• Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.

Catch can recirculated to intake on LoveFab turbo kit

Joined
20 January 2008
Messages
705
Location
France
Following the installation of my LoveFab turbo, I've had constant issues with oil fumes coming out of my catch tank.
The catch tank I bought is pretty basic with two inputs for the tubes coming out of the camshaft covers and a small filter on the top to allow the system to breathe.
In normal driving there is no major issue except a slight oiling of the filter but as soon as you go full power on a fast track, oil gets deposited everywhere around the filter...
Luckily D.Dozier gave me a hint to recirculate the oil fumes back into the engine air intake by taking advantage of the low pressure created right after the air filter.
The thread where it's explained is here:
http://www.nsxprime.com/forum/showthread.php/154972-Oil-catch-can/page4
The pictures will show how I did it.
Next week, I will get it back on the car for further testing.
Ideally I will need a better catch can that really allows a separation of the oil contained in the fumes.
I have no doubt it will work fine as the guy who did the soldering for me, owns an Alpine Renault "Le Mans" that uses exactly the same principle right out of the factory.
Stange that our good turbo kit suppliers didn't think about this in the first place...
Thanks D.Dozier!

DSCF5818_zps0847156d.jpg


DSCF5819_zps5613fad3.jpg
 
Last edited:
OMG im in the same boat!!! My catch can has a small filter on top that vents into the engine compartment making my cabin smell like oil/race car! im thinking about recirculating the catch can also!

Following the installation of my LoveFab turbo, I've had constant issues with oil fumes coming out of my catch tank.
The catch tank I bought is pretty basic with two inputs for the tubes coming out of the camshaft covers and a small filter on the top to allow the system to breathe.
In normal driving there is no major issue except a slight oiling of the filter but as soon as you go full power on a fast track, oil gets deposited everywhere around the filter...
Luckily D.Dozier gave me a hint to recirculate the oil fumes back into the engine air intake by taking advantage of the low pressure created right after the air filter.
I lost the thread where he explained how to do it but here are some pictures of the outcome.
Next week, I will get it back on the car for further testing.
Ideally I will need a better catch can that really allows a separation of the oil contained in the fumes.
I have no doubt it will work fine as the guy who did the soldering for me, owns an Alpine Renault "Le Mans" that uses exactly the same principle right out of the factory.
Stange that our good turbo kit suppliers didn't think about this in the first place...
Thanks D.Dozier!

DSCF5818_zps0847156d.jpg


DSCF5819_zps5613fad3.jpg
 
We get a little oil smell from the valve cover breather setup on Cody's old 'shop' car occasionally, but with the engine being new I expect it'll subside once the piston rings are properly broken in.

<a href="https://picasaweb.google.com/lh/photo/rJE2T8fI0SCEux4i-3NhSXtucMEmwfu3IXm8fcHvlTk?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-VxEKZrJuKhM/U86QMSnC0sI/AAAAAAAAAGs/zjKYi61GzCE/s800/IMG_1231.jpg" height="480" width="640" /></a>

Brian
 
We get a little oil smell from the valve cover breather setup on Cody's old 'shop' car occasionally, but with the engine being new I expect it'll subside once the piston rings are properly broken in.

<a href="https://picasaweb.google.com/lh/photo/rJE2T8fI0SCEux4i-3NhSXtucMEmwfu3IXm8fcHvlTk?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/-VxEKZrJuKhM/U86QMSnC0sI/AAAAAAAAAGs/zjKYi61GzCE/s800/IMG_1231.jpg" height="480" width="640" /></a>

Brian
Wait until you get to full power for more than 10 seconds...
 
Wait until you get to full power for more than 10 seconds...

I can't wait, but I must since he's going to give it a fresh tune tomorrow.

Full power for more than 10 seconds eats up a lot of road...... ;^D

That breather drains back into the oil pan FWIW.

