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One or Two BOV's? How to decide?

Old 10-03-2018, 09:39 AM
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Default One or Two BOV's? How to decide?

LQ4 with twin BW S366 running up to 25#. Will one TurboSmart Race Port BOV work, or do I need two smaller ones?
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Old 10-03-2018, 10:15 AM
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I'm have same motor same turbos same Bov and I'm literally mocking up to add a second one as we speak it was fine till I got over 12lbs but not its causing surging back towards the turbo
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Old 10-03-2018, 05:53 PM
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Depends on the application etc....none is always an option too.
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Old 10-04-2018, 03:16 PM
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Two gives you twice the possibility for a boost leak.
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Old 10-07-2018, 02:27 PM
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I run 2 billet S476's up to 30+psi, no bov at all
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Old 10-08-2018, 09:35 AM
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Originally Posted by Rob07002 View Post
LQ4 with twin BW S366 running up to 25#. Will one TurboSmart Race Port BOV work, or do I need two smaller ones?
Stick or automatic?
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Old 10-08-2018, 11:13 AM
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I run quad 50mm on a 4.8 with no BOV.

Anti-surge compressor housings help.
Flat shifting your manual helps too.
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Old 10-08-2018, 04:04 PM
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I'm no pro and i'm really new to this, but in my opinion, one would be fine, its job is just to release pressure, right? I dont think that you really need to over think it, as long as you can release the pressure, your good. Plus look at all the guys running No BOV. Some stock vehicles didnt use one either, Namely a Buick grand National. So.........
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Old 10-10-2018, 10:33 AM
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Also called a self cleaning air filter lol. A little hard on the old bearings, but never wrecked a turbo because of it....
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Old 10-22-2018, 07:47 PM
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If journal bearing, I suggest using a BOV. DBB don't care as much.
Autos need them less than stick cars. Or flat foot shift as Joe mentioned.

FWIW, BOV have some mechanical tuning. http://www.turbosmart.com/news/adjus...our-bov-or-bpv
Yours should be fine if installed in correct location.
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Old 12-03-2018, 10:55 PM
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Originally Posted by LSswap View Post
Stick or automatic?
automatic
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Old 12-04-2018, 08:32 AM
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Originally Posted by Rob07002 View Post


automatic
My opinion, one should do it.
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Old 12-04-2018, 04:53 PM
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I never run them but that's just me.
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Old 12-06-2018, 04:01 PM
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Originally Posted by krazy4 View Post
I never run them but that's just me.
drag only car with maybe a quick street hit or cruise to a show, so what would be the downside to not using a bov?
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Old 12-06-2018, 04:24 PM
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I’m no professional. And I may be wrong. But I don’t feel that I am....first off I believe it Don’t take much of a valve to vent the pressure. I put a small, compact valve on mine. As soon as it opens, the pressure is released. Which is what you want, correct? Why do you need two? If one lets the pressure off the turbo, then why would two be better? I don’t think it would amount to a pile beans. Also, wasn’t there a few factory cars, including the grand national, that did not have blow off valves?
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Old 12-06-2018, 05:23 PM
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Originally Posted by Kfxguy View Post
Iím no professional. And I may be wrong. But I donít feel that I am....first off I believe it Donít take much of a valve to vent the pressure. I put a small, compact valve on mine. As soon as it opens, the pressure is released. Which is what you want, correct? Why do you need two? If one lets the pressure off the turbo, then why would two be better? I donít think it would amount to a pile beans. Also, wasnít there a few factory cars, including the grand national, that did not have blow off valves?
Because a need to get rid of 400hp worth of air....is different from a need to get rid of 1400hp worth of air.

Some turbos are more resilient than others in terms of withstanding air stalling or trying to move backwards in the turbo, or indeed rapid speed changes of the wheel/shaft.

Many very old turbo cars did not have any....almost every car in the last 2-3 decades do though.

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Old 12-06-2018, 07:01 PM
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Originally Posted by stevieturbo View Post
Because a need to get rid of 400hp worth of air....is different from a need to get rid of 1400hp worth of air.

Some turbos are more resilient than others in terms of withstanding air stalling or trying to move backwards in the turbo, or indeed rapid speed changes of the wheel/shaft.

Many very old turbo cars did not have any....almost every car in the last 2-3 decades do though.

you right. I just noticed heís doing twin Turbo also. So I guess the right answer would be two smaller ones or one very large one.
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Old 12-06-2018, 09:03 PM
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Here's what scares me without a BOV. 92 mm throttle plate is about 10 square inches. Lets say at 20 psi, you close the throttle. Now you got 20 PSI on one side of the plate and a vacuum on the other side. So let's call it 30 pounds per square inch pushing against a 10 square inch plate or 300 lbs against the plate and shaft.
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Old 12-07-2018, 12:58 AM
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Last car I had was a 94 civic with a Borg Warner S366. Made 400whp on low boost. Drove it for a year, lots of street driving. No BOV.

After a year, there is absolutely no shaft play. Turbo seems brand new. BorgWarners are great though!
Can't say what it would be with some other turbos.

I'm no expert, just sharing my experience.
One less thing to buy, worry about, replace.
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Old 12-07-2018, 02:34 AM
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I cannot imagine a reason for two BOVs. It is really not like the intricacies of proper wastegating. The job of a BOV is quite simple, and you are presumably only running one tube to your throttle body, so I don't even know where you would put an extra BOV.
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