"The BIG BOV thread" (Where all bov question threads get merged) - Page 765
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This is a discussion on "The BIG BOV thread" (Where all bov question threads get merged) within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; Originally Posted by SD_GR Generally, yes, I've yet to see an intake that works better than stock. If one did ...

  1. #11461
    Registered User teflon_jones's Avatar
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    Quote Originally Posted by SD_GR View Post
    Generally, yes, I've yet to see an intake that works better than stock. If one did I'd be interested, why not, but so far, not much out there.
    If somebody somehow invents a miraculous, impossible intake like that it would be very interesting!

    It's not really impossible but you'd basically have to use a regular paper filter but a larger one than stock in order to increase airflow, along with a (effectively) larger, smooth hose like the aftermarket ones use. I've honestly never even thought about doing that but you raise an interesting question. There's a ton of paper filters on the market that are a lot bigger than a stock Subaru filter so it comes down to being able to build an airbox to accommodate one. This gives me an idea I want to try out now.....
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  3. #11462
    Registered User Impreza2.0's Avatar
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    You will still be stuffing that air into the same sized tube. Better to cool it than try to open it up.
    The intake filter doesn't have to be replaced in some cases, the convenience outweighs the performance argument for some.

    Quote Originally Posted by teflon_jones View Post
    If somebody somehow invents a miraculous, impossible intake like that it would be very interesting!

    It's not really impossible but you'd basically have to use a regular paper filter but a larger one than stock in order to increase airflow, along with a (effectively) larger, smooth hose like the aftermarket ones use. I've honestly never even thought about doing that but you raise an interesting question. There's a ton of paper filters on the market that are a lot bigger than a stock Subaru filter so it comes down to being able to build an airbox to accommodate one. This gives me an idea I want to try out now.....

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    Pro Manscaper Mikie13's Avatar
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    Quote Originally Posted by Impreza2.0 View Post
    You will still be stuffing that air into the same sized tube. Better to cool it than try to open it up.
    The intake filter doesn't have to be replaced in some cases, the convenience outweighs the performance argument for some.
    The air that comes from the stock intake is technically cool. The ram-air scoop in the front goes into the wheel well where the silencer is, and then to the filter element. It virtually runs a similar path as any aftermarket CAI.
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  5. #11464
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    Quote Originally Posted by Impreza2.0 View Post
    You will still be stuffing that air into the same sized tube. Better to cool it than try to open it up.
    The intake filter doesn't have to be replaced in some cases, the convenience outweighs the performance argument for some.
    Not necessarily.

    CAI; AEM or K & N


    Quote Originally Posted by zax View Post
    Justin prompted me to do a little study about intake temperatures just to satisfy my own curiousity.

    Suppose we take the ambient temperature to be 30 degrees F (Tenv).

    The initial intake temp registered by the MAF for the stock intake box may be 70 degrees F.

    The initial intake temp registered by the MAF for the CAI may be 40 degrees F.

    In a perfect scenario, the intake charge will undergo 3 temperature stages:
    1. initial intake temp (T0)
    2. Temperature post-turbocharger (Tb)
    3. Temperature into the cylinders (Tc)
    and we'll stop there (pretend that there is no excess heat from internal combustion)

    In this perfect scenario, the intake charge undergoes an adiabatic compression by the turbocharger. This heats the incoming air by the same amount no matter the intial intake temp. To be reasonable, let's call this 190 degrees F.

    Now Tb = 230 F for the CAI and Tb = 260 F for the stock airbox

    The intake charge will now enter the intercooler where it will dwell for some time. When air is flowing through the intercooler, it will undergo forced convection cooling. The equation for this cooling is

    T(t) = Tenv + (T0-Tenv)exp(-rt) where t = duration of cooling and r is a constant that depends on the fluid dynamics and area of interface between the two heat-exchanging materials (intercooler size). For our purposes, we will take r*t=1 but we could calculate this in practice by taking the air consumption of the engine and size of the intercooler into account.

    So for our study, Tc = 103.5759 degrees F for the CAI and Tc = 114.6123 degrees F for the stock airbox.

    So, even though we started with a 30 degree F intake charge temp. difference, we only ended with an 11 degree F difference when the intake charge enters the cylinders. So the CAI will make difference, albeit somewhat less than with a N/A car.

    EDIT:
    If we increase the area of the Intercooler by 33% (in perfect scenario) for the stock airbox setup, Tc drops to 90.829 degrees F, which is less than the CAI with stock intercooler
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  6. #11465
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    need new BOV.