Brian
 
I improved my set-up by deleting the original catch can that caught almost no oil and replacing it with a Moroso "Air/Oil separator".
The issue was that oil mist would come out of the blow-off valve during track day meetings.
The Moroso separator is basically a bottle filled with some wire mesh.
I'm not sure it's going to make that big a difference?
Mounting the device was pretty easy except that the separator comes with no instruction whatsoever...
For instance by how much can one tighten the plumbing like tubes?
The most infuriating is that the hex bolt that secures the bottle has a very odd dimension?
None of my allen keys whether metric or US fits?
In any case here's a picture.

DSCF6797_zpsxajtupve.jpg
 
The allen wrench that secures the separator is 3/16 inch.

The fittings for the air/oil lines are national pipe thread (NPT) with a taper. You need to use a thread sealant on them and make them moderately tight. Not too tight where you split the aluminum body, but tight when they are positioned the way you want them. The combination of the taper threads and the pipe sealant makes for a tight fitting.

If you have that much of a problem with blowby, then I would not want it to go through my intake - separator or not. Why take a chance with detonation? Also, is it the stock engine? Maybe time for a rebuild.

Dave
 
The allen wrench that secures the separator is 3/16 inch.

The fittings for the air/oil lines are national pipe thread (NPT) with a taper. You need to use a thread sealant on them and make them moderately tight. Not too tight where you split the aluminum body, but tight when they are positioned the way you want them. The combination of the taper threads and the pipe sealant makes for a tight fitting.

If you have that much of a problem with blowby, then I would not want it to go through my intake - separator or not. Why take a chance with detonation? Also, is it the stock engine? Maybe time for a rebuild.

Dave

Many thanks, I'll try to find a 3/16" allen wrench.
The engine internals are 100% stock and the oil consumption is almost nil.
The car has done approximately 90000 km ( 60000 miles) so I hope it's still OK?
Part of the problem might come from the fact that my setup builds more vacuum the faster the engine spins as opposed to the OEM setup where the highest vacuum comes when the throttle is closed and the blowby is minimum?
I should maybe try to fix a bleed system to limit the vacuum at a certain level?
Any idea on how to do this?
 
Last edited:
I have no doubt it will work fine as the guy who did the soldering for me, owns an Alpine Renault "Le Mans" that uses exactly the same principle right out of the factory.
Stange that our good turbo kit suppliers didn't think about this in the first place...
Thanks D.Dozier!

The reason why aftermarkets don't include this feature is because it is detrimental to performance unless you are running piston rings that flutter excessively.

An OEM primarily includes a closed crankcase ventilation system that does not vent to atmosphere because of environmental regulations. Most aftermarket setups vent oil vapors to the environment which is good for the engine but bad for the environment.

Closed Crankcase Ventilation Pros (like OEM and what you have done):
Helps keep the air we breathe clean
Helps engine oil by removing water vapor and combustion byproducts
In some cases may aid piston ring seal which leads to better performance. For a basically stock OEM engine, this is negligible.

Closed Crankcase Ventilation Cons:
Circulates oil, water vapor, and combustion byproducts to your engine intake
Effective air/oil separators are expensive


Open Crankcase Pros:
Doesn't introduce ANY contaminants to your engine intake
Cheap

Open Crankcase Cons:
Oil smell from car
Bad for our environment
Doesn't clean the engine oil as well
Unless you have very low tension piston rings or those that flutter excessively, you won't get any benefit from drawing a small vacuum


Now, another setup is to use an exhaust-driven scavenging system where you stick that Bernoulli-style obstruction you have on your intake pipe into an exhaust pipe. It now sucks the crankcase vapors into the exhaust. Ideally, you'd want to stick that downstream of any cats and absorption-type mufflers. You'll need a vacuum relief valve with a filter on one of the valve covers as a source of fresh air into the crankcase for everything to circulate. This setup really gives you the better option than the intake-style. No air/oil separator is needed and you are helping keep your oil clean, but you are still effectively venting oily vapors to the atmosphere.

Dave

- - - Updated - - -

I should maybe try to fix a bleed system to limit the vacuum at a certain level?
Any idea on how to do this?

