Catch Can / Breather Filter Install (Lots of Pics)
12-08-2008, 01:30 PM
#43
I never said it didn't help. It's the only source of venting under boost if your pcv valve is installed so of course it works. But to vent it to the atmosphere with a breather filter or have it routed back into the intake makes no difference to venting the crankcase.
12-08-2008, 01:38 PM
#44
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Spoilsofwar fixed the TN problem..
here you go.. Smoke coming from exhaust...
read that whole thread
here you go.. Smoke coming from exhaust...
read that whole thread
12-08-2008, 02:36 PM
#45
It's the only source if your PCV valve is installed AND routed directly to the plenum. As has been mentioned in several threads, you can tie the PCV output via a catch can to the driver's side intake via a T and a check valve. Then it can make a bigger difference.
The difference is that under boost, by having a breather in place, you can facilitate crankcase ventilation. If the PCV is blocked off (due to just being tied to the plenum) during boost and the driver's side breather is tied to the intake, I have found that this setup sucks more oil out of the crankcase than if you have a portal for fresh air to ensure cc pressure does not exceed atm.
The better solution is to have fresh air sweep through the crankcase and pull out just the fumes. If the stock PCV valve is incapable of flowing enough air during boost, then the breather on the driver's side serves as an overflow escape portal.
Bottomline, I think we agree that the way doug has it now (modifying only the driver's side) won't hurt and will serve to prevent oil from being sucked into the intake.
Last edited by rcdash; 12-08-2008 at 02:38 PM.
12-08-2008, 04:36 PM
#49
Bottomline, I think we agree that the way doug has it now (modifying only the driver's side) won't hurt and will serve to prevent oil from being sucked into the intake.
It seems like only a few people here understand how this system works even though it's been rehashed in about 4 threads and I have written a desription in my blog which I doubt anyone read.
In order to partake in any meaningful discussion everyone involved needs to know how the OEM system works.
Everyone is buying meaningless check valves and throwing everything they can think of at the problem and getting no where when there is already a solution which I also wrote about in my blog and Sharif has posted about and is easilly and cheaply implemented.
Last edited by JETPILOT; 12-08-2008 at 04:39 PM.
12-08-2008, 04:57 PM
#50
For those who didn't click on JET's blog link, I copied it here so you have no excuse!
LOL
I highlighted how the OEM system works, since that seems to be where the breakdown in understanding is.
Thanks JET. I intend to consult Intense about this issue before my build is completed.
LOL I highlighted how the OEM system works, since that seems to be where the breakdown in understanding is.
The 350Z crankcase ventilation was designed with a constant source of vacuum in mind from the intake manifold through the PCV fitting located in the passengers side valve cover. Under normal conditions the PCV is under constant vacuum. The more power you are making out of boost the bigger the vacuum and the more air is removed from the crankcase through the PCV valve. Without the PCV valve when wide open throttle the crankcase would pressurize with air/fuel mixture from the combustion chamber blowing by the rings and pressurizing the crankcase.
Under light to moderate throttle when out of boost the crankcase is not pressurizing because the PCV valve is still open and the crankcase is still being ventilated. To replenish the air exiting the PCV valve the drivers side valve cover vent allows air to enter and crossover into the pax side valve cover and through the oil drain holes enter the crankcase where it is sucked out again through the PCV valve into the plenum. The PCV valve is always open to some degree except when there is a backfire which would close the PCV valve since the airflow would be opposite to what is normal.
Now that we know how the PCV system is designed to work let’s look at what happens when you hook up some forced induction. When you pressurize the intake plenum by means of turbocharger/supercharger you are forcing the PCV valve closed removing the crankcases source of vacuum ventilating it. The increased cylinder pressure blows by the piston rings into the crankcase and since the PCV valve is closed has only one direction to take. The pressurized crankcase pressurizes the pax side valve cover, travels through the crossover hose into the drivers side valve cover which is already pressurized and it all tries to leave through the tiny opening in the pax side valve cover breather into the turbo air intake. To make the situation worse the pressure in the crankcase also pressurizes the turbo oil return lines casuing the turbo seals to leak oil into your compressor housing /intercooler and into your turbine housing/exhaust. If your intercooler is full of oil this is the cause.
The system was never designed to flow in that reverse direction. The drivers side breather was only designed to flow into the valve cover across the connecting hose into the pax side valve cover. The small breather hole in the drivers side valve cover is only big enough to deal with ventilating the volume of crankcase gasses from a 300hp NA motor. The system cannot operate as it was designed when we pressurize the manifold, increase blow-by, and remove the vacuum source. It is grossly inadequate.
I have a few ideas in mind and will be modifying the PCV system to vent to the atmosphere. The simplest mofification to start with is to diable the OEM PCV system. To do this you need to put a vacuum cap over the plenum PCV hose fitting. Drill out the PCV valve and remove the white valve. Run a hose to a catch can and vent the catch can to the atmosphere. Stay tuned over the next week or so and I’ll share with you what I find. If this doesn't work to relieve the crankcase pressure I have other ideas. Others have reported something simlar to this fix working. My next track day @ Sebring is 12/14. Stay tuned for results.
Under light to moderate throttle when out of boost the crankcase is not pressurizing because the PCV valve is still open and the crankcase is still being ventilated. To replenish the air exiting the PCV valve the drivers side valve cover vent allows air to enter and crossover into the pax side valve cover and through the oil drain holes enter the crankcase where it is sucked out again through the PCV valve into the plenum. The PCV valve is always open to some degree except when there is a backfire which would close the PCV valve since the airflow would be opposite to what is normal.
Now that we know how the PCV system is designed to work let’s look at what happens when you hook up some forced induction. When you pressurize the intake plenum by means of turbocharger/supercharger you are forcing the PCV valve closed removing the crankcases source of vacuum ventilating it. The increased cylinder pressure blows by the piston rings into the crankcase and since the PCV valve is closed has only one direction to take. The pressurized crankcase pressurizes the pax side valve cover, travels through the crossover hose into the drivers side valve cover which is already pressurized and it all tries to leave through the tiny opening in the pax side valve cover breather into the turbo air intake. To make the situation worse the pressure in the crankcase also pressurizes the turbo oil return lines casuing the turbo seals to leak oil into your compressor housing /intercooler and into your turbine housing/exhaust. If your intercooler is full of oil this is the cause.
The system was never designed to flow in that reverse direction. The drivers side breather was only designed to flow into the valve cover across the connecting hose into the pax side valve cover. The small breather hole in the drivers side valve cover is only big enough to deal with ventilating the volume of crankcase gasses from a 300hp NA motor. The system cannot operate as it was designed when we pressurize the manifold, increase blow-by, and remove the vacuum source. It is grossly inadequate.
I have a few ideas in mind and will be modifying the PCV system to vent to the atmosphere. The simplest mofification to start with is to diable the OEM PCV system. To do this you need to put a vacuum cap over the plenum PCV hose fitting. Drill out the PCV valve and remove the white valve. Run a hose to a catch can and vent the catch can to the atmosphere. Stay tuned over the next week or so and I’ll share with you what I find. If this doesn't work to relieve the crankcase pressure I have other ideas. Others have reported something simlar to this fix working. My next track day @ Sebring is 12/14. Stay tuned for results.
12-08-2008, 05:52 PM
#53
To give credit where credit is due this is Sharif's idea. He tried it and says it worked at the track. I have no reason to think it won't. As per my understanding of how the cc evac works this mod certainly makes sense.
For those in emissions states it would be ver yeasy to re-install a functioning PCV valve and reconnect it to the manifold to have a functioning PCV system again for the yearly sticker test.
Three thumbs up for this mod.
For those in emissions states it would be ver yeasy to re-install a functioning PCV valve and reconnect it to the manifold to have a functioning PCV system again for the yearly sticker test.
Three thumbs up for this mod.
12-08-2008, 06:43 PM
#54
Actually I don't agree. Oil does not come out of the drivers side valve cover breather. I checked my hose and I have none. The drivers side valve cover breather is only meant to have air flow IN per OEM design. But under boost we are using it as our ONLY source of cc evac.
It seems like only a few people here understand how this system works even though it's been rehashed in about 4 threads and I have written a desription in my blog which I doubt anyone read.
In order to partake in any meaningful discussion everyone involved needs to know how the OEM system works.
Everyone is buying meaningless check valves and throwing everything they can think of at the problem and getting no where when there is already a solution which I also wrote about in my blog and Sharif has posted about and is easilly and cheaply implemented.
It seems like only a few people here understand how this system works even though it's been rehashed in about 4 threads and I have written a desription in my blog which I doubt anyone read.
In order to partake in any meaningful discussion everyone involved needs to know how the OEM system works.
Everyone is buying meaningless check valves and throwing everything they can think of at the problem and getting no where when there is already a solution which I also wrote about in my blog and Sharif has posted about and is easilly and cheaply implemented.
I also believe that check valves are required for an optimal setup. If there's any part that you don't understand, I'd be happy to try to explain it. I've read your blog and its mostly correct except this part doesn't make sense:
The pressurized crankcase pressurizes the pax side valve cover, travels through the crossover hose into the drivers side valve cover which is already pressurized and it all tries to leave through the tiny opening in the pax side valve cover breather into the turbo air intake
Last edited by rcdash; 12-08-2008 at 07:05 PM.
12-08-2008, 07:06 PM
#56
I don't know why I said that.. but your right. But that's neither here nor there. The issue here is that you can't evacuate both valve covers through the breather in the divers side valve cover. It can't flow enough voume. I wasn't reffering to you when I made those comments about not understanding the system. The important thing is to open up a vent in the pax side valve cover to make sure it vents under boost unlike the OEM PCV which doesn't.
12-08-2008, 07:09 PM
#57
I don't know why I said that.. but your right. But that's neither here nor there. The issue here is that you can't evacuate both valve covers through the breather in the divers side valve cover. It can't flow enough voume. I wasn't reffering to you when I made those comments about not understanding the system. The important thing is to open up a vent in the pax side valve cover to make sure it vents under boost unlike the OEM PCV which doesn't.
12-09-2008, 05:16 AM
#60
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Do not try to drill from the top, drill from the bottom and remove the valve and spring that way.