"The BIG BOV thread" (Where all bov question threads get merged) - Page 294

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; performance loss????? you just don't get it do you. it does nothing to aid or to hinder your performance. what ...

  1. #4396
    Registered User
    Join Date
    Dec 2003
    Posts
    479
    performance loss????? you just don't get it do you. it does nothing to aid or to hinder your performance. what it does is run rich and kill your uppipe cat causing it to break free and fly into your turbo. thats a bad thing.

    oh and running lean with an intake isn't fun either. both of those together do bad things.

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #4397
    Registered User
    Join Date
    Oct 2004
    Posts
    128

    depends guys, and your changing the post title

    i am running the apexi dual funnel intake system, it is supposed to not let the car run lean or rich but correctly, it does this by a plate that directs air into the mass air flow sensor, all i know is that i bought this intake because its not supposed to mess anything up, all i know is my car runs perfect, did a 0-100mph in front of my friend he says he saw no smoke whatsoever, btw he is dam near blind lol, my other friend watched and said it was a very SLIGHT black exhaust, which is good, my advice is get the APEX I intake and exhaust cause it sounds awesome. btw i gotta have a friken leak somewhere,

  4. #4398
    Registered User
    Join Date
    Oct 2004
    Posts
    128

    ok guys, what gives

    i spent all night out listening to my car, it doesnt sound like its really coming from any one point the thing is that at a steady rpm there is no zing zing, it seems to only make its presense when you rev it up not held constant but when reved, it is VERY LOUD it is of equal sound level as the exhaust, and pulses with the exhaust i mean its retarded loud, i got to thinking, i wonder if its the exhaust resonating the flex pipe at a certain frequency? jesus will someone please put these on there car and tell me, im sick of being the only person on the board with these ****ers.

  5. #4399
    Registered User
    Join Date
    Dec 2003
    Posts
    479
    i think im getting them as long as i can get the work done at precision tuning and that they don't tell me "they're junk" i think you might just be hearing the turbo and the wastegate flutter no?

  6. #4400
    Registered User
    Join Date
    Oct 2004
    Posts
    128

    possible

    its possible i mean it just seems like you can hear it all over, what i will say is that it resembles the sound of a BONE STOCK HONDA with no CATS, it doesnt sound like this out the back but just in the headers it sounds better than my analogy but similar, if that makes sense to anyone

  7. #4401
    Registered User
    Join Date
    Oct 2004
    Posts
    128
    raspy i guess

  8. #4402
    Registered User dviousboxer's Avatar
    Join Date
    Sep 2004
    Location
    FLORIDUH!
    Posts
    924
    i just put my airbox silencer back in with the ram airscoop. now it seems like its sounds like the way it sounded the first time. maybe i was just wasn't getting enough air or something like that. anyways thanks for the replies

  9. #4403
    Boba Fett BrianH's Avatar
    Join Date
    Oct 2003
    Location
    Way up high.
    Posts
    17,907
    take your hood off, it'll amplify the sound.

    or keep a kazoo in your cabin, blow it when you let off the gas. . . it's not as pimpin as the show off valve, but it works.

  10. #4404
    Registered User speelnik's Avatar
    Join Date
    Jun 2003
    Location
    the mullet godfather "TMR"
    Posts
    1,017
    ^
    yes!!!
    Former 03wrx, 04sti, 05sti, current 06civic
    "Teacher POWah"
    Team Mullet Racing
    BrianH is my biotch

  11. #4405
    Registered User ebr0t's Avatar
    Join Date
    Aug 2002
    Location
    U of Central Florida (Orlando)
    Posts
    15,307
    Quote Originally Posted by TheBoostCreep
    this thread gets The Bear and nothing more.....



    omg thats greatable.
    Quote Originally Posted by DTR rex

    Peter North > *

  12. #4406
    Registered User EtherealWRX's Avatar
    Join Date
    Oct 2004
    Location
    Downey
    Posts
    675
    Long live the The Bear! LOL

    Oh and....

    "Ma spoon is too big. Ma spoon is TOO BIG! ..... I AM A BANANA!!!"
    Have a Greddy Evo 2 cat-back Exhaust system, willing to trade for: Greddy Ti, Apex'I N1, or Apex;I GT cat-backs. California only! PM if interested!