Excessive crankcase POSITIVE pressures from blowby are a problem because they can lead to crankshaft main seals blowing out or oil pan/valve covers leaking. Dealing with a crankcase vacuum is a much better situation than dealing with the opposite. Besides, with the differential pressure you'd generate from that intake obstruction, I don't think you'll have any issues. Therefore, no need for a relief valve unless you want a small source of filtered outside air to enter and circulate.

Dave

- - - Updated - - -

That breather drains back into the oil pan FWIW.

That's a big can. Have you ever blocked off the drain to see what you collect in it?
 
Dealing with a crankcase vacuum is a much better situation than dealing with the opposite. Besides said:
Dave many thanks for the feedback.
Would you know how the maximum vacuum levels compare between the OEM setup and a bernouilli tube intake setup (on a turbocharged car)?
If I decided to try a relief valve do you have any recommendation?

John

- - - Updated - - -

The reason why aftermarkets don't include this feature is because it is detrimental to performance unless you are running piston rings that flutter excessively.

An OEM primarily includes a closed crankcase ventilation system that does not vent to atmosphere because of environmental regulations. Most aftermarket setups vent oil vapors to the environment which is good for the engine but bad for the environment.

Closed Crankcase Ventilation Pros (like OEM and what you have done):
Helps keep the air we breathe clean
Helps engine oil by removing water vapor and combustion byproducts
In some cases may aid piston ring seal which leads to better performance. For a basically stock OEM engine, this is negligible.

Closed Crankcase Ventilation Cons:
Circulates oil, water vapor, and combustion byproducts to your engine intake
Effective air/oil separators are expensive


Open Crankcase Pros:
Doesn't introduce ANY contaminants to your engine intake
Cheap

Open Crankcase Cons:
Oil smell from car
Bad for our environment
Doesn't clean the engine oil as well
Unless you have very low tension piston rings or those that flutter excessively, you won't get any benefit from drawing a small vacuum


Now, another setup is to use an exhaust-driven scavenging system where you stick that Bernoulli-style obstruction you have on your intake pipe into an exhaust pipe. It now sucks the crankcase vapors into the exhaust. Ideally, you'd want to stick that downstream of any cats and absorption-type mufflers. You'll need a vacuum relief valve with a filter on one of the valve covers as a source of fresh air into the crankcase for everything to circulate. This setup really gives you the better option than the intake-style. No air/oil separator is needed and you are helping keep your oil clean, but you are still effectively venting oily vapors to the atmosphere.

Dave

- - - Updated - - -



Excessive crankcase POSITIVE pressures from blowby are a problem because they can lead to crankshaft main seals blowing out or oil pan/valve covers leaking. Dealing with a crankcase vacuum is a much better situation than dealing with the opposite. Besides, with the differential pressure you'd generate from that intake obstruction, I don't think you'll have any issues. Therefore, no need for a relief valve unless you want a small source of filtered outside air to enter and circulate.

Dave

- - - Updated - - -



That's a big can. Have you ever blocked off the drain to see what you collect in it?

Dave many thanks for the feedback.
Would you know how the maximum vacuum levels compare between the OEM setup and a bernouilli tube intake setup (on a turbocharged car)?
If I decided to try a relief valve do you have any recommendation?

John
 
Dave asked;

That's a big can. Have you ever blocked off the drain to see what you collect in it?


I've never done that, but expect that there would be very little if I did.

Brian
 
Following a disappointing result after my track day test of the Moroso AOS, I decided to modify the setup to further eliminate any oil vapor coming out of the BOV.
As a reminder, I had routed both valve cover outlets into the Moroso AOS, the outlet of which going into a "bernouilli" type tube before the turbo to create the vacuum.
This time, I connected only the front valve cover outlet to the Moroso AOS while the rear valve cover gets fresh air into the engine through a basic catch can equipped with a small air filter.
This scheme reproduces the OEM setup with air flowing through the engine from the rear valve cover through to the front one.
The vacuum source remains the turbo inlet.
I'm not convinced this will work any better as the speed of the air flow through the Moroso AOS should be greater giving the oil less chance to coalesce before getting to the turbo's intake?
On the other hand the vacuum created inside the engine should be lower thus sucking less oil through the Moroso AOS?
The reason I put a catch can on the rear valve cover is in case some positive pressure would arise sending oil in the wrong direction.
Here are some pictures of the setup:

DSCF7019_zpsiqfaiakm.jpg


DSCF7018_zpslfaohz7s.jpg
 
Last edited:
Do you have the old style rear valve cover like I do?

