Synjn

iTrader: (1)

[QUOTE=rcdash;8548759]Looks like it's designed for fuel/oil - much heavier materials than the plastic counterparts. While they may work fine, the lighter check valves designed for brake booster operation seem to work just fine.



Rcdash - could you post a link to website for check valve that you recommend I can purchase.

rcdash

iTrader: (18)

[QUOTE=Synjn;8553736]Mine looks like this (I got mine out of a drawer at Forged Performance though):

http://www.frsport.com/Nissan-OEM-S1...e_p_15267.html

str8dum1

iTrader: (11)

or a little cheaper here
http://www.courtesyparts.com/47478-v...2_883_982_989&

wannabuy350z

iTrader: (27)

This set-up seems to be the best so far, but one thing comes to mind. since we are always trying to extract vapor from the crank case. but dont the vavle and cams need some type of fluid to ease friction?

after using this set-up RCDASH have you opened the vavle cover and checked to see if there is any oil or is in just clean dry?

binder

iTrader: (8)

How are you guys running that 5/8" hose from the drivers valvecover? Do you just get a huge piece of 5/8" hose or are you stepping it down to a 3/8" hose like the others? That 5/8" hose is just a pain to run around in the engine compartment.

weslutes

iTrader: (7)

Crank case pressure and oil pressure are separate. Filtering/venting crank case vapors does not effect lubrication.

HotRodG35

iTrader: (7)

If you use the OEM hose from the driver side valve cover its preformed enough to allow the 5/8 hose to attach using double ended male nipple.

Didn't you run a Vortech at one time ? Its the same mod.

I now use all AN fittings with braided steel lines and still able to maintain 10 AN line.

HotRodG35

iTrader: (7)

I have no issues, it was bench tested to 20# air press with no leakage. Able to withstand oil, preventing the valve diaphragm from deterioratating like standard check valves.

My other motivation was I use all AN fittings and braided steel lines and didn't want to use hose clamps.

binder

iTrader: (8)

i never used that line into my vortech. I personally didn't like the idea of pumping nasty vapors and oil into my charge pipes.

I have mine set with a filter, but it's on the drivers side. Trying to route it behind the engine and around to the passenger side where my catch can is creates a problem with that 5/8" hose. I'd like to use just a 3/8" hose like my passenger side.

HotRodG35

iTrader: (7)

I can see how you would have trouble running a 5/8" line behind engine.

I ended using a MOROSO breather tank on driver side, and a greddy catch tank for the PCV return on passenger side, it seems overkill but eliminated all the issues of blow-by and oil build up inside intake.

rcdash

iTrader: (18)

The hole on the driver's side valve cover opening is situated toward the bottom, which means that if you have a small elbow with just a breather, oil will drain straight back down into the valve cover. So a breather tank is unnecessary. I used a bit of preformed 5/8" hose which angled back and up at a 45 degree angle. Then a 5/8" to 1/2" reducer and then just put the breather on top of that to keep it all compact. It all fits below the neck of the plenum.

binder

iTrader: (8)

ya, i have a breather on the end of the oem line right now.

It was angling downwards to the drivers side but oil was coming out so i moved it to the passenger side to pointupwards again like i had it before my return fuel system. PITA to get it over there without removing the plenum. I think it'll be ok now but i need to find a better way to anchor it.

On a brighter note, car is back together and the oil drain issue is fixed!

Synjn

iTrader: (1)

So I have a bottom line question regarding performance with an FI'd application:

Which setup should provide more hp?

A: Open breathers all the way around, on both valve covers. For example, at this moment I have 4 small breathers total. 2 on passenger side and 2 on driver side (I removed the center crossover vents and put breathers on them.)

Pros-never contaminating the intake charge with dirty vapors.

OR

B:Manifold vacuum recirculation (in any shape or form, w/ a catch can of course)

Pros-Better piston ring seal


Additional question: When under high boost is CC pressure + or - when using the pre- boost intake vacuum source. As far I have read that vacuum source never exceeds 1"hg (.5 psi) or so. I'm assuming CC pressure is greater than that, thus will overtake the pre boost vacuum source, so what is the point of using it? Instead of pulling, the CC is going to actually be pushing right into my intake ---> intercooler ----> throttle body etc.

http://www.k20a.org/forum/showthread.php?t=24360

Reading this just confuses me more. From what i've gathered here is that unless you can create a significant vacuum of 14"hg(7psi) or more during high load/wot conditions, which we cannot, you are not scavenging whatsoever. Not making any gains.

I wish someone could explain to me how "good piston ring seal" at idle is going to unlock hp? I need "good piston ring seal" when my foot is on the gas, not idling. And since we can't create a vacuum in the CC when at wot (foot on the gas), how is this supposed to work?

Here is the most descriptive/current write-up I could find. Read me!
http://www.sr20-forum.com/all-motor/...d-edition.html



I'm so ready to move past this.

HotRodG35

iTrader: (7)

Not sure who your referring to. My set up has a 1/2 NPT adapter on rear of driverside valve cover with a 10 AN line on a continuos down slope to breather tank located on driver side frame rail just forward of wheel well liner. Than another line from breather tank to air filter.

