ended up going a different route.



Catch can filter methods and effectiveness -The way each can's design captures the oil (suspended in a gas) is pretty much key to using the system at all. There are four common catch methods:

1) Gravity. The theory is that the oil/contaminants are heavier than air and as the air passes into the larger volume of the can and slows down, the oil collects on the sides and bottom of the can before the air passes into the vacuum source outlet.

2) Baffles. This is pretty much a gravity system that has plates or baffles set up inside the can so that the air has to slow down and move around them. Oil collects on all surfaces and drips to the bottom.

3) Filter media. DIY people use Stainless Steel pot scrubbers or screens. There are some OCCs that have dedicated filters or mesh that can be removed and changed out.



4) Breathers. These cans usually employ one or all of the first three methods before the breather allows the clean air to escape into the engine bay. If the can is not effective at doing it's job, the breather itself is a last line of defense and will saturate with oil and/or oil will collect on the closest items in the bay. Sort of counterproductive to keeping a clean bay but none of that is going back into the engine, which was the point of the install.

So the design of the can is important. The eBay specials can be small, often restrictive, have leaks... been there, done that. Plenty of guys DIY the whole can - lots of threads out there on the subject.

If I had to pick a can for the NA FX, it's the black can installed in the photos above. Saikou Michi Co, Modified Stage 3 OCC with custom size and oriented fittings for no extra charge.

http://www.saikoumichi.com/951_page.htm

Here's the modified version I ordered, based on where I was placing it in the bay.



Feel free to post up your own OCC photos and experience!
 

·
Premium Member
Joined
·
4,763 Posts

·
Premium Member
Joined
·
10,642 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

GixxerSteve said:
Here ya go ----> viewtopic.php?f=62&t=802. Page 3.
Nice yea we were talking about them that far back jeez i cant believe its been that long...

Good thing you added "oil catch can" in your title- I was ready to talk choppers
:lol:
 

·
Premium Member
Joined
·
201 Posts
Discussion Starter #4
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

GixxerSteve said:
jumbosrule said:
Feel free to post up your own OCC photos and experience!
Here ya go ----> viewtopic.php?f=62&t=802. Page 3.

Nice clean install - I remember seeing this thread. This is one of the designs that only covers the PCV side of the rocker cover. Any plans to add another can to the other side?
 

·
Premium Member
Joined
·
10,995 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

Thanks for a great post... btw, where did you get the hosing?
 

·
Premium Member
Joined
·
201 Posts
Discussion Starter #6
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

DatMan said:
Thanks for a great post... btw, where did you get the hosing?
I guess this is a key part of the system. Here are my favorite websites for parts.

I have purchased parts from this site several times. This is where my silicone hose came from.

http://www.siliconeintakes.com/

And I really like Spectre's selection of modular parts.

http://www.spectreperformance.com/#CATALOG

More often than not, I find parts in one of these two places - then go order them for cheaper off eBay. Make sure you know what you are buying tho - it's easy to get crap quality if you miss the fine print. Pay attention to wall thickness and both inner/outter diameters of the hose.
 

·
Premium Member
Joined
·
10,995 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

Thanks for the links!
 

·
Registered
Joined
·
9 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

Based on the amount of info you posted the experience you have with modifications is great !
Have some questions.
-Did you observe any excessive oil consumption in any of those engines?
-How many miles are typically on those cars?
-For those of us that do experience excessive oil consumption, connecting the drain of the oil collecting device to the
Dip Stick sleeve opening, may work to return that oil back to the crankcase, or its a bad idea?
-Is there another PCV valve between the passanger valve cover and the hose leading to the air intake?
-If not, why use PCV Valve at all, when half of the engine works without it ?
And finally, do not get upset from this one, why you need more power from this powerfull engine, can you handle it ?
Is'nt the car spinning its rear wheels when pressing on the accelerator?

LW
 

·
Registered
Joined
·
9 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

Already ordered one Oil Catch Can via the internet and expect to install it within one week.
Mine is a G35 MT6 Hi Rev engine, known for oil problems.
However I got more info on this site than on the G35 one, so I am back.
Hope you are still on the web looking for questions and answers.
My G35 start using excessive oil around 25,000 miles (its 2006). At 29,000 I took it to the dealer for oil consumption test,
but he (the dealer) tricked me by filling it up before he called me in to observe the Dip Stick. (I know that because I took pictures of the Dip Stick one hour before I went to the dealer and 10mm of oil was missing !)
Asked Consumer Support to give me another dealer which performed another trick.
After filling up with fresh oil, he sealed the Dip Stick with a plastic tie and told me that I am not suppose to check the oil until 2001 driving-miles.
After the 2001 miles when I came back, he opened the seal with me present, but ony 8mm oil was missing!!.
That ment that they overfilled it at the fill-up and that's why they prevented me from checking it?!!!
So now I am conducting my own tests to see if I need to sell the car or keep it.
I know this my be the wrong forum, but the PCV valve and oil collection was one of the items I was thinking about when I saw all your modifications.
What are your thoughts about this matter!?
 

