To BOV or not to BOV, that is partially the question. - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-15-2008, 04:29 PM   #1
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Default To BOV or not to BOV, that is partially the question.

So this is the miata:
http://www.cardomain.com/ride/2088066/

I've had it for 7 years now, and it's time to boost it. Currently running 119.6HP at the wheels, and a factory new motor with 30,000 miles on it. I work at a performance shop and will be custom fabbing basically everything. I've amassed most of the pieces, but just looking for a bit of feedback on the setup:

Turbo: Rebuilt T28 from a SR20DET, internal wastegate
Manifold & Downpipe custom
Lindsay Racing 6" Thermal Hard Pipe Air / Water intercooler
Custom coolant reservoir
Oil / Coolant cooler for coolant
AEM F/IC

Now I'm sort of stuck on the question of a BOV. If I go for one, I will go recirc, but I'm also planning on running only about 8 psi on this setup. I've read a fair amount on the internets about not needing a BOV, and many proponents of this stance point out to factory cars that are running higher levels of boost without BOV's. Another common example are Subaru owners, who are running aftermarket turbo's at over 20PSI without a bov. SO, I'm looking for peoples opinions on this matter. I'd rather not have a BOV simply to save a bit of money, and I don't think they look terribly good (yah i know, shut up ).

Thanks folks.
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Old 04-15-2008, 04:38 PM   #2
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Quote:
Originally Posted by dustinb View Post
So this is the miata:
http://www.cardomain.com/ride/2088066/

I've had it for 7 years now, and it's time to boost it. Currently running 119.6HP at the wheels, and a factory new motor with 30,000 miles on it. I work at a performance shop and will be custom fabbing basically everything. I've amassed most of the pieces, but just looking for a bit of feedback on the setup:

Turbo: Rebuilt T28 from a SR20DET, internal wastegate
Manifold & Downpipe custom
Lindsay Racing 6" Thermal Hard Pipe Air / Water intercooler
Custom coolant reservoir
Oil / Coolant cooler for coolant
AEM F/IC

Now I'm sort of stuck on the question of a BOV. If I go for one, I will go recirc, but I'm also planning on running only about 8 psi on this setup. I've read a fair amount on the internets about not needing a BOV, and many proponents of this stance point out to factory cars that are running higher levels of boost without BOV's. Another common example are Subaru owners, who are running aftermarket turbo's at over 20PSI without a bov. SO, I'm looking for peoples opinions on this matter. I'd rather not have a BOV simply to save a bit of money, and I don't think they look terribly good (yah i know, shut up ).

Thanks folks.
Don't most of those factory setups without bovs... run a recirc or bypass valve?

Compressor surge isn't good, I'm personally pro BOV. If I could not use one I would... but its there for a practical reason.
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Old 04-15-2008, 04:44 PM   #3
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I'd love to see a list of the benefits of not running a BOV / bypass valve. And "because it's cheaper" doesn't count.

C
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Old 04-15-2008, 04:49 PM   #4
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Pros
*don't have to **** up your already barely sealed charge pipes
*listen to your music in peace
Cons
*your motor makes turkey calls
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Old 04-15-2008, 04:56 PM   #5
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Quote:
Originally Posted by mazda/nissan View Post
Pros
*don't have to **** up your already barely sealed charge pipes
*listen to your music in peace
Cons
*your motor makes turkey calls
#1 - I'll assume you're kidding.
#2 - recirculated bov / bpv's don't add any noise.
#3 - Some people like turkey's.

C
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Old 04-15-2008, 04:58 PM   #6
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Quote:
Originally Posted by chriscar View Post
#1 - I'll assume you're kidding.
#2 - recirculated bov / bpv's don't add any noise.
#3 - Some people like turkey's.

