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Discussion Starter #1 (Edited)
This thread is primarily directed toward people with FI, and even more specifically for those with built motors and set ups with Garret turbos (APS, JWT, etc...)
I have been running my built APS set up for a couple years now with pretty much no problems, but I've been noticing some oil smoke lately at WOT. I did tons of research into what could be causing this, and decided high crank case pressure was probably the likely culprit. Apparently, the Garret turbos are very sensitive to oil pressure, crank case pressure, etc, so I set out the fix the problem.
My oil catch tank set up the "normal" way was catching a good bit of oil, but I had nothing set up to allow the crank case to vent. The stock PCV is a known problem with higher boost, so I figured that should probably go. After a ton of research and annoying PMs to people smarter than I, this is what I've come up with. It allows the crankcase to vent without restriction, and also maintains vacuum pressure at idle. This allows the rings to seat properly at idle, and also keeps a steady supply of fresh air moving through the crank case.

What you need:
-Catch tank
-About 6 feet of reinforced 3/8 vacuum hose (I ordered 8ft and had a little left over)
-Brake booster check valve with 3/8 barbed ends - this is the hardest part to find. I ordered a check valve off a Nissan Pathfinder from autopartswharehouse, but I believe all the Nissan check valves are pretty much the same. Finding one with 3/8 barbs is the trick, I could not find one locally.
-3/8 Tee
-Mini-breather to fit on PCV
-2 connections to join 5/8 hose with 3/8 hose (I couldn't find these at the auto parts store, so I went to home depot and made some)

How to do it:

1. Remove front strut bar and plastic engine cover
2. Remove hose connecting PCV valve and lower plenum (in stock configuration)
3. Remove PCV


4. Drill it out. Remove the spring and little floating plastic piece




5. Replace now-drilled-out PCV into the valve cover and attach the breather to it


Now to the more complicated driver side.

6. Remove the charge pipe

7. LOCATE: There is a 5/8 heater hose that runs from the very back of the driver side valve cover straight to the driver side turbo intake (traced in red)


8. Find a nice place to cut it. I left about 6" of the original 5/8 hose running off the turbo intake because it was pre-bent, and made it very convenient to attach the new 3/8 vacuum hose.
9. Place your 5/8-3/8 connectors into both ends of the 5/8 hose you just cut.


10. Attach the 3/8 vacuum hose to the converter on the short hose coming off of the turbo intake. Run this new hose over to the lower plenum. Cut it your desired length and hose clamp it to the lower plenum inlet.


11. Attach 3/8 vacuum hose to the converter on the 5/8 hose running to driver side valve cover. Route this new vacuum hose straight to the catch tank and trim to desired length. At this point, all your new hoses are in place (we just have to add in a few goodies), so make sure they are trimmed just how you want them.
12. Replace charge pipe. Situate all new hoses how it suites your engine bay best.
13. Pick a spot on the vacuum line that is now running from the lower plenum to the driver turbo intake and cut it near the catch tank. Insert the Tee at this cut.


14. Run another 3/8 vacuum line from the Tee into the catch tank.

15. Pick a spot on the vacuum line running from the lower plenum (before the Tee) and cut it. Insert the check valve (this needs to be placed so that air can be drawn INTO the plenum, but NOT pushed back OUT into the catch tank).


16. At this point, everything is functional. I hose clamped everything down, which was probably completely unnecessary, but just in case!


17. Bolt everything back up and go test out your new set up!


...for those of you who are still confused (if that's possible), I drew up a little sketch for you...



Hope this has simplified everything, I would encourage anyone running high boost to check out some type of crank case ventilation set up like this...
Good luck!!!
-Willy P-
 

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Discussion Starter #3
Nice write up. I have been meaning to do one but never got around to doing it
I gave it some good pulls tonight, the car reacted great!
...I am idling leaner though, what is "too lean" for idling?
 

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Discussion Starter #5
as long as it is idling ok without stumbling it really doesn't matter, Mine has been around 16 afr and still idled ok your af sensor is probably further back than stock so reading a bit lean is not a problem.
Oh, well it is idling at about 16, so that's good news : ) It stumbles like once every 60 seconds I'd say... Having said that I don't just sit at idle for long periods of time, I only notice it at long red lights...
 

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Discussion Starter #7
even so, i would try and figure out why it has changed
Well I was suspecting that it is because the PCV is now breathing and the plenum is routed a little different, but I'm gonna go look for leaks just in case :)
 

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I sent you a pm but I was looking at your diagram a little closer and if it setup like the last picture with the red lines I would think you are getting un-metered air into the vacuum port on the plenum from the intake pipe which would cause you to run leaner.

