Oil catch can

Joined
15 November 2006
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Location
New Orleans
So when and how much crap do you empty out of there?

I've emptied mine randomly but for the first time didn't touch it for about 2500 miles. I had about 1/4 of a cup of gunk.

I've read climate has some factors and there's others, but I've been driving in some rain, temperatures averaging around 40 and running 5w30 oil. About to switch to 5w40 though
 
I remembered with my bbsc ....emptied mine after above 2k it wasnt very full. That was with a trip to texpo from charleston,sc..I just put one back in my car (turbo)..maybe 500miles..just checked it..two nights ago..nothing in it. Running 10w30
 
There are a lot of variables. Not all catch can setups are equal, and may not allow as much venting/release of pressure/oil vapors etc. Then there are the different conditions of the motors(stock low mile, stock high mile, buily tight, built loose etc). Then differnt power levels, amounts of boost(higher pressures) etc. Then there are different driving styles/levels/amounts of hard driving. And then there are different oil weights and/ or conventional oil vs. Synthetic.

Its not going to be easy to directly compare and deduct anything from it, but could give you an idea of where you stand vs. Other FI NSX's.
 
Interesting, I was basically going to ask the same question. I've run the spectrum of having to empty the catch can as frequently as right after a day of spirited driving, to many months and thousands of miles in-between. It seems there are numerous variables at play, and the ambient conditions seem to be a big one. It helps to have a sight glass to check your catch can.
 
FWIW, I have just over 3K on my BBSC setup I installed this year. Catch can is hooked up to the rear valve cover only...lots of spirited driving and 1 track day on it. Nothing in the catch can so far that I can see. At least nothing up to the bottom of the sight glass yet.
 
How do you have yours ran? Mine runs from the PCV to the can to the throttle body. Breather filter on the vent.

3.0 motor BUT I have the 3.2 valve covers which were bought from the BBSC days to stop the oil blurp with the older valve covers..
 
Been looking into this lately and see mixed reviews to keep or remove the PCV. Any thoughts?

I do like Stevelee's design. Just not sure I like the self-draining feature yet.

CIMG6426.JPG
 
How do you have yours ran? Mine runs from the PCV to the can to the throttle body. Breather filter on the vent.

3.0 motor BUT I have the 3.2 valve covers which were bought from the BBSC days to stop the oil blurp with the older valve covers..

If you're asking me then it's run from the top front valve cover to the bottom rear with the catch can in between. No pcv valve.

I believe there many be some modification to my inlet and outlet as well.
 
If you're asking me then it's run from the top front valve cover to the bottom rear with the catch can in between. No pcv valve.

I believe there many be some modification to my inlet and outlet as well.

Sorry Sduffass yes I was asking you.

I still have my PCV and I agree with the remove or keep idea way of thinking. There seems to be alot of back and forth on this. For me... I would rather keep it.

I also see some folks cap the throttle body ..keep the PCV and run everything into a catch can with a vented catch can..But how do you get a source for the PCV to work? I always thought it needed a vacuum (sorta) source to work..Does it still work trough the can and crankcase vent/filter connected to it?
 
Been looking into this lately and see mixed reviews to keep or remove the PCV. Any thoughts?

I do like Stevelee's design. Just not sure I like the self-draining feature yet.

CIMG6426.JPG

RYU, I think the self-draining features is one of the best features. It keeps the oil in the engine. What concerns/questions do you have about a self-draining tank?
 
RYU, I think the self-draining features is one of the best features. It keeps the oil in the engine. What concerns/questions do you have about a self-draining tank?
I'm not sure how big of a concern it is but i've seen some of the contents of catch cans and i'm not sure I'd want that crud going back into the oil pan. Your thoughts?
 
I'm not sure how big of a concern it is but i've seen some of the contents of catch cans and i'm not sure I'd want that crud going back into the oil pan. Your thoughts?

I was given the option of draining back to the oil pan, the 10an fitting I have could have easily had a line hooked up to it but after reading pros/cons to that I decided to keep it as a drain fitting...