    So i have been having this problem, boost usually reads 16psi now only read around 5 to 7psi, ppl been saying boost leak, but i took to subaru dealer and they said my awesome EBAY BOV the previous owner bought, is faulty. so now im in the market for a new one. im looking at either PERRIN or a turboXS rfl BOV. which of the 2 would be better?

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    Quote Originally Posted by TurboScubi View Post
    So i have been having this problem, boost usually reads 16psi now only read around 5 to 7psi, ppl been saying boost leak, but i took to subaru dealer and they said my awesome EBAY BOV the previous owner bought, is faulty. so now im in the market for a new one. im looking at either PERRIN or a turboXS rfl BOV. which of the 2 would be better?
    If your choice is Perrin or TurboXS...now doubt Perrin. Much better quality. We sell them as well.

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    Quote Originally Posted by TurboScubi View Post
    So i have been having this problem, boost usually reads 16psi now only read around 5 to 7psi, ppl been saying boost leak, but i took to subaru dealer and they said my awesome EBAY BOV the previous owner bought, is faulty. so now im in the market for a new one. im looking at either PERRIN or a turboXS rfl BOV. which of the 2 would be better?
    What year is your car and what mods does it have?
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    Quote Originally Posted by TurboScubi View Post
    So i have been having this problem, boost usually reads 16psi now only read around 5 to 7psi, ppl been saying boost leak, but i took to subaru dealer and they said my awesome EBAY BOV the previous owner bought, is faulty. so now im in the market for a new one. im looking at either PERRIN or a turboXS rfl BOV. which of the 2 would be better?
    Find the stock BPV.
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  10. #11469
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    Quote Originally Posted by TurboScubi View Post
    So i have been having this problem, boost usually reads 16psi now only read around 5 to 7psi, ppl been saying boost leak, but i took to subaru dealer and they said my awesome EBAY BOV the previous owner bought, is faulty. so now im in the market for a new one. im looking at either PERRIN or a turboXS rfl BOV. which of the 2 would be better?
    I might have a stock BPV that I can provide.

    However, this does not sound like a boost leak. 7 PSI is wastegate pressure. There are a number of reasons why you might only be achieving wastegate pressure:
    1.) The car has mods for which it is not properly tuned.
    2.) If you retained the stock EBCS, you may have significant detonation resulting in your ECU pulling boost.
    3.) If you have an MBC (not recommended), the spring actuator may have failed, resulting in full bleed and wastegate pressure
    4.) You have removed the restrictor pill from the stock EBCS vacuum plumbing
    5.) Your wastegate and boost control vacuum plumbing is not properly connected or there is a boost leak.

    I have easily snapped the stock vacuum plumbing for the EBCS system, so you might want to start checking there.


    Back on topic, however, if you are on the stock turbo (from your profile is a TD04-13T) you will benefit the most from the stock BPV. PM me if you are interested.
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    02, 3" full catless exhaust, K&N Intake. not too sure of whatelse.

  12. #11471
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    I can tell you with almost certainty what happened. You bought this car used. The previous person modified it. They tuned for it. They wanted to sell it. They sold their manual boost controller and hooked up the old vacuum hose. But they had taken the restrictor pill out of it because they didn't use it with the boost controller. Now your car is tuned for a manual boost controller, but you don't have one in.

    It's not 100%, but I've had about 10 guys that have had this problem over the past couple years that I've helped fix it.

    The only way to be sure if I'm not lying to you is... Get someone with a tactrix cable (or if you have an accessport) download logs, and see if your WGDC (wastegate duty cycle) is 0. If it is... then what I said is correct, and you can either put a MBC on the car, or have the car's tuning adjusted after you install a restrictor pill. ALSO... make sure your vacuum hose DOES have the restrictor pill in it. Some idiots don't tune for the MBC, and just pull out the restrictor pill, and throw a MBC on it.

    DONT install a manual boost controller without checking on this first. You might make problems worse if I'm not correct.
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  13. #11472
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    Bov

    Looking to get a bov what one is the best to run on a 2.2 with an 18t bloushe turbo?

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    Merging your thread with the "Big BOV thread"
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    Quote Originally Posted by zax View Post
    Merging your thread with the "Big BOV thread"
    my dream job.....

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    Quote Originally Posted by wrxtreme06 View Post
    my dream job.....
    go merge your own threads!
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