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2 Blowoff Valves-Pros & Cons

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Old 06-01-07, 10:30 PM
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CantSeeMe
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Default 2 Blowoff Valves-Pros & Cons

Im curious to find out others thoughts on this:
I currently have a Blitz BOV on my Na-T setup already. But i also happen to have a 2nd Blitz BOV that i had basically bought for the pipe it came with.
I was planning to just sell the 1 i didnt use . But im wondering what benifit (if any ) I would get from adding it to my setup as well?
Perhaps 1 on the hotside, and 1 on the cold?
I know its not necessary for my setup, But can anyone tell me what scenario typically would call for having 2 BOVs?..... Im assuming a higher HP application?

**Edit: Mods I apologize, can you please move this to the SC performance area **

Last edited by CantSeeMe; 06-01-07 at 10:35 PM. Reason: Im sorry wrong forum
Old 06-02-07, 02:01 AM
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DryBlaze
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When 1 bov isnt enough (turbo surge) then use 2 or get a differnt one. It would help out the car on higher boost (not really any gain on low boost) and will sacrafice sound (quiter).
Old 06-03-07, 09:55 AM
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Moved for ya.
Old 06-03-07, 10:09 AM
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mitsuguy
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yah, unless you are running an extremely large turbo, there is no need for two BOV's...

even then, you are better off with one large bov (greddy Type-R, tial 50mm, etc)
Old 06-03-07, 11:20 AM
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1sxyrxy
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one BOV can only handle a certain amount of BOOSt. like the hks one only handles like around 30psi. so once you start pushing id say over 25 then you will need 2
Old 06-03-07, 11:26 AM
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mitsuguy
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Originally Posted by 1sxyrxy
one BOV can only handle a certain amount of BOOSt. like the hks one only handles like around 30psi. so once you start pushing id say over 25 then you will need 2
it has nothing to do with boost pressure... it has to do with volume of air.... on a smallish engine, a small turbo can give lots of boost, 30 psi or better even, and still not need 2 BOV's... it's when you are flowing serious air volume that you would need a larger or secondary bov...

boost pressure ability has to do with the internal construction, spring rate and such of the bov itself...

here's an example - 30 psi boost, big turbo, 4 cylinder - one normal bov would be ok... 30 psi boost, big turbo, 8 cylinder - either two bov's, or a large single unit...
Old 06-03-07, 01:30 PM
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Originally Posted by mitsuguy
it has nothing to do with boost pressure... it has to do with volume of air.... on a smallish engine, a small turbo can give lots of boost, 30 psi or better even, and still not need 2 BOV's... it's when you are flowing serious air volume that you would need a larger or secondary bov...

boost pressure ability has to do with the internal construction, spring rate and such of the bov itself...

here's an example - 30 psi boost, big turbo, 4 cylinder - one normal bov would be ok... 30 psi boost, big turbo, 8 cylinder - either two bov's, or a large single unit...

+1 ^^ i couldnt have said it any better.
Old 06-03-07, 08:02 PM
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Hey Bill. Remember my old roomate's 1000hp Supra? His has two blow off valves. He runs that thing at high boost. He has one right before the inlet on the intercooler and the other one right after the outlet allowing you to see them through the side air damn on the front bumper. They sound nice and look good but I think they would be most useful when you are running a car with alot of boost.
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