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Thread: Forge BOV query

  1. #1

    Default Forge BOV query

    Hey guys I recently got my car tuned with a few upgrades, one of which is the Forge type RS BOV:

    Forge Motorsport | Alloy Fabrication

    I was under the impression that it would be plumb back and I would not hear the BOV venting, however it still does. Does anyone know if it's possible to adjust it so that it doesn't vent?

  2. #2
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    Quote Originally Posted by Chu View Post
    Hey guys I recently got my car tuned with a few upgrades, one of which is the Forge type RS BOV:

    Forge Motorsport | Alloy Fabrication

    I was under the impression that it would be plumb back and I would not hear the BOV venting, however it still does. Does anyone know if it's possible to adjust it so that it doesn't vent?
    Do you have an intake?
    If so, that's why you can hear it
    Newbie FAQ My Build Thread
    From stock, to GT3071, to substantially less modded, many lessons learned!
    3" HTP | 100 Cel DP | Autotech HPFP | AP V3 - Self Tuned on E20 | JBR RSB | CPE S2 REM | JBR Shifter Bushings

  3. #3

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    You can plug it so it won't vent. That way, you won't hear a thing...except your turbo eating itself! The link you gave says it is adjustable, so if it's fluttering or something you can tune that out, but it won't be silent. If you want quiet, why not just stick with oem?

  4. #4

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    Quote Originally Posted by Lachlan View Post
    You can plug it so it won't vent. That way, you won't hear a thing...except your turbo eating itself! The link you gave says it is adjustable, so if it's fluttering or something you can tune that out, but it won't be silent. If you want quiet, why not just stick with oem?
    Yeah I didn't think it was possible to completely have it plumbed back into the intake and be silent. From what I've heard/read the OEM plastic BOV doesn't hold boost well so I had it upgraded to a metal one.

  5. #5
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    Quote Originally Posted by Chu View Post
    Yeah I didn't think it was possible to completely have it plumbed back into the intake and be silent. From what I've heard/read the OEM plastic BOV doesn't hold boost well so I had it upgraded to a metal one.
    It's fine for up to 20psi...
    Newbie FAQ My Build Thread
    From stock, to GT3071, to substantially less modded, many lessons learned!
    3" HTP | 100 Cel DP | Autotech HPFP | AP V3 - Self Tuned on E20 | JBR RSB | CPE S2 REM | JBR Shifter Bushings

  6. #6

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    Yeah, oem is good for almost anything the k04 can put out (see that nipple on the top? That's boost pressure holding it shut). Like sarcastic asked, do you have an intake? If so, you will hear any valve more. If it's an early model forge, they were known for sounding like movie sword clangs. Lol

  7. #7

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    I wasn't aware of what boost the stock BOV was good to but oh well it's too late now, thanks for letting me know.

    Yeah I've got a SRI and yep it sounds something like that haha, a high pitched metallic noise. Considering changing it to something else later on.

  8. #8
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    Quote Originally Posted by Chu View Post
    I wasn't aware of what boost the stock BOV was good to but oh well it's too late now, thanks for letting me know.

    Yeah I've got a SRI and yep it sounds something like that haha, a high pitched metallic noise. Considering changing it to something else later on.
    Yeah, with an Sri you're going to hear the bpv... I can hear mine quite easily!
    If you don't want the noise, the only thing you can really do is put stock air box back on...
    Newbie FAQ My Build Thread
    From stock, to GT3071, to substantially less modded, many lessons learned!
    3" HTP | 100 Cel DP | Autotech HPFP | AP V3 - Self Tuned on E20 | JBR RSB | CPE S2 REM | JBR Shifter Bushings

  9. #9

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    Or go bigger intake

  10. #10

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    Yeah it is quite loud but I can live with it, I just prefer my car to be a bit more discreet to not attract unwanted attention .

  11. #11

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    Hey I have ordered one of these too. What spring setting and shims are you using on your setup?? You sound like your running standard boost levels tho... I am on 21psi, so probably different. I would like the clang noise!

  12. #12

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    Someone correct me if I'm wrong but the bov that I've got is different to yours. As far as I know I can't change out springs/shims in mine, I've got a dial on the top of mine to adjust the pressure of the valve.

  13. #13

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    Ah I have the Forge V1 with a swapable springs. Makes the flutter flutter ching noise on boost and kaping! on WOT! Love it.

  14. Default

    If it's fluttering (fully sick sound) on throttle lift off or gear change then the valve is too stiffly sprung

  15. #15

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    Quote Originally Posted by allo80 View Post
    If it's fluttering (fully sick sound) on throttle lift off or gear change then the valve is too stiffly sprung
    I read a great article that says with the Forge that valve flutter is perfectly normal for this type of BPV with part throttle. IF it is fluttering on full boost that is most likely compressor surge. When I give it WOT in any gear it gives a nice suck and then PING! with zero flutter.


    Oh hear I dug it up

    "Each user will need to adjust their valve so that it will hold boost all the way to the
    specified redline of their application under wide open throttle without experiencing
    any valve fluttering at full-boost throttle lift.
    If valve fluttering is felt at full-boost throttle lift, this is typically an indication that
    the valve is adjusted too stiffly.
    If the valve is leaking under wide open throttle before the specified redline of the
    application is reached, this is typically an indication that the valve is adjusted too
    softly.
    Please note that valve flutter under partial throttle conditions or partial boost throttle
    lift is a normal occurrence as IS NOT an indication of compressor surging. Partial
    throttle or partial boost valve flutter is solely an indication that the valve is
    responding to an inconsistent pressure differential on either side of the throttle body
    as it is being modulated. Compressor surging would only be experienced if full-boost
    throttle lift valve flutter is experienced and is not corrected immediately."

