Blow Off Valve FAQ: Read if you are thinking of buying one!

[IHaveADream]

Simply brilliant. Great resource. Thanks so much!

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[Jaymansomething]

In for later read

[sleazy07sti]

Hey bro quick question.I'm currently running a tial 50mm bov that is not welded to my fmic pipe.it is held on with a tmic flange thay bolts to a fmic flange ,two clamps and a silicone tube between them.I purchased it from a nasioc member who from what I Belive had a 14psi spring and I was getting nothing but surge.everyone told me that this is how it was suppose to should so I drove on it for 2-3mnths.so today I purchase a 11psi(pink) spring as I'm running -17 to -21 in vac at idel but I'm still getting the surge.could this be because it is not welded to my pipe and I'm leaking like crazy or should a try a 10 or 12 psi spring?

[DaveC113]

Originally Posted by boost-o-matic

In light of the fact that it sounds as though the part has changed for the '08+ WRX's, here's my ?

I have a 2010 WRX and am being told that the OEM BPV or BOV(whatever your preference) leaks at around 17-18 psi. Is this true? Looking to get my car custom tuned soon and want to know if I need to upgrade this part or not prior to tuning. Also need to determine if running the OEM intercooler on my 2010 is going to be okay at 18-19psi. Hearing stuff about the plastic endtanks not withstanding boost much beyond 18psi. I don't ever plan on running high boost(race fuel), but do want to have a 93 octane map made which will wiststand an additional psi over 91 octane. I will be daily driving on 91. Don't really want to spend another $850 upgrading the BOV and i/c as I'm planning to keep the stock turbo, but just add things like EL headers, up-pipe, intake and EBCS to compliment my TBE and AP.

Anyone pressure tested the OEM BOV in the '08+ to see where it starts leaking? Did this on the eclipse I used to have and the OEM unit held to 23 psi. I gave a way my turbo pressure tester with the last car when i sold it. Guess I could always make another one.

I have exactly the same question, same car, same mods... don't want to waste $175 on a new bpv if I don't have to... anyone?

[twinturbomeow]

nvm11

[Nathan_troy1983]

Great post, I am so glad that I am reading before buying any of these parts.

[eXploited_GR]

Need some help..

I have a 2008 STI and my By-Pass valve has a crack in the elbow where the hose connects... and I need to get a new one ASAP.. But I cannot find one in stock anywhere...

What are my options as to what will fit? Any WRX BPV??

[jay25RS]

Originally Posted by eXploited_GR

Need some help..

I have a 2008 STI and my By-Pass valve has a crack in the elbow where the hose connects... and I need to get a new one ASAP.. But I cannot find one in stock anywhere...

What are my options as to what will fit? Any WRX BPV??

So the elbow is cracked and not the bov? Just get a WRX one (pre 2008) and it'll bolt to your bpv.

[Meech3k]

Thanks for all the FAQs. I read a couple of your threads already, answering my questions and ones I wouldn't think of. Good ****!

[cjkarling]

Have the OEM BPVs changed over the years? Yes. 08+ Subarus have a BPV that is plastic. So if you for some reason you have a plastic BPV, it will not hold as much boost as the old metal ones. The plastic ones will only hold ~17PSI give or take.

I have a 2012 WRX stage 2 pumping out 19.5 PSI. Is my plastic BPV leaking?

[WRB19]

Originally Posted by cjkarling

I have a 2012 WRX stage 2 pumping out 19.5 PSI. Is my plastic BPV leaking?

no .

[cjkarling]

How can you tell if it is?

BTW; This is my second WRX, I have a 2003 Bugeye that was stage one, I knew a lot of this stuff, but I have been out of the game for about 8 years.

[Fail Puff]

Originally Posted by Unabomber

No. You need to read the post again. BPV/BOV that 100% recirculates = 100% fine. Anything else = rich.

sorry but i am confuse.. so if i get this then i wont be running rich? http://www.importimageracing.com/for...7-wrx-sti.html coz it said its 100% venting D:

[the suicidal eggroll]

Originally Posted by Fail Puff

sorry but i am confuse.. so if i get this then i wont be running rich? http://www.importimageracing.com/for...7-wrx-sti.html

Does it recirculate? No, therefore it is not fine to run, and will make the car run rich.

[Fail Puff]

so..all BOV will run rich then D:

[Fail Puff]

Originally Posted by the suicidal eggroll

Does it recirculate? No, therefore it is not fine to run, and will make the car run rich.

what if i get it tune?

[the suicidal eggroll]

Originally Posted by Fail Puff

so..all BOV will run rich then D:

Yes

Originally Posted by Fail Puff

what if i get it tune?

You can't tune for an atmospheric BOV

[Fail Puff]

ohhh ok but regular ones i can yeah?

[brett192]

If it's an aftermarket BOV that recircs 100% back into the intake, it'll be essentially the same as the stock BPV tuning wise.

[Fail Puff]

so its tuneable! D: lol well if its pretty much the samething as BPV then its good!?

[the suicidal eggroll]

Originally Posted by Fail Puff

ohhh ok but regular ones i can yeah?

What? I think you need to go back and read a bit. Start here:
http://forums.nasioc.com/forums/show....php?t=2339839

If by "regular ones" you mean recirculating bypass valves (BPV), then there is nothing to tune for, because they work exactly like stock.

[the suicidal eggroll]

Originally Posted by Fail Puff

so its tuneable! D: lol well if its pretty much the samething as BPV then its good!?

What on earth are you going on about?

[sc00by4life]

Originally Posted by Fail Puff

so its tuneable! D: lol well if its pretty much the samething as BPV then its good!?

No....you can't. People are confusing a BOV with a BPV.

You cannot tune for an atmospheric BOV.

[rocketperson7]

unless it's speed density
:stirpot:

[tjmmason93]

Originally Posted by the suicidal eggroll

Yes

You can't tune for an atmospheric BOV

Why isn't it tuneable ? I was always under the impression you can drop the fuel tables to control the amount of fuel and air pumped in through the car to safely get away from the half second rich moment after spool ?