I am thinking the only way to do this would be to have 2 AOS cans, one each bank.

- - - Updated - - -

I also put back the front pcv but still tinkering. No news to report yet...
 
Last edited:
I am thinking the only way to do this would be to have 2 AOS cans on each bank.
One on each bank (two total) or two on each bank (four total)? Isn't the setup described above one on each bank? I'm struggling to figure out why one would want more.
 
One on each bank (two total) or two on each bank (four total)? Isn't the setup described above one on each bank? I'm struggling to figure out why one would want more.

Typo...One on each bank. I suspect the rear bank doesn't like to see vacuum which is why the oem rear bank is routed before the TB. don't see why it matters but I'll try it anyway. still playing with it though. T'ing booth into one AOS might still work because I put the pcv back on in the front bank. Hope to report back on my thread in a few weeks.
 
Last edited:
The OE setup provides for the pressure differential across the throttle body to drive flow through the engine from the rear head to the front head (reversed in the NA2). If you T the heads, there is nothing driving flow other than blowby (primarily under high-load conditions).

The setup with two AOS emulates the OE setup by allowing fresh filtered air in one bank (running backwards through the vented AOS) to be drawn out the other bank by the post-TB vacuum (through the nonvented AOS). Under high-load, blowby causes positive pressure at both heads and drives flow through both AOS. I think [MENTION=12356]Mac Attack[/MENTION] has it correct in that regard. The fresh air can come in through the vent of the AOS or can come from a pre-TB tap. The difference is only where the blowby gases end up.
 
The OE setup provides for the pressure differential across the throttle body to drive flow through the engine from the rear head to the front head (reversed in the NA2). If you T the heads, there is nothing driving flow other than blowby (primarily under high-load conditions).

The setup with two AOS emulates the OE setup by allowing fresh filtered air in one bank (running backwards through the vented AOS) to be drawn out the other bank by the post-TB vacuum (through the nonvented AOS). Under high-load, blowby causes positive pressure at both heads and drives flow through both AOS. I think @Mac Attack has it correct in that regard. The fresh air can come in through the vent of the AOS or can come from a pre-TB tap. The difference is only where the blowby gases end up.
Thanks for that explanation. I would have never thought that's how it worked.

How important do you think the flow thru the engine is? Honda thought well enough to incorporate it surely but it wasn't designed for boost.

I'm thinking of buying another catch can (sigh).

In a 1 AOS setup, even if I "T" it off and omit the flow-thru circulation I would need a PCV for the rear bank. Effectively, for now, I can only route my catch can to one bank. Some here on prime routed it to the rear. @michaelbrat any reason why you chose the rear only? I remember reading, due to the valve cover design, the rear was more prone to spew oil but i'd assume blow-by pressures should be relatively the same on both banks.
 
Last edited:
Flow through the engine serves the purpose of cleaning the oil. For that reason I consider it important. And if you use the dual AOS like Mac Attack suggests, then I see no downside.

I don't believe you would want two PCV valves, as that would prevent flow from entering the engine.
 
Do you have the old style rear valve cover like I do?

I am thinking the only way to do this would be to have 2 AOS cans, one each bank.

- - - Updated - - -

I also put back the front pcv but still tinkering. No news to report yet...

I don't know which valve cover I have?
How can one recognize the one from the other?

- - - Updated - - -

The OE setup provides for the pressure differential across the throttle body to drive flow through the engine from the rear head to the front head (reversed in the NA2). If you T the heads, there is nothing driving flow other than blowby (primarily under high-load conditions).

