"The BIG BOV thread" (Where all bov question threads get merged) - Page 755

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; I am using an analog AutoMeter gauge... might be closer to 18psi... i know it spools really fast compared to ...

  1. #11311
    Registered User Impreza2.0's Avatar
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    I am using an analog AutoMeter gauge... might be closer to 18psi... i know it spools really fast compared to when I first started out, and it's close enough to 20 to feel like an improvement... but based on the math of the td04, 20psi isn't going to last long if it could even muster it. I felt like maxing it out until it burns up the bearing though. It's going to take a failure to justify a replacement with my family... I apologize for just throwing that number out here... yah, more like 18 with luck.

    as for antilag, no, i am not using any form of added-on electronic launch control. I have a manual boost controller, never had a problem with it, it seems pretty snappy. I get boost a lot earlier with it than with the stock BCS.

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  3. #11312
    Moderator Donkey's Avatar
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    Quote Originally Posted by Impreza2.0 View Post
    I am using an analog AutoMeter gauge... might be closer to 18psi... i know it spools really fast compared to when I first started out, and it's close enough to 20 to feel like an improvement... but based on the math of the td04, 20psi isn't going to last long if it could even muster it. I felt like maxing it out until it burns up the bearing though. It's going to take a failure to justify a replacement with my family... I apologize for just throwing that number out here... yah, more like 18 with luck.

    as for antilag, no, i am not using any form of added-on electronic launch control. I have a manual boost controller, never had a problem with it, it seems pretty snappy. I get boost a lot earlier with it than with the stock BCS.
    You are extremely confused. There is no way in hell you are seeing 20psi or even 18 psi by 1200 rpm. And a clipped turbine wheel will spool slower than a non-clipped wheel. Maybe you are seeing faster spool using the MBC over the BCS but not enough to see 18 psi by 1200 rpm. It's 100% physically impossible,no matter what gear you are in. This goes the same for even 2200 rpm. Re-read your original post and think about what kind of information it is projecting................
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  4. #11313
    Pro Manscaper Mikie13's Avatar
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    Wow there is no way you are near 18psi at 1200. Most drivers can barely even get their car moving by 1200rpm in a manual.
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  5. #11314
    Registered User Impreza2.0's Avatar
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    Um, ... yeah... oops... so, 3200rpms ... k?
    I really would not have intentionally inflated my numbers....
    knowing I would probably never have another post taken seriously again.

    I get 18psi 2nd 3rd 4th, 17psi 1st 5th... though I have an MBC and there's a tad of creep to around 18 again in 5th. I hope this sounds a little more normal.

  6. #11315
    Pro Manscaper Mikie13's Avatar
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    Ahhhhh that makes a lot more sense now
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  7. #11316
    Registered User Impreza2.0's Avatar
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    Quote Originally Posted by Mikie13 View Post
    Ahhhhh that makes a lot more sense now
    I think what I was getting at was that only a bpv tunes right for me.
    I've got proof after a considerable number of bovs that they don't work for me.
    Also, on iwsti there's a thread about a warranty denial due to a bov... lol.

    I got the GReddy RZ valve w/RS hard hotpipe and love it. I really don't think about it anymore.
    It is not audible from inside the car at all. It is easy to feel, and my boost needle doesn't jump about like it did on all the others even the oem.

  8. #11317
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    So I gotta question for the BPV using folks - do aftermarket BPVs work in the same way as the stock one?

    Now before someone laughs at the noob question - here's the deal:

    The stock BPV seems to leak somewhat at idle. If you've ever tried to run the stock BPV in a full VTA mode (what? I was curious! Plugged the recirc line of course), you'd realise it leaks/doesn't hold tightly and causes the car to sputter and idle. It's kinda like when slowing down to idle, the BPV still remains partially open/flutters and causes a rough idle. (Proof? When I disconnected the vac line to the BPV while in VTA mode, idle went back to normal. BPV didn't work though!)