Not to scare anyone or provoke them to change their set up but I thought what Ryu thought. Why would I be putting something on my car that catches the "bad stuff" from my engine for it to just be put back in the oil pan and recirculated.
 
I'm not sure how big of a concern it is but i've seen some of the contents of catch cans and i'm not sure I'd want that crud going back into the oil pan. Your thoughts?

The discharge that comes out of the valve cover is oily hot air from the engine. I don't think it's necessarily "bad stuff". It is used motor oil and was in the engine and when it came out it was relatively "fresh".
Oil that sits in the bottom of a non-self-draining container may develop the other "bad stuff" like sludge while sitting there for a long time, possibly due to oxidation of the oil or the tank wall, or settlement of the particles that are suspended in used motor oil, etc.
I incorporated into my "separator tank" a PCV filter that filters out contaminants.
I think this keeps the inside of my tank clean as the inside of the engine.
I designed my tank to allow the air to breathe through the PCV filter while allowing the oil to return instantly back to the motor.

One additional feature that my tank serves is that it recirculates the air that comes out of the valve covers by supplying it to the oil pump for the turbos. This allows the oil pump to run with out pulling a strong air vacuum because the tank supplies air from the valve cover. That air comes mostly from the turbos' accumulator oil tank.

Other turbo oil accumulator tanks may either have;
1.) no air vent- which is desirable to reduce the strain on the oil pump caused by the pump wanting to pump more volume of oil than actually runs through the turbo bearings, or
2.) an air vent that receives unfiltered air from the atmosphere.

My system recirculates not only engine's oil, but also the air that is inside the engine. It's a closed loop system with a PCV breather filter which allows any extra gasses (i.e. blow-by) to escape.

CIMG6413.JPG


The inlets for my tank do not discharge to the top of the tank. From the outside they look like they would. They actually discharge to the bottom where the oil can drain directly back to the oil pan. Any air vapors that are not recirculated into the engine need to travel upward through 3 sets of baffles that are designed to keep the oil in the bottom chamber. There are 2 baffled chambers directly above the bottom chamber and one filter chamber at the top off to one side.

Here's a photo of the bottom chamber of my tank that I took while I was building it.

CIMG6241.JPG


As you can see from the photos, there's a lot more to this "breather tank" than you can see from the outside.
I think of it as more of a "Multi-purpose oil/air separator and oil and air recirculation tank with a PCV breather feature".
 
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The biggest problem with the drain back feature is that you are now introducing moisture into a closed (sealed) system. As moisture invades the system via the catch can filter, oil viscosity changes. In my last turbo build (97 GSR with a huge 70 trim turbo) the valve cover had 2 2" holes drilled into the valve cover to releave the crankcase pressure into a large catch can. I did notice that the tubes going from the head to the catch can were milky due to the moisture in the air mixing with the oil.
$0.02
Jay
 
The biggest problem with the drain back feature is that you are now introducing moisture into a closed (sealed) system. As moisture invades the system via the catch can filter, oil viscosity changes. In my last turbo build (97 GSR with a huge 70 trim turbo) the valve cover had 2 2" holes drilled into the valve cover to releave the crankcase pressure into a large catch can. I did notice that the tubes going from the head to the catch can were milky due to the moisture in the air mixing with the oil.
$0.02
Jay

Most breather systems have a simple (thin) breather filter that is much like a piece of thin fabric that is supposed to trap the oil in the vapors coming from the engine and contaminants that might be going the opposite direction toward the engine.
I used a real crankcase air filter element that is about 1 inch thick. I think it is effective in minimizing the small pulses of air from going completely through the filter element and into the engine, unlike a thin cloth type filter element.

Here's a pic of the filter element I used.

CIMG6184.JPG
 
Ok in fully discussing this with my engine guru buddies, here is what we were able to come up with.

