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Discussion Starter #1
I'm a n00b to turbo, so I have to ask, while I know a BOV is useful in reducing wear on the turbo, since we already have an internal redirector or whatever, is there any benefit to the engine/turbo in having the BOV?

I talked with a guy today who says he's been working on turbo motors for 20 years, and he says that a BOV will likely only make the car run richer. It won't necessarily help, other than adding a cool sound.

Another friend (with a 650whp Supra) says that BOVs are generally much better built than OEM redirectors, so it may be a worthy upgrade.

Comments?
 

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the Supra guy is on the money cause if the car would run rich then why does it come wwith one from the factory :roll: :wink: . Anyhow they do provide both usefullness aswell as amuzement. The reason most BOV get louder is mainly due to either how its tuned or how much air you are moving through it. The worst thing you can do is run high boost, blow the seat on the stock BOV and get compressor surge like a mofo. I used to own a Blitz SS BOV i loved the thing to death but it wasnt cheap so i traded it for some parts. It was loud and effective but i think im going for the TurboXS or a crushed 1st gen DSM unit for the Omni. Get one you wont regret it when you turn the boost up
 

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What is the difference between say The Blitz, TurboSX, and HKS?
 

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acr2nv said:
i think im going for the TurboXS
Type-H, why that one?
 

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You guys have a lot to learn:

1) Aftermarket BOVs are louder because they are vented to atmosphere instead of back into the intake

2) Aftermarket BOVs might be necessary at higher boost levels as most stock BOVs will leak and/or start to fail much above stock boost levels. No one to my knowledge has done this research on the SRT-4's BOV to date, I suspect it has a higher threshold than most with the stock boost capable of hitting 15psi.

3) Aftermarket BOVs can cause unexpected results due to incorrect air calculations (based on what I've seen of the SRT-4's ECU this won't be a problem) and/or surging due to different speeds in boost pressure release, particularly at partial boost.

Overall, probably not going to hurt anything by throwing one on the cars now other than your bank account. FWIW, it might be wise to leave both connected, shouldn't cause any harm...has anyone tried a stock+aftermarket BOV setup yet?
 

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srt4evah said:
I talked with a guy today who says he's been working on turbo motors for 20 years, and he says that a BOV will likely only make the car run richer. It won't necessarily help, other than adding a cool sound.
:roll: Don't let him touch your car.

There are some minor differences between a BOV, Surge Valve, "Shift Valve," and Bypass Valve, but at this point, who cares? The SRT-4's is called a Surge Valve, which is the correct name for it.

When you have your foot into it the turbo is pushing lots of air into the intake. When you let off the throttle to shift, or for any other reason, the TB (throttle body) blade closes and all of that air between the turbo and the TB has no place to go. The turbo is still spinning and trying to push air into the intake.

As the pressure builds up it bounces back off the closed TB blade and heads back through the plumbing and slams back into the turbo. The pressure wave is enough to stop the turbo from spinning (or at least slow it down a whole bunch), and it will actually go through the turbo and out the air intake. When this happens you can hear it, sometimes described as "fluttering." It's bad for the turbo because it puts a big strain on the bearings, causing premature shaft wear usually.

The surge valve prevents this by opening up when the TB blade closes. When the SV is open the air that is being produced by the turbo will be vented throught the SV instead of being slammed back and forth between the TB and turbo. On the SRT-4 the SV vents into the exhaust, but a BOV (or other types of valves) can be vented to atmosphere too. Then you get that nifty sound that everyone likes! 8)

As a bonus, the SV allows the turbo to continue spinning so you don't have to wait for spool up after shifting gears. As soon as you open the TB blade again the SV closes and the boost is there waiting for you! :D
 

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Discussion Starter #8
So Mike, is there any advantage to having a BOV given the presence of the stock SV? Other than the sound?

Any downsides? Would the car actually run richer with the BOV than the stock SV?
 

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I'm not sure if a BOV would be better, but it most likely will. Most factory valves will begin to lift and bypass air at low boost pressure. That's not good because you want that air going into the intake, not being bypassed to somewhere else. Aftermarket BOV's usually have stronger springs and allow you better control over when it opens. Until someone gets the time to do some testing we don't know for sure when the stock valve begins to open. Personally, I don't plan to buy an aftermarket BOV until I'm sure that the stock one is not good enough.

I don't know where your mechanic friend gets the idea that a BOV makes the car run richer. That's a new one on me. Makes no sense. :?:
 

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Is it common for people to leave the stock "BOV" or in this case, the SV connected and run an additional aftermarket BOV? What advantages/disadvantages could that present?

"What? You only have one BOV? That sucks. I have two."
LoL.
 

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When the air enters your MAF, the ECU sees X amount of air entering it, so it puts out Y amount of fuel. When you install a bov that vents, you now have X-Vented air amount of fuel so the car is richer. Next time you drive behind an eclipse or something that has a MAF, you will notice black smoke come out when they shift, thats cause the car is a little richer after teh shift.

This is not an issue with us because we dont have a MAF, we have a MAP thats located in the manifold.

WHen I installed my BOV, i noticed a quicker recovery with the 15psi that im running now. THe turbo came back online after the shift sooner than with out the bov.

 
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