C
yeah i was kidding, but some recirc'd systems are actually quite loud. They won't have a whistleling effect but they are still very noticable as a pressure release valve
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Old 04-15-2008, 05:00 PM   #7
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Non-bov

Pros:
Simplicity (come on, its 1 vac line and 1 device)
Cost (ebay bovs work great)

Cons:
Compressor surge (gobble gobble)
compressur surge leads to short turbo life (debated of course)
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Old 04-15-2008, 05:03 PM   #8
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Quote:
Originally Posted by Splitime View Post
Non-bov

Pros:
Simplicity (come on, its 1 vac line and 1 device)
Cost (ebay bovs work great)

Cons:
Compressor surge (gobble gobble)
compressur surge leads to short turbo life (debated of course)
You broke the rule. Because it's cheaper is not a good reason. And I'm all about simplicity, but when it's at the cost of functionality, simplicity looses.

C
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Old 04-15-2008, 05:06 PM   #9
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I originally installed my system with no BOV since I was only running 7 psi. But, I really grew to hate the compressor surge noise and decided to put a BOV in anyway even though I did not 'need' it. Much, much better. I would do it again in a minute.

IMO calling the surge sound a turkey gobble is being generous. It sounds more like a low frequency fart to me and sounds like crap to me, literally. See the BOV link in my sig for more info.
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Old 04-15-2008, 05:13 PM   #10
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Compressor surge will also hurt spool up between shifts. And it sounds goofy as hell.

Be like all the cool kids and get one.
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Old 04-15-2008, 05:25 PM   #11
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This is really a thread? BOVs are like 20 bucks and don't even have to make a noise. I think I spent more on my washers.
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Old 04-15-2008, 05:26 PM   #12
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We had a kid at work who was so proud of his rebuilt T3 for his honda. NO BOV was used, 600 miles later the turbo ate the nut...
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Old 04-15-2008, 07:02 PM   #13
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Do any of you have idle issues using a VTA BOV?

I'm really just asking about the BOV because quite a large following of our customers are suddenly anti BOV. One of them is a guy building up a 91 skyline RB26. He's going single turbo GT4088R turbo, Full Race manifold, Haltech standalone. He was originally going to have a BOV, but has now decided to screw the BOV and run without it. His cohert in this processes is building a 7M-GTE up with a big turbo and has also decided to screw the BOV. The BOV definitely makes sense to me.
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Old 04-15-2008, 07:14 PM   #14
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Nope
Disclaimer - I am using the MAP, not MAF
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Old 04-16-2008, 01:09 AM   #15
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actually with almost any after market ecu/piggyback VTA BOV's can be used i suspect. I think greddy blues have antistall and greddy ultimates can delete the MAF, so its not that big of a hurdle really anymore
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Old 04-16-2008, 02:33 AM   #16
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Quote:
Originally Posted by dustinb View Post
Do any of you have idle issues using a VTA BOV?

I'm really just asking about the BOV because quite a large following of our customers are suddenly anti BOV. One of them is a guy building up a 91 skyline RB26. He's going single turbo GT4088R turbo, Full Race manifold, Haltech standalone. He was originally going to have a BOV, but has now decided to screw the BOV and run without it. His cohert in this processes is building a 7M-GTE up with a big turbo and has also decided to screw the BOV. The BOV definitely makes sense to me.
So, your customer is going to spend the skrill to swap out the RB20DET for an RB26DET just to anally rape his turbo? Wow, he should just give the money he'll spend on that project to someone else, li ke me.

I have a factory turbocharged mass air car which had installed a cheap plastic compressor bypass valve.. Never would boost a steady 16psi like it was supposed to, until I swapped out the BOV for a cheap ebay SSQV running VTA. After that swap, the car boosts full solid 16psi w/out leaking but of course since its setup for VTA the car runs odd. Since I've swapped that knockoff out for a Greddy Type-S knockoff running recirc.

Using a VTA BOV on a mass air car has no advantage at all unless you want to hear the valve.. What you're doing is releasing to the atmosphere metered air, which will cause the car to run rich after the air is released. Spoolup between shifts is significantly slower, the back bumper gets black faster, and the car will backfire between shifts often. Eventually the computer will likely trigger the check engine light for abnormal mixture conditions.

FWIW my Mazdaspeed miata with a VTA BOV would die at idle often.

If you want simple, BOV. If you want proper, BPV. Thats just my opinion.
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