Background: In a typical engine, there is often a oily vapor that comes from the engine block. This vapor is oil blow by from tolerances such as the piston and cylinder interface. Since a typical combustion process is high in pressure and there isn't a perfect seal between the piston and cylinder wall, some air (with oil vapors and other combustion vapors) will leak around piston seals and into the engine block. All of this oily vapor is routed to a tube, and for emission purposes put back into your intake manifold where it can be reintroduced into the engine cylinders and used/burned off.

CatchCanNA.jpg


N/A and Boosted: In a N/A engine the intake manifold is normally under negative pressure as the pistons down stroke to "vacuum" intake air in the cylinder. The engine block is under positive pressure and will push the oily vapor blow-by into the vacuum created in the intake manifold. HOWEVER, in a boosted engine the intake manifold is under positive pressure (not negative). Also the combustion process is intensified, so this results in two things:

1) More blow-by around the pistons, increasing the amount of oily vapor being pushed into the block.
2) The intake manifold is now under positive pressure. Therefore the intake manifold check valve (PCV) prevents the positive intake manifold pressure coming from the super/turbocharger from pushing air/pressure back into the engine block.

As a result of these two items an oil catch can essentially becomes highly recommended, if not mandatory.

Setups: There are multiple setups for setting up a catch can. The most common is to route the block exhaust and intake manifold to a catch can with a vent. The SOS catch can, stevenlee's, EAC's catch can are all set up this way. Under boost, since the manifold is under positive pressure and the block is under positive pressure, AND the catch can is open to ambient, the flow of air will always go to the direction of the catch can. This will allow the catch can to catch all vapors off of the engine block. While not on boost, the vacuum will suck a tiny bit of air through the catch can while the block pressure will push the vapor exhaust to the catch can. Note, since the engine block vapor is NOT being returned back into the intake manifold, this car no longer technically passes emissions since the oily vapors are now open to the ambient.

CatchCanBoosted.jpg


My set up is different. My catch can is "Tee'd" off of the line instead of being inline. (See picture)

CatchCanMe.jpg


To keep the PCV or to not keep the PCV? That is the question. This is pretty simple once you understand how the oil catch can works and what kind of set up you have. If you have a catch can that is inline then it really doesn't matter if you have a PCV or not. The PCV is basically there to keep intake manifold air from pushing back on the oily block exhaust. Since the intake manifold air is now routed to an oil catch can and not the block, then it really doesn't matter since it cannot push back on the block anymore. The only reasoning I could possibly think of for not removing the PCV is that under positive boost, it would leak some boosted air out the catch can. But the pressure loss would be so minimal that it really wouldn't matter one way or another.

Now in my catch can setup, I would have to keep my PCV in. Otherwise, the oily block exhaust would flow right past my catch can and into my intake manifold OR the boosted intake manifold would blow past my catch can in the other direction, blowing into the block and prevent the oil blow-by to be relieved. By keeping the check valve in place the positive intake manifold pressure will keep the check valve closed, essentially dead ending that path. Therefore the oily engine exhaust has nowhere to go but into the catch can.

Route catch can oil back to pan?: Some people will say that the oil vapor leaving the exhaust will have products of combustion, water vapor and other contaminates in it and it will all be caught by the catch can. Others will say that being open to the ambient it will expose oil in the catch can to water vapor and the ability to condense water out as it cools in the catch can. All of these statements are somewhat true and if you've ever seen what's in the catch can, it is a pretty nasty frothy mess of watered down oil with god-knows-what else is in it. So does that mean you should absolutely not return this back to the oil pan? Not necessarily. What is caught in the catch can is what the engine would see normally anyway. And in a N/A engine, this is already returned right back into the intake manifold. While it's true there might be some water vapor introduced through the catch can due to condensing, it's not any more amount than the engine would typically see under normal operation. So ultimately, if you don't want to deal with the hassle of having to constantly empty an oil catch can, then the general consensus among my group of people seem to think it is ok. There are a number of installation where this is done with no long term affects that I know of. Although, however, if you don't want to take any chances and any risks of introducing any water and other nasties back into your system, then take the safe route and do not route the oil back into the pan. It's a peace of mind vs. convenience trade-off decision that you'll need to make.
 
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