    Now take an aftermarket BPV, and try to run it in VTA mode, and it won't do that. It'll stay closed and not "pass" any air....period.


    Why? Is it that an aftermarket BPV (Perrin, Forge, GFB etc) STILL doesn't function as intended?
    Last edited by White GDA; 11-14-2011 at 06:24 AM.

  9. #11318
    Registered User Impreza2.0's Avatar
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    Quote Originally Posted by White GDA View Post
    So I gotta question for the BPV using folks - do aftermarket BPVs work in the same way as the stock one?

    Now before someone laughs at the noob question - here's the deal:

    The stock BPV seems to leak somewhat at idle. If you've ever tried to run the stock BPV in a full VTA mode (what? I was curious! Plugged the recirc line of course), you'd realise it leaks/doesn't hold tightly and causes the car to sputter and idle. It's kinda like when slowing down to idle, the BPV still remains partially open/flutters and causes a rough idle. (Proof? When I disconnected the vac line to the BPV while in VTA mode, idle went back to normal. BPV didn't work though!)

    Now take an aftermarket BPV, and try to run it in VTA mode, and it won't do that. It'll stay closed and not "pass" any air....period.


    Why? Is it that an aftermarket BPV (Perrin, Forge, GFB etc) STILL doesn't function as intended?
    Yes, the aftermarket valve serves the same function as the stock piece.
    Many aftermarket valves use a different mechanism to achieve this.
    There are push sprung and pull sprung types, those without diaphragms, and those with them...
    the variety is endless, and most will create issues in a Subaru unless compensated for.
    The compensation is typically not worth the loss of power or lack of efficiency/reaction speed of the valve.

    The reason the stock valve sits slightly open is due to vacuum force in the system. At idle, there is usually some flutter from that. The reason an aftermarket
    valve is less likely to do this:
    Better machined parts/precision components,
    Being improperly set to hold too much boost or too little,
    The OEM valve may have been "crush modded" and damaged in the process...

    There's actually a lot of reasons why this could happen. It isn't very important... but it's cool to see this was tested, and to hear what resulted... thanks!


    Meanwhile, are you using the stock valve or an aftermarket piece at this point?

  10. #11319
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    Well I'm using an "adjustable" bov at this point (won't call a brand yet before swearing starts). Valve is set to run as a 100% RECIRC of course.

    The stock BPV in question was not "modded" at all, and worked properly before and after. When set to run in VTA mode, the car ran horribly.

    Many aftermarket valves use a different mechanism to achieve this.
    There are push sprung and pull sprung types, those without diaphragms, and those with them...
    the variety is endless, and most will create issues in a Subaru unless compensated for.
    Are you saying that an aftermarket Recirc BPV can also cause issues? Cuz this is what I specifically was asking about. NOT a 100% VTA valve.

    I merely put the recirc valves (stock and aftermarket) into a "pseudo" VTA mode as an experiment, so I could observe/listen to how they acted, as I drove. With them plumbed into the recirc hose, it's really hard to tell when they open IMHO. I do NOT run them that way permanently.

    I should add that when int VTA mode, I noted that the stock BPV held shut just fine under boost (up to 16 psi at the time).
    Last edited by White GDA; 11-14-2011 at 08:06 AM.

  11. #11320
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    I've tried a handful. All of them were not satisfactory except for the one I am using now, a dedicated single-outlet diaphragm type with a hard pipe kit. I had an adjustable one, and it leaked. I don't mean it separated under light vacuum, I mean it was a surge nightmare.

    If you have a valve from a reputable company, don't be ashamed of it. They'll back you up if you back them up, at least that's been my experience.

    There's been a lot of who vs. who for what the best valve is. It is generally agreed however, for those with stock location turbos and TMICs, that a fully recirculating forged billet valve is best. For a totally stock vehicle, the stock valve is inarguably best.

