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-   -   Technical info on BOV/BPV Set up and operation (https://legacygt.com/forums/showthread.php?t=150687)

m sprank 12-22-2010 01:44 AM

Quote:

Originally Posted by aekOne (Post 3210310)
haha are you australian mate?? i see you mention a VL turbo in the spiel above but i know they are an Australia only car?

No, the info comes from GFB Pete. he is Australian as GFB is an Australian company.


Quote:

Originally Posted by doccrowley
so, what has been diagnosed in my car as a wastegate flutter might actually be BPV flutter?

Stock BPV and stock wastegate in my Perrin TMIC, Gimmick afta maf and inlet tube, CoBB lite pulley, COBB UP, CNT catted DP to X02 exhaust, K&N panel filter all on stock VF-40. 19psi tune.

** By the way, ran zero re-circ for a week on my 5EAT and it was an utter disaster at anything other than full throttle. So much stutter it was crazy at partial throttle and a huge jerking motion when letting off the throttle. That's what I get for destroying the re-circ hose when I installed the new turbo inlet tube.**

Summary: do I need an AVO 15psi solid boost actuator to solve current stutter or an upgraded BPV? Or both?

Thanks.

Well, 19psi is high for a VF-40. Honestly. You are right on the edge of that turbo.

Stock BPV should only be run 100% recirc. Stock BPV should hold your boost and work for your app. But it could be giving out too.

Upgraded wastegate actuator might also help. Not sure. It is easier if I saw the car myself, or at least some data.

aekOne 12-22-2010 07:22 AM

Quote:

Originally Posted by m sprank (Post 3210488)
No, the info comes from GFB Pete.

Ah i see.

Quote:

Originally Posted by m sprank (Post 3210488)
GFB is an Australian company.

It sure is :)

SubaruFanatic 12-28-2010 04:55 PM

so what i'm getting from this thread is that a GFB bov will solve my problems, because other than that I am not sure how else to get rid of the surge. I really dont need my turbo blowing up from surge and its bad even at any boost. I thought my 300 dollar BOV would have been good but i guess not compared to GFB.

m sprank 12-28-2010 05:32 PM

No. Take out the GFB and just insert "your brand here". The SSQ works slightly differently, but principle is the same.

Like I said in my original post, there is propaganda here. But plenty of great info too. Look past the propaganda and take in the data and instructions.

jfg22557 12-28-2010 11:53 PM

glad to see this info all organized in one thread sprank.

should be stickied for sure.

m sprank 12-29-2010 12:20 AM

I keep having to bump it so people can find it. I get asked all the time about BOV set ups.

Maybe I posted it in the wrong forum?

I dont ask for stickies. I am proud to already own one. But a second would be sweet, LOL.

SubaruFanatic 12-29-2010 09:39 AM

Quote:

Originally Posted by m sprank (Post 3216308)
No. Take out the GFB and just insert "your brand here". The SSQ works slightly differently, but principle is the same.

Like I said in my original post, there is propaganda here. But plenty of great info too. Look past the propaganda and take in the data and instructions.

ok so it seems to me like the pressure from the turbo is there but the volume is not there... so would that mean the vf40 isn't big enough for this set up? Also I am going to recirculate my BOV and see if that helps.

m sprank 12-29-2010 10:37 AM

What set up do you have? Sorry if you already posted. If you have a FMIC, chances are teh VF-40 is struggling. You could try a smaller restrictor pill (if not using an EBCS). Maybe a 0.8 even. It will make the turbo work harder, but could get you the charge air you need.

We have seen VF-40's have issues with the pressure drop from FMIC's. It takes a lot of work to get the boost back after sometimes. The VF-40 is undersized for most FMIC applications (IMHO).

SubaruFanatic 12-29-2010 07:33 PM

yes i have a tru boost and i'm trying to dial it in but yeah it seems like this turbo doesn't like the fmic very much which i was aware of and planning on putting a bigger turbo on anyway. It makes good power for stock turbo

jfg22557 12-29-2010 09:54 PM

Quote:

Originally Posted by SubaruFanatic (Post 3217834)
It makes good power for stock turbo

decent spool maybe.. thats about all the vf40 has going for it when pushed. and thats not even really much to talk about.

m sprank 12-29-2010 10:24 PM

Its the turbo not liking the FMIC. VF-40/46 are really pathetic when it comes down to it.

SubaruFanatic 12-30-2010 05:05 AM

Quote:

Originally Posted by jfg22557 (Post 3218016)
decent spool maybe.. thats about all the vf40 has going for it when pushed. and thats not even really much to talk about.

Quote:

Originally Posted by m sprank (Post 3218042)
Its the turbo not liking the FMIC. VF-40/46 are really pathetic when it comes down to it.

yes i agree that it does not like high boost pressure i am only running 15-17psi i use to push it past 19 but I see no need for it since it doesn't make much of a difference after about 17psi. also I want to keep from killing it :lol:

m sprank 12-30-2010 09:21 AM

20 is possible. but anything over 18.5 is killing it fast. Asking it to hit 18 with the FMIC might require a restrictor pill and a EBCS. Maybe as small as a 0.8mm pill. Which will certainly degrade turbo life.

If you can get it to hit and hold 17-17.5psi with a FMIC you are fine. That is about all the VF-40/46 can do.

SBT 12-30-2010 10:20 AM

Mike - Good info. Stickied this one too. ;)

SubaruFanatic 12-30-2010 04:36 PM

Quote:

Originally Posted by m sprank (Post 3218426)
20 is possible. but anything over 18.5 is killing it fast. Asking it to hit 18 with the FMIC might require a restrictor pill and a EBCS. Maybe as small as a 0.8mm pill. Which will certainly degrade turbo life.

If you can get it to hit and hold 17-17.5psi with a FMIC you are fine. That is about all the VF-40/46 can do.

ok i just recirculated my bov and switched my intake back to the stock and didn't make much of a difference besides not back-firing when i shift. I took it for a test drive and funny thing is if i give it 3/4 throttle it will hit around 19-20 and bounce back and forth but if I give it full throttle it will hold at about 15 then taper off to about 13psi.??? I have always had a problem with this turbo dropping around 13psi but why would it be different when I have it half throttle or full throttle.


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