  13. #4407
    Registered User
    Join Date
    Jan 2004
    Location
    MI
    Posts
    414
    Quote Originally Posted by burrito007
    performance loss????? you just don't get it do you. it does nothing to aid or to hinder your performance. what it does is run rich and kill your uppipe cat causing it to break free and fly into your turbo. thats a bad thing.

    oh and running lean with an intake isn't fun either. both of those together do bad things.
    No, I get it. I just think your reasoning is totally wrong and was giving you the chance to admit you really donít know/understand what your talking about before I explained (ill make a new post about this when I have some free time because this is a forum-wide problem).
    Very short-lived rich conditions are really not detrimental to your engine or catalytic converts. Turbo engines need to be rich to maintain temperature. The optimal a/f ratio is about ~13:1 to 14:1 (A: F). Now this should get you thinkin...
    Hey! That would cause catastrophic failure on our engines!
    Thatís right! So how do we manage the heat? Run very rich ~10:1-11:1
    If cats were extremely sensitive then our cars couldn't use them anyways.
    Here is where the misconception stems:
    The more rich a a/f mixture the more work a catalytic converter has to do, this creates more heat and wear on the cat because it is processing more. Cats also donít usually shatter apart when they are spent, they usually clog/restrict and smell awful. That will hurt performance but it should really never reach that point until many years of operation have past. Catalytic converters are not a wear item to be replaced frequently; they are pretty strong and last quite a long time under normal circumstances.
    Do you really think a BOV is going to affect the a/f more than say, a spark plug that has increased its gap .05 due to normal wear? Probably not. I donít have objective data (no a/f gauge) to back that up, but I know what I would put my $$$ on.
    On a side noteÖ
    Shouldnít you be trying to get the stock cats off anyways? They kill performance, I cant even believe how much getting rid of the stock cats helped my performance.

    The intake problem has a lot more merit (and that not saying much). You are altering a tuning device; however. You need to understand how a MAF works to understand why this isnít a huge problem for the ECU to compensate for the change in values.
    A Mass Air Flow sensor is a pretty simple design that heats wire so that them more air flowing into the intake and past the sensor, the cooler the wire will be. From this, you can start to apply it to all kinds of variables and hypothesis how they might affect youíre a/f ratio.
    A CAI will, theoretically generate lower values because more air can cool the heated wire. This is fine and dandy in theory, but often times a very hot engine bay caused by a turbo could heat the wire even more than possible under stock conditions. This causes a extra rich condition in some cases (not very harmful) and a lean condition; if and only if a) the ECU is getting readings out of its range (very unlikely, they are designed to run in the hottest desert and coldest tundra) b) the MAF is getting readings out of its range or c) the MAF sensor is not getting even flow of air and it is giving improper readings (less flow at the top of the intake and more at the bottom.
    The only logical argument is c and I really wouldnít buy it without a flow bench backing that up because if anything it is more even than stock.
    If any loss is noticed it is most likely because of heat soak created by a hot engine bay. Something easily combated by proper heat blocking/removal via heat shields.

    Iím sorry that I had to muck up this post I made about finding these cheap headers by explaining BOV and CAI but as you can see, that attitude is infectious and unfounded.
    I anxiously await your response

