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  1. #1
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    PCV Vent to Atmosphere?

    I know a lot of work was done on this, and I seem to remember dzenno and rob beck saying it was a bad practice. Does anyone remember if it's true and why / how / etc?
    LEMANS BLUE M-TECH E92->PROCEDE REV3::ETS 7" FMIC::RACELAND DPS::WAVETRAC DIFF::DEFIV DIFF LOCKDOWN::DEFIV OCC::DEFIV INTAKE::RB PCV

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    Have it on the Stage 3 car, have done it on I cant even count how many cars. It is not really a problem, running hybrids or stage 2 type turbos you will prob smell it as they tend to burn a little oil. On the stage 3 car, it goes to an OCC, then out to a K&N PCV filter of pretty good size. With close too 1000 WOT pulls and thousands of miles of driving with the cowl filters off I have not smelled it, and the filter is completely free of oil, I have drained the OCC twice both times getting about 1/4" of oil out of it. Maybe this is just a good running, tight motor, or maybe these Garrett GT series just really control oil well. Either way, in my experience its been fine. We will be routing in back into the intake on the production kits, but you can run it this way with no issues.

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    All of the catch cans on the market only catch oil from vapor traveling from the crankcase to the rear turbo intake tube. The blow by gases take this route if there is positive pressure in the intake manifold relative to atmospheric pressure.

    They do nothing for vapor traveling from the crankcase to the intake ports on the head in cases where there is negative pressure in the intake manifold. This is the primary cause of the dirty intake valve in my opinion.

    Short of putting a hole in the valve cover and blocking off the flow of gasses through the stock cyclonic separators, there is no solution to this.

    So even if you vent your blow by to the atmosphere, the valve cover will still route blow by into the intake ports when there is negative pressure in the intake manifold.

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    Interesting, I seem to remember that there was something said about VTA causing increased smoking/oil consumption for whatever reason.
    LEMANS BLUE M-TECH E92->PROCEDE REV3::ETS 7" FMIC::RACELAND DPS::WAVETRAC DIFF::DEFIV DIFF LOCKDOWN::DEFIV OCC::DEFIV INTAKE::RB PCV

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    Click here to enlarge Originally Posted by uniter Click here to enlarge
    Interesting, I seem to remember that there was something said about VTA causing increased smoking/oil consumption for whatever reason.
    The whole PCV system is kind of confusing. Like why do you need an additional air/oil separator like the BMS OCC when there are four air oil separators integrated into the valve cover? Nothing against Terry, his product works as intended, but it should not even be necessary.

    I don't really see why VTA would cause additional smoking itself. If you look at the layout, the PCV tube that goes into the rear intake tube is like six inches from a DCI filter, if your vehicle is so equipped. So if the stock layout doesn't cause smoking itself, why would a direct VTA filter? The only reason I could think of is because the oil is never being properly separated, so with the stock system that tiny bit of oil vapor gets sucked into the turbo and burned in the engine. With VTA, that oil vapor is making it directly to the atmosphere.

    I think BMW sorta dropped the ball on the N54 PCV system, specifically separating the blow by gasses from the oil vapor. This has greater implications than just dirty intake valves as oil in the charge air will lower the effective octane of the air fuel mixture. That is the opposite of what we want.

    I'm looking into alternate solutions, because I was having bad smoking problems once I installed my catalyst free down pipes.

    Once I have something concrete, I'll post my findings.

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    The PCV system can be important in certain cars, first getting the nasty gasses that can corrode and do other bad things inside the engine, second it creates a vacuum. In theory the higher vacuum you can create helps seal rings and eases the movement of parts that would normally have to move through the air such as the crank and rods. In the real world not sure how much this matters maybe as much of a difference as the people who block of EGR or Throttle Body coolant hoses. Some people have gone as far as to hook up a PCV system to the exhaust creating a venturi effect to get as much vacuum in the crank case as possible. As for BMW's system being bad it's about as effective as most other cars systems I've seen, they get the gasses out and leave a mess in the intake just like most others.
    2008 135i - Cobb AP, JB4 G5 w/2Step&FSB, MS DP's, Berk street exhaust, AMS IC, VTT Inlets, UR Intake, ER CP w/Tial BOV, Spec 3+ & Steel FW, CDV delete, Quaife LSD, DSS Axles, M3 control arms, M3 rear SF bushings, M3 Trans bushings, SS brake lines. Pics

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    Click here to enlarge Originally Posted by brusk Click here to enlarge
    The PCV system can be important in certain cars, first getting the nasty gasses that can corrode and do other bad things inside the engine, second it creates a vacuum. In theory the higher vacuum you can create helps seal rings and eases the movement of parts that would normally have to move through the air such as the crank and rods. In the real world not sure how much this matters maybe as much of a difference as the people who block of EGR or Throttle Body coolant hoses. Some people have gone as far as to hook up a PCV system to the exhaust creating a venturi effect to get as much vacuum in the crank case as possible. As for BMW's system being bad it's about as effective as most other cars systems I've seen, they get the gasses out and leave a mess in the intake just like most others.
    Essentially the ideal solution then is to have a downpipe such as Macht Schnell with the EGT bung, no cats in the midpipes, and a hose hooked up to the bung from the check valve, with the turbo inlet pipe capped off?