This will allow crankcase vapors to vent under boost without contaminating intake, prevent crankshaft seal failure and allow for proper piston ring sealing.

HotRodG35

iTrader: (7)

I would go with setup (B). Having just breathers is not going to help keep crankcase properly evacuated. Plus this will eventually lead to oil on areas near the breathers.

I did not read the long winded write up. Basically you need two ways to vent crankcase.

First method is while car is idling or under vacuum cruising the crankase vapors will be drawn thru PCV check valve and into the intake. Most people install a catch tank between PCV check valve and intake to seperate oil to minimize contamination of intake.

Second method is used under low vacuum, vapors are vented from back of driver side valve cover thru hose to air filter box. The vapors will be drawn into air filter to help maintain crankcase vent. In this situiation the PCV check valve closes to prevent pressurizing crankcase thru valve covers, especially critical with boosted applications.

In both methods above the vapors collected in either valve cover can be vented because of the crossover line.

Circle track cars use belt driven vacuum (evacuation) pumps to help minimize crankcase pressures due to blow by, because of the obvious WOT and high compression.

Drag racing uses an eductor method (attached to header collectors) to vent out crankcase gases under low vacuum.

Hope this helps some, try not to be confusing.

rcdash

iTrader: (18)

My post was just a general observation that a little elbow and compact setup will obviate the need for a breather tank and long lines.

synjn, you are correct that we do not have access to an ideal vacuum source during boost. The best we can really hope to achieve is 0 psi in the crankcase (without a mechanical vacuum pump as hotrodg35 mentioned).

Synjn

iTrader: (1)

Well here is where i'm at so far:

This is the design I have come up with. My focus here is to create a neg pressure that travels completely through the bottom end. In my mind it is the only way to, "suck the pistons down" if you will, and get improved piston ring seal and prevent oil being pushed up the cylinder wall. The red indicates a check valve, the arrow = flow direction.


I am not finished as you can see i need to add a check valve and breather to the passenger crossover port. For testing purposes I just plugged the hose


The drivers side has 2 breathers as you can see. One attached directly to the valve cover crossover port and the other attached to a shortened 5/8 hose.


The pre-boost intake I have plugged. Simply shaved off a wine bottle cork to plug into the elbow until I find a better way to seal it. This is a terrible vacuum source that only works a wot for the most part. About 1 in/hg from what I have read, I have yet to confirm. Not nearly enough to PULL when the CC is at its greatest PUSH. This guy is never going to create a vacuum in the CC. You'd be better off cutting the line off and putting a breather making it easier for the CC to release pressure. The longer the hose, the more difficult it is to breathe.


Initially I had drilled out my oem pcv valve as I had heard so much about. Only to find out after one 5 min drive that I was burning oil badly, as indicated by huge white smoke cloud and oil marks on the driveway coming out the exhaust.
I went a bought a new oem check valve and decided to log the difference in vacuum @ the catch can between the two.


What I found was:

OEM pcv = 15 in/hg @ idle (with little oil accumulation in catch can)

Drilled out pcv = 7 in/hg @ idle (running for less than 30sec oil was already rapidly filling the catch can).

Which tell me that the pcv valve is acting as a vacuum regulator as well as a check valve. (Which most of you already know). I thought at first the pcv would open up all the way under high vacuum, then I came across this.

Engine off/backfire --- Low load/Idle --- Medium Load/cruising --- High load/WOT
0 /positive pressure---Highest Vacuum--- Moderate Vacuum ---- Slight Vacuum
PCV Valve closed ---- PCV open slightly-- Valve opens more --- Open all the way

The first line shows load, second line pressures seen in the Intake manifold, and third line is how the PCV valve responds.



It's an old thread but informative read
http://www.honda-tech.com/showthread.php?t=697498

Conclusion so far: Don't mess with the oem pcv.

I'll keep updating. I have yet to drive around on this setup.

binder

iTrader: (8)

I'm on board with your theory of the vac source being not near enough to cause a difference in CC ventilation.

If the CC is under 5psi or so of pressure under boost then it will push that pressure out the vents. The vac source is only pulling .5psi or so which means that the air is actually being FORCED into the vac source by the CC pressure. .5psi drop in cc pressure isn't worth the extra trouble of the lines and cost for me to build a system.

rcdash

iTrader: (18)

If you drill out the PCV and then ventilate through the bottom end as you indicated, I'm not surprised you pulled out so much oil (as predicted in post #157 ). The fuel and water vapors will remain above the oil. Don't try to ventilate through the bottom end and your drilled out PCV will work much better. Alternatively you need to restrict manifold vacuum (as the PCV does). The problem with the OEM PCV is that it can eventually clog and/or allow boost to flow back into the crankcase (both undesireable).

I agree that messing with the turbo intake seems like a lot of hassle for little gain (so long as you don't mind running an open breather).

binder

iTrader: (8)

so will i have problems with an open breather if i drill out the pcv? will i even gain anything from drilling it out?