  14. #4408
    Registered User wrx&998rduck's Avatar
    Join Date
    Aug 2004
    Location
    Granada Hills Ca, north of los angele
    Posts
    356
    Quote Originally Posted by BigClunke
    No, I get it. I just think your reasoning is totally wrong and was giving you the chance to admit you really donít know/understand what your talking about before I explained (ill make a new post about this when I have some free time because this is a forum-wide problem).
    Very short-lived rich conditions are really not detrimental to your engine or catalytic converts. Turbo engines need to be rich to maintain temperature. The optimal a/f ratio is about ~13:1 to 14:1 (A: F). Now this should get you thinkin...
    Hey! That would cause catastrophic failure on our engines!
    Thatís right! So how do we manage the heat? Run very rich ~10:1-11:1
    If cats were extremely sensitive then our cars couldn't use them anyways.
    Here is where the misconception stems:
    The more rich a a/f mixture the more work a catalytic converter has to do, this creates more heat and wear on the cat because it is processing more. Cats also donít usually shatter apart when they are spent, they usually clog/restrict and smell awful. That will hurt performance but it should really never reach that point until many years of operation have past. Catalytic converters are not a wear item to be replaced frequently; they are pretty strong and last quite a long time under normal circumstances.
    Do you really think a BOV is going to affect the a/f more than say, a spark plug that has increased its gap .05 due to normal wear? Probably not. I donít have objective data (no a/f gauge) to back that up, but I know what I would put my $$$ on.
    On a side noteÖ
    Shouldnít you be trying to get the stock cats off anyways? They kill performance, I cant even believe how much getting rid of the stock cats helped my performance.

    The intake problem has a lot more merit (and that not saying much). You are altering a tuning device; however. You need to understand how a MAF works to understand why this isnít a huge problem for the ECU to compensate for the change in values.
    A Mass Air Flow sensor is a pretty simple design that heats wire so that them more air flowing into the intake and past the sensor, the cooler the wire will be. From this, you can start to apply it to all kinds of variables and hypothesis how they might affect youíre a/f ratio.
    A CAI will, theoretically generate lower values because more air can cool the heated wire. This is fine and dandy in theory, but often times a very hot engine bay caused by a turbo could heat the wire even more than possible under stock conditions. This causes a extra rich condition in some cases (not very harmful) and a lean condition; if and only if a) the ECU is getting readings out of its range (very unlikely, they are designed to run in the hottest desert and coldest tundra) b) the MAF is getting readings out of its range or c) the MAF sensor is not getting even flow of air and it is giving improper readings (less flow at the top of the intake and more at the bottom.
    The only logical argument is c and I really wouldnít buy it without a flow bench backing that up because if anything it is more even than stock.
    If any loss is noticed it is most likely because of heat soak created by a hot engine bay. Something easily combated by proper heat blocking/removal via heat shields.

    Iím sorry that I had to muck up this post I made about finding these cheap headers by explaining BOV and CAI but as you can see, that attitude is infectious and unfounded.
    I anxiously await your response

    my god that was a precise responce to a much heated debate here on the forum..

  15. #4409
    Registered User
    Join Date
    Jun 2004
    Posts
    4,016
    Quote Originally Posted by BigClunke
    c) the MAF sensor is not getting even flow of air and it is giving improper readings (less flow at the top of the intake and more at the bottom.
    The only logical argument is c and I really wouldnít buy it without a flow bench backing that up because if anything it is more even than stock.

    you hit the nail on the head and that IS the reason why so many hate intakes here. most are crap and are all varying diameters and throw inconsistent reasings from the MAF to the ECU.

    a few CAIS are ok, assuming you are also tuning for them...

    but going from the advice of MANY tuners which i know have a proper background and info to back them up, and hearing you, just speaking hearsay like everyone else..

    i, along with many many others, still go on reputable tuners recommendations and avoid intakes.

    if our stock intake is AOK, then why even bother with a CAI? seems the money could be spent elsewhere on something that will improve the car...not just leave it in te esame state with a little more bling factor. i have also experimented w/ the intake and i am now back at stock.

    same goes for BOVs.

    either way, all thats ****s fine and dandy, but if it isnt helping, and not necessarily hurting..

    whats the point?


    scoobaru--thanks for the info on the headers! has been a good read.

    i think youre just hearing all kinds of things youre just not used to since you went from stock to pretty modded in one fell swoop.
    Last edited by gusto; 11-08-2004 at 03:51 PM.
    Vanitas vanitatum...et omnia vanitas

  16. #4410
    Registered User
    Join Date
    Jan 2004
    Location
    MI
    Posts
    414

    Mythbuster:The BOV

    I feel that this is an issue that seriously needs to be addressed because of the sheer number of useless opinions on the topic.
    Things that are not ok in this post.
    Flaming
    Hearsay
    Blunt ignorance (it is better to have people think you are an idiot, than to open your mouth and remove all doubt)