·
Registered
Joined
·
9 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

Does any one knows what are the Manufacturer's specs for compression test of an Unmodified VQ35DE-High Rev Engine???
 

·
Registered
Joined
·
9 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

Seems that no one is monitoring this section or site anymore !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 

·
Premium Member
Joined
·
10,642 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

wechslerl said:
Seems that no one is monitoring this section or site anymore !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
wow patience! We cant keep up with your posting frequency :D some of us have jobs during the day.... :p

Did you read the forum rules/faq section for instructions how to post pictures??
 

·
Premium Member
Joined
·
10,995 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

wechslerl said:
How do I paste a picture of my home made oil trapper here ??
When you made your OCC did you go by this thread? Or the DIY OCC thread posted by Steve?
 

·
Registered
Joined
·
9 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

I do not remember where I saw the web site for complaining to the Government about this, because I am member on several clubs, like: Maxima.org, Altima, FX, G35 and 350 ZX, they all have reported oil problems.
For now, @ 32,350 miles on the odometer, what I know for sure is that the only difference between the high rev engine and all the rest is the computer controlled intake cam shaft.
The computer decides to retard or advance the opening of the intake valves, but the actuator is done via oil pressure.
Also noticed that the vacuum on IDLE on the PCV valve side is such that it flattens any air hose, except the thickest ones.
This also explains why so much oil is being sucked into the chamber, but it does not explain (yet) why it goes pass the rings so early, since those are no different than all other engines.
Therefore, I conclude that the vacuum created by the variable intake, is causing such a strong vacuum that the piston rings are running without oil !!!!!!!!!!!!! and that's why they wearing out so fast.
I started using lucas last week to improve cylinder walls lubrication.
LW
 

·
Registered
Joined
·
4 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

Guys,
Thank you for the great information you posted regarding Oil Catch Can, Oil/Air separator. your information has helped me tremendously in order to install my Oil/Air Separator. As I want to use a dual system, I am still trying to figure out where to place the second separator for the air intake-throtle air flow. For right now I would like to share my photos with you all.

Thanks

Nissandro
 

·
Registered
Joined
·
4 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

[attachment=0:10smwfrx]P5190004.jpg[/attachment:10smwfrx]Guys,

I want to show and share with all of you how I used the good information from "Jumbosrule" about using two Oil Catch Cans, Oil/Air Separators. I have to say that I did some research and came to the conclusion his approach makes a lot of sense. On a previous post I showed where I put my first OCC. I was also asking for a possible place to place the second one. After considering several places within the engine bay I found a place in front of the engine. This is a place where my OCC looks factory. You will see that I didnt change much of the OEM arrangement in the engine bay. I am sure the pics are self explanatory but if you have any questions just ask.
 

Attachments

·
Registered
Joined
·
28 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

I know this is an old thread...

A key piece of the PCV system is that it draws fresh air into one valve cover via the intake tube and pulls the 'dirty' air out the other side thought the PCV valve when vacuum is high. Without having fresh air flowing through the engine, the PCV system is effectively just a crankcase vent.

Make sure when you do your catch cans that you still have flow through the crankcase. Seperate cans on each side are almost required, capping off either side of the system is bad.
 

·
Registered
Joined
·
4 Posts
Re: Definitive OCC thread; aka Oil Catch Can, Oil/Air separa

CBR Worm,

Thank you for your feedback.
I still have flow through the crank case. I agree with you in that capping either side of the system is bad. In my case I did not cap any of the hoses that come in and out the valve covers. The air-oil separators were placed considering the direction of the air flow the comes out of the PCV and the direction of the air flow that comes out of the valve cover on the driver side into airflow intake.

One interesting thing I noticed is. The air oil separator that I placed by the PCV fills up with oil after a while. The one I placed en between the valve cover (driver' side) and the airflow intake does not get any oil at all. I'd like to hear your thoughts.

Thanks again.

Nissandro
 
1 - 20 of 35 Posts
Top