Or maybe I am just not all the way awake yet
 

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Discussion Starter #9
I sent you a pm but I was looking at your diagram a little closer and if it setup like the last picture with the red lines I would think you are getting un-metered air into the vacuum port on the plenum from the intake pipe which would cause you to run leaner.

Or maybe I am just not all the way awake yet
Haha, that is correct... you're a smart guy even before you're awake : )
 

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Discussion Starter #10
Ok, so I noticed my a/f was lean and my boost gauge was reading less vacuum pressure. It didn't occur to me at first, but this obviously means there is more air flowing into the plenum vacuum spot with less resistance. Obviously this is because with my set up, air was flowing into the plenum through a reinforced 3.8 hose at the SMALLEST, where as in the stock set up, it is sucking air through the PCV which is restrictive and only a 1/4" hole. It kind of hit me, then, that I needed to add some resistance back into my hose that runs to the plenum.
So, I went and got some 1/4" hose and rigged some more adapters.


Even this was not nearly as restrictive as the PCV so I made a little loop of 1/4 hose (the longer the hose, the more restriction there is...)



This about did the trick. It is SLIGHTLY leaner than it was, but I think it WAS too rich. Now, my a/f is back down, my vacuum pressure is back up, and my idle seems to be pretty much perfect again...



Just tucked it away back underneath the engine cover, and everything seems to be running great!!!

...hope this helps someone....

-Willy-
 

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Hi Willy been following your catch can development ( with Kam ) and my research has come up with the same system as you have but with another check valve between the "T" and the intake. My reasoning was for the plenum to draw using vacuum at idle and low rpm and the intake to draw at higher rpm. So to avoid unmetered air and to safe guard against backfire i came up with the 2 check valves. This may explain your lower vacuum. I like your 5/8-3/8 reduction method. I'm going with a HKS S/C. Do you recall the part number for the check valve?
 

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Discussion Starter #12
Hi Willy been following your catch can development ( with Kam ) and my research has come up with the same system as you have but with another check valve between the "T" and the intake. My reasoning was for the plenum to draw using vacuum at idle and low rpm and the intake to draw at higher rpm. So to avoid unmetered air and to safe guard against backfire i came up with the 2 check valves. This may explain your lower vacuum. I like your 5/8-3/8 reduction method. I'm going with a HKS S/C. Do you recall the part number for the check valve?
Where would you put the other check valve? (note the arrow on my diagram is actually drawn backwards)
...putting a check valve between the can and the turbo in take would allow air to but sucked only into the intake and not pushed back out. This should be superfluous, though, because the turbo intake is always under vacuum and never making positive pressure that would push back into the can, and thus need to be blocked. The plenum DOES make positive pressure under boost, so it must have a check valve...
note, there is no check valve in the stock set up for this reason...
 

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Thats what we need, the intake/plenum doing the work of evacuating the crankcase of all the blow by gases at all of the rpm range. The plenum (vacuum) at low rpm and the intake at higher rpm ( as more air rushes by the opening it draws the gases through CC. So we don't want air being forced back int the CC at any time , hence my reasoning for the check valve between the CC and the intake.)
I'm hoping the CC will be efficient at this point and doing it's job not letting any oily contaminates into our intakes and IC.
 

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Discussion Starter #14
Thats what we need, the intake/plenum doing the work of evacuating the crankcase of all the blow by gases at all of the rpm range. The plenum (vacuum) at low rpm and the intake at higher rpm ( as more air rushes by the opening it draws the gases through CC. So we don't want air being forced back int the CC at any time , hence my reasoning for the check valve between the CC and the intake.)
I'm hoping the CC will be efficient at this point and doing it's job not letting any oily contaminates into our intakes and IC.
That is exactly what is happening with my set up... I have 2 more check valves sitting in my floor, but there should be no reason to put another one in... the turbo intake doesn't "boost" so to speak, it cannot force pressure back into the crankcase like the plenum can, so there's not need for a check valve on it...
I know it's confusing, I will try to draw separate diagrams for airflow under idle (plenum vacuum) and airflow under boost (turbo intake vacuum)
 

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Ah well, i guess all we can do is go with our strategy and monitor the CC and the IC. At the very least both approaches are relieving the crankcase of any piston ring blow by.
Do you have that part number handy?
 

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Discussion Starter #16

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Discussion Starter #19
Here are some more complete diagrams I drew up... I hope this clears up any confusion with the check valve(s)...



 

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Hey Willy great diagrams they are great way to visualise , i did the same. What i'l do is the same and monitor the intake hose. I'm going with a HKS S/C.
How is your CC setup running has it collected anything? Your motor is built so i imagine its running without any or much blow by.
Was the valve the right diameter for the 3/8 hose you used? Just as a side note Nissan Australia quoted me $66.00 for the check valve! Thats gouging!!!
 
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