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    No clue I've never seen any real results of how much of a difference any of this makes. Will not having vacuum create a nasty crank case? Will extra vacuum actually boost ring seal and lower wind drag to the point of making any difference? regardless the oil that gets past the OEM system has to go somewhere, OCC, Intake, Exhaust no clue what's the best way is but I guess in theory a vacuum pump and OCC or exhaust and OCC would be the best performance option. I know this was talked about in different threads before and I remember somebody showing a nice setup of a Vette maybe that had some vacuum system hooked up.
    2008 135i - Cobb AP, JB4 G5 w/2Step&FSB, MS DP's, Berk street exhaust, AMS IC, VTT Inlets, UR Intake, ER CP w/Tial BOV, Spec 3+ & Steel FW, CDV delete, Quaife LSD, DSS Axles, M3 control arms, M3 rear SF bushings, M3 Trans bushings, SS brake lines. Pics

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    I was under the impression the positive pressure from the burning air fuel mixture was primarily responsible for sealing the rings to the cylinder walls.

    Do you really think vacuum in the crankcase will reduce wind drag on the rotating assembly an appreciable amount?

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    Oh boy Click here to enlarge have you not heard of the PCV saga threads? lol i don't like linking to other forums but i used to be on one of those a long while back and had a thread on the topic go to great lengths with discussion and experimentation...check these out, plenty of info:

    http://www.e90post.com/forums/showthread.php?t=518306

    Some of it is on n54tech as well:

    http://www.n54tech.com/forums/showth...980#post179980
    Click here to enlarge

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    Click here to enlarge Originally Posted by ajm8127 Click here to enlarge
    I was under the impression the positive pressure from the burning air fuel mixture was primarily responsible for sealing the rings to the cylinder walls.

    Do you really think vacuum in the crankcase will reduce wind drag on the rotating assembly an appreciable amount?
    I've seen websites say 15+ HP when proper crankcase vacuum is achieved. Not sure how much is needed and for what engines. Engine manufacturers have gotten pretty good over the years and some of the racing tricks to make things a little more efficient so every engine will vary. Considering the aftermarket choices of windage trays, crank scrapers, crankcase vacuum pumps and systems there might be something there to look. Machine shops have also been known to recommend knife edging/crank shaping to add extra HP. But some of these might just be that they worked good on a small block or the racer with extra money to spend trying to find that last 5-10HP for a slight advantage. Unless somebody is actually able to go through the hassle of testing one of our cars then who knows.
    2008 135i - Cobb AP, JB4 G5 w/2Step&FSB, MS DP's, Berk street exhaust, AMS IC, VTT Inlets, UR Intake, ER CP w/Tial BOV, Spec 3+ & Steel FW, CDV delete, Quaife LSD, DSS Axles, M3 control arms, M3 rear SF bushings, M3 Trans bushings, SS brake lines. Pics

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    Aside from a vacuum pump we are taking about such a low amount of vacuum that I just can't imagine it matters when cylinder pressures are in the hundreds if not thousands of psi during the power stroke. This isn't the pressure seen during a compression test, but the pressure created by the burning air fuel mixture.

    The only system I would advocate is a closed system that returns the oil to the crankcase ( like the stock system) and routes the gasses through the stock valves. That is because my goal is effective separation which the stock system does not do.

    Even if you wanted to use a vacuum pump, you still need to effectively remove the oil from the gasses.

    I've read the threads on pcv and I have an RB pcv valve. What I really need is an effective way to separate the oil from the gasses, and that is what I am working on.

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    Click here to enlarge Originally Posted by ajm8127 Click here to enlarge
    All of the catch cans on the market only catch oil from vapor traveling from the crankcase to the rear turbo intake tube. The blow by gases take this route if there is positive pressure in the intake manifold relative to atmospheric pressure.

    They do nothing for vapor traveling from the crankcase to the intake ports on the head in cases where there is negative pressure in the intake manifold. This is the primary cause of the dirty intake valve in my opinion.

    Short of putting a hole in the valve cover and blocking off the flow of gasses through the stock cyclonic separators, there is no solution to this.

    So even if you vent your blow by to the atmosphere, the valve cover will still route blow by into the intake ports when there is negative pressure in the intake manifold.
    after pulling my engine apart... it's super SUPER oily on the rear intake, the intercooler piping, the charge piping

    i'm 99% confident the gummed up intake valves would be pretty much from that - non OCC'd blowby.

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    Click here to enlarge Originally Posted by Flinchy Click here to enlarge
    after pulling my engine apart... it's super SUPER oily on the rear intake, the intercooler piping, the charge piping

    i'm 99% confident the gummed up intake valves would be pretty much from that - non OCC'd blowby.
    Valveguides leak some amount of oil over time. People tend not to consider that as well. I'm sure some of the crap we see in the intake ports is from oil vapor from PCV but I suspect a good amount is valveguide oil too. If the guides loosen a bit from wear, you'll get even more.

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    Click here to enlarge Originally Posted by dzenno@ProTUNING Freaks Click here to enlarge
    Oh boy Click here to enlarge have you not heard of the PCV saga threads? lol i don't like linking to other forums but i used to be on one of those a long while back and had a thread on the topic go to great lengths with discussion and experimentation...check these out, plenty of info:

    http://www.e90post.com/forums/showthread.php?t=518306

    Some of it is on n54tech as well:

    http://www.n54tech.com/forums/showth...980#post179980
    Oh yeah, I've read through them. I have an aversion to information buried in massive threads Click here to enlarge

    @E90Company: the venturi jet has to be installed at a specific angle to the exhaust gasses, so you can't use the EGT bungs. Kits show up with weld-in bungs.
    LEMANS BLUE M-TECH E92->PROCEDE REV3::ETS 7" FMIC::RACELAND DPS::WAVETRAC DIFF::DEFIV DIFF LOCKDOWN::DEFIV OCC::DEFIV INTAKE::RB PCV

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