    "
    The flutter is something you will experiance on the piston style BOV iT's valve flutter. This is what happens when the valve opens and closes very rapidly as the pressure in the bottom side and the top side get very close to equal. Mine does it between shifts under light loads. I have the turbo xs bov. the higher spring rate will eliminate some of it but You will have a less responsive bov."

    Not sure where this came from, but I have seen it a few times quoted with no rebuttal. I discussed this with my tuner and he also said it was fine. Zero feeling of surge from turbo, just smooth gear changing all round.


    On a side note....holy shit this BPV is far louder than stock. IT scares the crap out of people who are on the street or windows down. I frequently "PING" next to cars and they back off throttle thinking something is going wrong haha. I call part throttle boosting "Hitting the jackpot" as it goes butta chiiinggg" like its rainin gold lol
    Last edited by nas711; 12-04-2015 at 09:55 PM.
    2010 Gen 2 - "SPOOOL" (VIC) - Fully bolted

    CORKSPORT TURBO | COBB AP3 | COBB DOWNPIPE | COBB REM | AUTOTECH HPFP | CORK SPORT 3" PS MAF INTAKE | COBB SF AB | CPE TMIC | CPE HEADERS | COBB 3 PORT EBCS | 3 BAR MAP| PEDDERS COILOVERS | DBA T4 SLOTTED ROTORS | CORKSPORT EYELIDS| FORGE V1 BPV| | MAGNAFLOW CUSTOM | VELOCITY RED | PEARL 2PAC STOCK RIMS | DUAL TUNED BY HPF ON E30

  16. #16

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    Found some more info on piston based bpv's and valve flutter.

    Valve Fluttering:

    Valve fluttering is commonly thought to be an automatic indicator of compressor surging, and I would like to put that rumor to rest right now. This could not be further from the truth.

    Compressor surging (caused by a bypass valve) implies that the bypass valve is not opening fully to allow the optimal amount of airflow required to keep the compressor wheel of the turbo spinning at an optimal speed.

    Bypass valve fluttering will occur under various circumstances, so please consider under what situations you are experiencing fluttering before you presume that compressor surging is taking place, or more importantly, before it is assumed that a problem even exists.

    Valve fluttering under wide open throttle or full boost throttle lift, again, typically means that a valve is tuned or adjusted to stiffly, and while this can lead to compressor surging and potential damage over an extended period of time, if the user fixes the issue quickly, no significant damage will occur. It would only be after prolonged use of a valve in an improperly tuned configuration that compressor surging MAY lead to damage or excessive wear on the turbocharger.

    Valve fluttering under partial throttle or partial boost throttle lift, on the other hand, is a completely normal occurrence and IS NOT an indication of compressor surging by any measure.

    Partial throttle or partial boost valve fluttering is solely an indication that the valve is directly responding to the inconsistent pressure differential on either side of the throttle plate (throttle body).

    An internal combustion engine naturally creates a vacuum effect during the intake stroke of a given cylinder. When boost pressure is built from the turbocharger, it will reach a certain level inside the intercooler piping, but as it enters the intake manifold, it is almost instantly reduced by a given amount of vacuum created by the intake stroke of the engine, thus resulting in a marginally lesser amount of boost pressure inside the intake manifold compared to inside the intercooler piping.

    Since the bypass valve sees references from both of these pressure sources, the sealing surface of the valve, be it a diaphragm or a piston, will respond to these differences in pressure, as minor or severe as they may be. This sealing surface response is what is creating the fluttering effect at partial throttle or partial boost throttle lift.

    Exact situation mine is in. Nice even flutter when part throttle with a little ping and under fully load nice sucking noise and then massive kaping with no flutter what so ever. Boost spikes a bit though..but nothing over a psi.
    2010 Gen 2 - "SPOOOL" (VIC) - Fully bolted

    CORKSPORT TURBO | COBB AP3 | COBB DOWNPIPE | COBB REM | AUTOTECH HPFP | CORK SPORT 3" PS MAF INTAKE | COBB SF AB | CPE TMIC | CPE HEADERS | COBB 3 PORT EBCS | 3 BAR MAP| PEDDERS COILOVERS | DBA T4 SLOTTED ROTORS | CORKSPORT EYELIDS| FORGE V1 BPV| | MAGNAFLOW CUSTOM | VELOCITY RED | PEARL 2PAC STOCK RIMS | DUAL TUNED BY HPF ON E30

  17. #17

    Default

    Here is what my car sounds like (not my car, but a nice example of valve flutter. Listen how when he builds up boost in the low revs it does a flutter ping, but upon WOT it give no flutter but a nice strong ping. This is not surge. He is running stock with yellow spring (weak) and I am running with added boost with blue spring and a shim. True surge is a slow wub wub wub sound (even flutter dump if it ends up venting). Valve flutter is much quicker as heard here and is safe. I hope this helps those with a valve style BPV to stop freaking out.

    https://www.youtube.com/watch?v=LlCEDZ51RGs
    Last edited by nas711; 10-05-2015 at 11:30 AM.
    2010 Gen 2 - "SPOOOL" (VIC) - Fully bolted

    CORKSPORT TURBO | COBB AP3 | COBB DOWNPIPE | COBB REM | AUTOTECH HPFP | CORK SPORT 3" PS MAF INTAKE | COBB SF AB | CPE TMIC | CPE HEADERS | COBB 3 PORT EBCS | 3 BAR MAP| PEDDERS COILOVERS | DBA T4 SLOTTED ROTORS | CORKSPORT EYELIDS| FORGE V1 BPV| | MAGNAFLOW CUSTOM | VELOCITY RED | PEARL 2PAC STOCK RIMS | DUAL TUNED BY HPF ON E30

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