Jump to content
SAU Community

Recommended Posts

G'day guys,

Been doing a fair bit of reading on SAU and other places regarding blow-by, catch-cans and the good ol' PCV valve.

For now, let's assume we don't want to vent to atmosphere - i know we probably do, but for this argument, let's pretend we don't :)

It seems there's two trains of thought regarding blocking the PCV. Some say you need to leave it intact if you're not venting to atmo, others say it's best to block it.

I'm trying to get my head around which is actually better, and why.

The way I understand it, in 'stock' configuration, the PCV allows the engine to breathe into the intake manifold while under vacuum, and closes under boost, when it can breathe via the exhaust side hose into the pre-turbo intake pipe.

If we were to just block the PCV, and change nothing else, wouldn't it just mean that all of the breathing would happen via the turbo inlet pipe? Aside from the large amounts of oil that would be pushed into the intake, are there any other issues with this?

If we then put a catch can with a decent oil/air separator setup in between the rocker cover and the intake pipe, wouldn't this allow the engine to breathe as required, without pushing any oil directly into the intake manifold and reducing the octane rating?

I figure I must be missing something here - mainly because of this: Nissan put a PCV valve in there for a reason - it must be required for something I'm overlooking! :rofl:

Link to comment
https://www.sau.com.au/forums/topic/345545-oil-catch-canpcv-setups/
Share on other sites

The way i see it leave the pcv alone and remove and block the intake side at the turbo. This actually pulls oil out ofthe head in a way. There is alot of vacuum there.

I'm aware of how that works - but wouldn't it be better to prevent as much oil vapour from entering the intake as possible? does it actually *need* to be 'drawn out' - isn't it enough to just let it breathe 'naturally'?

I'm trying to work out what the 'reason' behind leaving the PCV setup stock and allowing it to breathe into the intake manifold is...

zyeby9.jpg

This is my setup. Yes you need to draw Crank case ventilation from your engine. Believe it or not, you actually want vacuum in your crank case to help pull the ring down on to the ring land of your piston which also helps the push the ring against the bore.

Leaving the tube from your rocker cover to your turbo helps the no end.

Following the diagram, All the red lines are contaminated with oil, all the blue lines are scrubbed from vapor by baffling and steel wool in the oil air separator.

This setup is completely sealed and legal. It never needs to be drained and has 0 maintenance.

I just leave my dipstick tune in my boot and use it when necessary.

Edited by HYPED6
  • Like 1
zyeby9.jpg

This is my setup. Yes you need to draw Crank case ventilation from your engine. Believe it or not, you actually want vacuum in your crank case to help pull the ring down on to the ring land of your piston which also helps the push the ring against the bore.

Leaving the tube from your rocker cover to your turbo helps the no end.

Following the diagram, All the red lines are contaminated with oil, all the blue lines are scrubbed from vapor by baffling and steel wool in the oil air separator.

This setup is completely sealed and legal. It never needs to be drained and has 0 maintenance.

I just leave my dipstick tune in my boot and use it when necessary.

wouldnt this setup still have the same effect if used without the pcv and line? also what do you have in the catch can to stop steel wool fibres from being sucked up?

yeah thought about that.. problem is i couldn't because of the way the catch can is designed- can't open it up

i could only stuff the stainless steel wool in through the fittings

i'm using the thicker scourer type of steel wool, not the cotton look-alike soapy pad type

Edited by chiksluvit

pcv is there because what comes out the engine breathers is no good for the environment and counts as part of total emissions and the easiest way to deal with it is to burn it (cheap skate factory. well i dont blame them really )

block the pcv . no oil shit stinkin up the intake manifold

run a decent air/oil seperator baffled catch can between the rockers and turbo intake . no oil in anything systen still sealed . engine breathes fine because there is partial vacuum between the afm and

hard to jump in after the paint-master HYPED, but here goes..

I have welded a fitting onto my turbo oil drain on the block (hot-side), as setup as follows

I haven't planned on using the PCV, any problems with this setup? i haven't used it yet, the car is due to turn over in a couple of weeks.. This thread had me thinking, under boost, could i possibly be sucking oil up the oil drain and into my catchcan?? i'm guessing the turbo inlet pipe produces a vacuum but unsure to what extent..

post-30449-1291160181_thumb.jpg

wouldnt this setup still have the same effect if used without the pcv and line? also what do you have in the catch can to stop steel wool fibres from being sucked up?

Yes, if you block the PCV valve and the return line, you would just put little filters on the top of the catch can to run atmo.

hard to jump in after the paint-master HYPED, but here goes..

I have welded a fitting onto my turbo oil drain on the block (hot-side), as setup as follows

I haven't planned on using the PCV, any problems with this setup? i haven't used it yet, the car is due to turn over in a couple of weeks.. This thread had me thinking, under boost, could i possibly be sucking oil up the oil drain and into my catchcan?? i'm guessing the turbo inlet pipe produces a vacuum but unsure to what extent..

post-30449-1291160181_thumb.jpg

I'd be worried about introducing that kind of vacuum to the turbo oil return...

It would be drawing air from the crankcase via the the turbo drain.. air that would be flowing against the oil trying to drain out of the turbo (could there be enough vacuum at high rpms to pull oil up in to the can??).. the oil is not under any pressure but neither is the oil trying to flow back from the head down the factory drains (the reason why we go to these breathing extremes).. It would also mean there is a constant vacuum (fed in part by the drain) in the can which probably wouldn't help the oil to drain.

I dunno, I just wouldn't screw with it is all :)

Edited by bubba

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...