The setup with two AOS emulates the OE setup by allowing fresh filtered air in one bank (running backwards through the vented AOS) to be drawn out the other bank by the post-TB vacuum (through the nonvented AOS). Under high-load, blowby causes positive pressure at both heads and drives flow through both AOS. I think [MENTION=12356]Mac Attack[/MENTION] has it correct in that regard. The fresh air can come in through the vent of the AOS or can come from a pre-TB tap. The difference is only where the blowby gases end up.

I only hope that the vacuum created by the bernouilli tube connected to the turbo inlet is high enough to negate any positive pressure created by the blow-by thus avoiding any oil flowing into the "rear" catch can.
Let's not forget that in this FI system the vacuum increases as the revs increase just like the blowby does.
In the oem setup it's the reverse: more revs more blowby but less vacuum.
 
Last edited:
I bought an SOS oil catch tank kit.

But i removed it and now have a small filter sitting on each bank that vents straight to the atmosphere.

This method is popular in the tuning world but don't see it much on the Nsx.

I've not really noticed much smell or oil build up on my engine cover. Simple solution, less clutter in the bay and allot lighter ;).
 
Last edited:
I don't know which valve cover I have?
How can one recognize the one from the other?
I read it on http://dalmotorsports.com/ but my work filters will not allow me to browse the mirror on waybackmachine

- - - Updated - - -

I bought an SOS oil catch tank kit.

But i removed it and now have a small filter sitting on each bank that vents straight to the atmosphere.

This method is popular in the tuning world but don't see it much on the Nsx.

I've not really noticed much smell or oil build up on my engine cover. Simple solution, less clutter in the bay and allot lighter ;).
That method would yield a messy messy engine bay for me especially a high G road course :(
 
I went for a short ride today to test my latest catch can setup.
As a reminder, fresh air is allowed to enter the rear cylinder bank through a basic AOS fitted with a small breather filter and then pulled out the front cylinder bank through a Moroso AOS with a bernouilli tube acting as the vacuum source ahead of the turbo.
Well, disapointment again as the surroundings of the BOV where covered with a thin layer of oil...
The only good news is that there was no oil coming out of the breather filter meaning that there is enough vacuum created to pull all the oil mist through the front camshaft cover.
Before switching to the exhaust as a source of vacuum, I'll try to disconnect the vacuum source from the intake and see what happens?
Am I the only one to suffer this issue???
 
But i removed it and now have a small filter sitting on each bank that vents straight to the atmosphere.

This method is popular in the tuning world but don't see it much on the Nsx.

That works to vent the crankcase for the purpose of preventing pressure build up. It does nothing to force air flow through the crankcase to assist in the removal of moisture and other contaminants that build up in the oil. That may or may not be an issue depending on your climate and how many cold - hot start cycles the engine goes through between oil changes.

Also, depending on local track regulations, I seem to recall that venting to atmosphere, even with filters, may not be acceptable. Track owners and racing regulating bodies are not keen about having a failed engine puking its crankcase contents out on to the track surface (drivers in following cars even less keen about that). I think the oil catch can is primarily a safety device.
 
Before going any further, I opened the Moroso AOS to investigate their design.
In fact it's far better than I thought with a clear separation between the input and the output as you can see from the pictures.
The weak point might come from the fact that the speed of the air flow doesn't drastically decrease going through the AOS?
If I had to build one I would probably let the incoming flow go into a large chamber with multiple vertical plates arranged in a maze a bit like an intercooler design to force the oil to coalesce on the very large surfaces.

DSCF7066_zpsipakl8le.jpg


DSCF7065_zpso2px42w0.jpg
 
The main issue I see with this type of install, is the amount of volume (hose diameter) is so small, (OEM spec), its insufficient at venting the pressure at high boost levels / high rpm for extended periods of time.

At minimum, the line diameter should be 3/4" (#10 AN)
 
Back
Top