    A Blow Off Valve (aka bypass valve or show off valve) is an essential part of a turbocharged engine. It relives the excess pressure created by a turbo immediately when opens. The energy created by the turbo cannot be destroyed, so it must be redirected. Without a blow off valve, your engine would continue to rev even when the clutch is depressed. Iím sure you can see why that might be bad thing.
    The stock bypass valve is re-circulating, that means that that pressure is released back into the intake. Now from the KISS (keep it simple stoopid) this is a stupid idea. Your adding in an unnecessary step that only aids in emissions (turbos reuse exhaust gasses, therefore, what is blown off is a mixture of re-circulated gasses and fresh air). I feel that it is most likely reason for Subaru choosing a re-circulating bypass valve is to cut back on emissions.
    Aftermarket BOV's have a variety of designs that range from 100% atmospheric vent to 100% re-circulating vent (like stock) and some are even adjustable.
    These BOV have the same function as the stock bypass valve but you get the "Show Off" noise in between shifts because of the air being forced outside through the valve (often times shaped to accentuate the noise).
    (I expect that many of you already know that, so now it is time for debate...)

    Since some designs do not re-circulate this air; they alter the normal operation of the engine, the potential negative and positive effects need to be weighed before coming to any conclusions about BOV (admittedly they are very few to reach).

    The most common problem addressed with the use of a 100% atmospheric BOV is a "rich condition" in between shifts. Those conditions ruin the catalytic converter and it can smash apart and ruin your turbo

    Rich conditions can be troublesome when your dealing with a catalytic converter because the more rich the condition, the harder the catalytic converter has to work. The harder it has to work, the more energy created. The more energy created the greater the heat created. Etc...
    Catalytic converters are not a frequent maintenance item; meaning they are intended to last the life of the car. They are resilient and designed to take into account a variety of conditions.
    The ideal combustion ratio for gasoline is 14.7:1. For those of you with tuning experience, you know that turbocharged engines are usually around 10:1-11:1 and something that high would cause catastrophic failure. A turbocharged engine creates an enormous amount of heat and to control that heat a rich condition is necessary.

    That means, our engines are already putting more stress on the catalytic converter than any normally aspirated engine would. Clearly, our cats are engineered tough to withstand the harsh conditions that a turbocharger creates.
    When a catalytic converter fails it is usually know by everyone around you, it smells awful and hurts your performance because it is restricted with build up. I really hadnít heard of a cat shattering and flying into the turbo before a fellow board member introduced the concept to me. So I would be interested in hearing first-hand experiences.

    It has been established that a rich condition is created because air that would normally be re-circulated and mixed with fuel, is blown off but the ECUís fuel compensation remains. This does create a rich condition, but you need to consider how little effect that can really have on performance. Our engines are rotating about 600-700 times a minute at idle and much more when you apply throttle. As soon as a revolution is complete the gas leaves the combustion chamber and is expelled or collected and re-circulated (turbocharged). For a few revolutions that rich condition might exist, but will be expelled very quickly. So quickly that a performance increase or decrease would be undetectable and the rich condition would only be momentary.

    The bottom line is an aftermarket BOV cannot ruin your engine unless there is a problem elsewhere. It might wear on your cats a bit more but certainly not enough to justify failure. Any failure attributed to a BOV is a confusion of causation with correlation and should be treated as such, not encouraged by the ďanti-riceĒ members.

    100% atmospheric BOV are a much simpler design than stock. Some aftermarket valves even reverse the valves operation to eliminate to problems with the stock valves ability to hold boost (negligible point unless you have a big aftermarket turbo).
    Conclusions:
    You do not need an aftermarket BOV on even the majority of heavily modified wrxís. They will not help performance. They will not ruin your cat or engine. They will make noise that a lot of clubwrx members donít like.
    Put the money towards something that will help performance, if you got one for free put it on, it wonít hurt.
    This post is my theory of refusal. I am certainly open to hear others well thought out opinions because we really need to stop demonizing these valves, even if you think they are annoying, we have a goal of objectivity. That truly what sets us apart from the ďsports compactĒ scene.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •