Oil in upper/lower intake on a supercharged car....pcv?

BlueOvalStangGT · Nov 25, 2005

I pulled my upper today for the new injectors I have and there was oil across all ports. Im still running the stock pcv valve, is that why? I heard some poeple would run the turbo coupe or supra pcv's, is this what I need to do? What do I need to do to run one of those?

bimmertech · Nov 25, 2005

you could put a brake booster check valve in line as well. boosted air blows through the pcv and pressurizes the crankcase, that oil has to go somewhere.

that is just the way i understand it.

CManT1914 · Nov 25, 2005

An oil seperator is real popular on boosted cars because of the extra crankcase pressure. I know you've seen the threads, Andy has a good one that just resurfaced lately. Check it out, it's cheap and it will catch all that nasty oil that gets through the crappy PCV valve.

HISSIN50 · Nov 25, 2005

I would make some mods to the system, as you suggested, given that you run 12 PSI.

Good luck.

rustang94 · Nov 25, 2005

When you have boost dont you reroute the pcv system out of boost?? I did a procharger on a 350z and they had me run the pcv hose to the airfilter side of the blower.

BlackVert · Nov 25, 2005

with a kenne-bell, you connect the pcv to the vacuum side, so i guess it won't be an issue for me, sorry.

i'd put a check valve in at the very least.

BlueOvalStangGT · Nov 26, 2005

Where can I get that? Thats just a one way valve that I would but on all my vac. lines that see boost that shouldnt?

a50sn95 · Nov 26, 2005

I'm not sure I follow how a separator keeps oil out of the intake on a S/C car.
My assumption is that the PCV system is hooked up like stock (Meaning no breather on the V/C). Under no-boost situations, the pcv lets air flow from the crankcase INTO the upper intake. If you have the baffle and oil screen in place, this should keep oil out of the lines. Only if you have severe blow-by can I see oil getting into the intake. Meaning you have lots of crankcase pressure forcing it's way past the system.
Under boost, the airflow is actually going the other way - towards the crankcase. So, how would this get oil into the oil seperator? Where is this oil coming from?
The only path I can see to oil in theintake is that if boost gets past the PCV valve, you are pressurizing the crankcase, and the only path for this to go is back through the hose in valve cover fill tube into the Supercharger inlet tube. If you have V/C's without baffles, this could bring oil with it, and then you'd have oil throughout your intake path. This is why people use the Supra or Turbo coupe PCV valve, or a one-way valve (brake booster valve...).
Since I had oil in my intake before I rebuilt my engine, I stuck a seperator in the PCV hose, like is posted on here. I have well over 2000 miles, and several strip passes, and have yet to see any oil in my seperator.
I can only assume that oil in a seperator is coming from the intake baffle and/or screen missing, running a breather (which compared to the tiny little hole the stock PCV system draws through could allow more air flowing faster through the PCV valve and keep the baffle/screen from removing all the oil), or a significant amount of blow-by.
So, does anyone have a good explanation of how boost gets oil in the intake? Or, point out a flaw in my understanding of how the system works?
Dennis

blk9450 · Nov 29, 2005

BlackVert said:
with a kenne-bell, you connect the pcv to the vacuum side, so i guess it won't be an issue for me, sorry.

i'd put a check valve in at the very least.

yea we all know that you are getting a kb. 90% of your posts have you advertising that you are getting one. this post is worthless except to notify everyone yet again. you can shut up now:Teh-Win:

VibrantRedGT · Nov 29, 2005

A little oil in the upper is fine even without a power adder. If it's everywhere and trying to go back towards the TB then that's an issue. An oil seperator worked well for me when I had a blower. Its the easiest way to keep oil away from parts that don't require it. Steeda sells a complete kit for $60 I believe. Or you can peice one together at a local auto parts store for under $20. This is basically a bandaid fix. The real fix is a race set up (ex. Down's Ford) which includes valve covers, double breathers, PCV cap and plumbing.

BlackVert · Nov 29, 2005

blk9450 said:
yea we all know that you are getting a kb. 90% of your posts have you advertising that you are getting one. this post is worthless except to notify everyone yet again. you can shut up now:Teh-Win:

sorry, i didn't realize i was coming across like a dick.

i promise i'm not trying to be an a-hole about it. it's just that i'm pre-occupied with it because i'm in the middle of trying to finish up installing it.

DougNuts · Nov 29, 2005

a50sn95 said:
So, does anyone have a good explanation of how boost gets oil in the intake? Or, point out a flaw in my understanding of how the system works?
Dennis

IIRC, When you're under boost, the PCV valve should be closed due to the pressure coming from the intake side. But, you will also have increased blow-by due to the boost. When you come out of boost and the intake sees vacuum, the PCV valve should partly open and will then vent the now pressurized crankcase, along with some oil vapors, back into the intake.

That's only my analysis of how boost would work on a stock PCV system. As stated, many boosted applications change the routing of the PCV system. I personally wouldn't vent it upstream of a turbine, but that's how you could keep it working as stock.

In a N/A application, WOT is when the valve is open the most. More vacuum = more open PCV.

BlackVert · Nov 29, 2005

does a normally functioning pcv valve seal all the boost off, or could some boost could get in through there anyway?

blk9450 · Nov 29, 2005

DougNuts said:
In a N/A application, WOT is when the valve is open the most. More vacuum = more open PCV.

actually you shouldnt have much vacuum at wot, closing the throttle from a high rpm will have the most vacum. but i guess blowby at wot would create a higher relative vacuum.
what do i know im all doped out on cough meds

94TURBO5 O · Nov 29, 2005

Keven are you using a breather on your oil spout and what are you doing with the nipple running off of it?
FWIW
I had to run a race set up on mine like the Downs system.
It's an Evac canister(catch can) and lines/hoses that run out of the vc's.

BlueOvalStangGT · Nov 29, 2005

94TURBO5 O said:
Keven are you using a breather on your oil spout and what are you doing with the nipple running off of it?
FWIW
I had to run a race set up on mine like the Downs system.
It's an Evac canister(catch can) and lines/hoses that run out of the vc's.

It was plugged, now its gone and I run a breather on the V/C, and a Breather on the PCV.

94TURBO5 O · Nov 29, 2005

This is what I ended up running.
https://shogunindustries.com/cgi-bi...9084430044&page=products.htm&view_item=E42798

https://shogunindustries.com/cgi-bi...4430044&page=products.htm&view_item=FC62601-1

94TURBO5 O · Nov 29, 2005

My breather started getting saturated with oil and leaking onto my headers. I went back to a sealed cap and run a line from the vc to the evac can.
I run a turbo coupe pcv.

94GTLaserRC · Nov 30, 2005

VibrantRedGT said:
A little oil in the upper is fine even without a power adder. If it's everywhere and trying to go back towards the TB then that's an issue. An oil seperator worked well for me when I had a blower. Its the easiest way to keep oil away from parts that don't require it. Steeda sells a complete kit for $60 I believe. Or you can peice one together at a local auto parts store for under $20. This is basically a bandaid fix. The real fix is a race set up (ex. Down's Ford) which includes valve covers, double breathers, PCV cap and plumbing.

I think theyre as low as $30's on Ebay...still more than getting it yourself, but will save you a little time (and a little aggravation is the first place you go doesnt have all the parts)
RC

BlueOvalStangGT · Nov 30, 2005

JR, your links are expired.

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