    I personally recommend a GReddy RZ valve with Trust flange adapter and RS Hardpipe Kit. It is pretested to 100psi, so it's safe for sure, and when you order it for a WRX or STi, it comes preset. Mine was stupid simple to install.

    The hardpipe makes the valving audible, more of a flutey whistle that climbs in volume with boost level, but you still have to listen for it. The GReddy is far faster than the stock piece. Otherwise it is as if it were stock.

    So, of course, the obvious question... what valve ARE you using?

  12. #11321
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    Quote Originally Posted by Impreza2.0 View Post
    I've tried a handful. All of them were not satisfactory except for the one I am using now, a dedicated single-outlet diaphragm type with a hard pipe kit. I had an adjustable one, and it leaked. I don't mean it separated under light vacuum, I mean it was a surge nightmare.

    If you have a valve from a reputable company, don't be ashamed of it. They'll back you up if you back them up, at least that's been my experience.

    There's been a lot of who vs. who for what the best valve is. It is generally agreed however, for those with stock location turbos and TMICs, that a fully recirculating forged billet valve is best. For a totally stock vehicle, the stock valve is inarguably best.

    I personally recommend a GReddy RZ valve with Trust flange adapter and RS Hardpipe Kit. It is pretested to 100psi, so it's safe for sure, and when you order it for a WRX or STi, it comes preset. Mine was stupid simple to install.

    The hardpipe makes the valving audible, more of a flutey whistle that climbs in volume with boost level, but you still have to listen for it. The GReddy is far faster than the stock piece. Otherwise it is as if it were stock.

    So, of course, the obvious question... what valve ARE you using?
    Ha. Right now I'm using the GFB Respons. Set to fully recirc. It actually is more audible than the stocker unit...and I have not removed the intake silencer thing. Like with your RZ, you have to listen for it though.

    I guess the benefit for me is that I can switch to VTA if I get bored / for jollies, then switch back to normal once my ricer glands have drained (i.e. for a day or so).

    I've had good experiences with the Forge VTA BOV as well. HKS SSQV, thought that sounded kinda odd....and I did get some surge at lower boost.

    Ironically, for the couple of hours that I ran the stock BPV in VTA form, that was THE LOUDEST of all!

  13. #11322
    Registered User Impreza2.0's Avatar
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    The GFB has a very small overall diameter in the inlet and outlet... something to consider. It is a very solid valve and has no known issues with Subaru applications.
    HKS is known for problems with Subarus. Nissans and Toyotas seem to do OK when set up right, but overall, GFB is a better valve insofar as quality control and customer relations.

    GFB makes good quality products, and stand behind them. HKS does also make a good product, but much larger quantity, so odds of a fail are slighter going your route.

    Occasional "for fun" VTA stresses components unnecessarily. Keep it a BPV or swap for a really TOL dedicated BPV.

  14. #11323
    Registered User Turb0Licious's Avatar
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    If you run a GFB BPV Respons (or any reliable BPV) will you hear it more with an aftermarket CAI as apposed to stock? I ask this because I had a Forge 007 DV on my old GLI and could hardly hear it but when I dropped in a CAI I heard it a lot.

    Also, I know you will hear the GFB Respons the more you adjust it to VTA, but at 50/50 or fully recirc with a CAI will you hear it more as apposed to without an aftermarket CAI?

    Basically I'm curious If a CAI increases the sound of an aftermarket BPV as it does with a DV, Thanks.
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  15. #11324
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    It will. Or even more so with an SRI or just a snorkus delete to the airbox (which you can't do with your generation WRX from what I understand).

    That's why we always suggest if you really want the sound, you're better off getting an Intake and tuning for it.
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  16. #11325
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    im glad i got on the forum and have been reading all these post lol i really wanted a bov but.... after reading and learning about them yea must agree no reason for them unless u want the sound which...honestly all i wanted lol but the sound isnt worth messing up my new wrx lol

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