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BOV- What's the point?

Mase

By Mase,
in Engines & Forced Induction

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Mase Mentor

Mase

Posted
Posted

What's the point of a an aftermarket bov besides its sound and if you are running excessive amounts of boost. I have searched and some say it keeps the turbo spinning cuz it vents the built up pressure but others say it doesn't do anything unless you run more boost than the stock bov can handle.

Any info would be appreciated.

Cheers

Jayson

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https://www.sau.com.au/forums/topic/31585-bov-whats-the-point/
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cameron Mentor

cameron

Posted
Posted

eg: HKS BOV is designed not to leak boost when under load an it releases all the pressure through the bov, it keeps the turbo spooling because its not plumbing back.

Standard plumback. the standard r33 gtst bov is designed to leak an it plums the pressure back through the turbo ? which causes the fins to chop it up an it slow the turbo down. (lag)

correct me if im wrong!!! :D

paulr33 Grand Master

paulr33

Posted
Posted

See: http://www.skylinesaustralia.com/forums/sh...ead.php?t=31552

Similar conversation covered. The vl turbo doesnt have a bov, ask how many mates u know have vl turbos and have killed their t3/t4 from surging :D

A bov is required for proper turbo operation. Be it stock boost vs 18psi.

Without a bov, you have compressor surge, flutter noises and high pressure back spinning the compressor wheel

Perhaps a guru could comment: SydneyKid?? :D

paulr33 Grand Master

paulr33

Posted
Posted

The stock r33 gtst bov leaks to the atmo, it wont leak through the piping. Theres a thread covered recently about the "free stock bov mod" which shows you how to stop it leaking.

I *think* the leaking is a safety feature nissan put it on so it doesnt overboost itself

Mase Mentor

Mase

Posted
  • Author
Posted

sorry i should have reworded it. What's the point of buying an aftermarket bov against keeping the standard one. So it keeps the turbo spinning with less back pressure but would the stock one do that just as well on my rb20det? I have an rb25det top cooler pipe so it fits better with a strut brace in my silvia

paulr33 Grand Master

paulr33

Posted
Posted
sorry i should have reworded it. What's the point of buying an aftermarket bov against keeping the standard one. So it keeps the turbo spinning with less back pressure but would the stock one do that just as well on my rb20det? I have an rb25det top cooler pipe so it fits better with a strut brace in my silvia

Yes the stock one will do just that. However the stock one will probably be in-efficient past 1.5 bar boost. Once you go near 17psi ish I would get an aftermarket one "to be sure, to be sure". The stock one will leak a fair bit up near 1.5bar. Of course it should still work correctly

nissky Community Regular

nissky

Posted
Posted

i just tried out a GFB blow off valve on my R32 running r34 turbo and 14psi....

its the mach1 the loudest they make, its an instant defect but sounds cool in tunnels i cant hear the exhaust with this thing on

you can change gears without it going off though if you have to (lifting off slowly)....

but in terms of performance it does jack all! if anything the turbo was taking longer to spool up within 3000-4000rpm, the turbo feels like it kicks in harder

but thats only because theres more lag in the mid range, and no theres nothing wrong with it...its almost brand new

i think the stock bov, does keep the turbo spinning faster with the small leak which causes it to spool up quicker when you accelerate, the size of the hole on the stock valve i dont think is going to cause much of a leak at 14psi (maybe 0.5 - 1psi), but then my boost controller would compensate and still keep it at 14psi...

in my opinion save your money, nissan designed it well....unless you have massive turbo with big boost....

again this is my opinion...but yeh 2 days later im back to stock bov :wassup:

soon up for sale, GFB mach1 blow off valve as new with rb20 adaptor pipe that connects to stock bov location $150 :(

an aside: i didnt have any issues with stalling etc, with this atmo venting valve on my car...

!!!!GFB bov for sale ...click here!!!!

GTRman1992 Proficient

GTRman1992

Posted
Posted

I don't believe the BOV propoganda (only needed with massive turbo's). I don't have one at all, run 20PSI boost and spin the wheels from 1st to 2nd and 2nd to 3rd. So there is no loass of power without one. Also it has been like this for 3 years and all is fine.

If you have a think about it, a pressure wave from the throttle body running all the way back down the induction system (full of 90deg bends which call big losses on pressure waves in a compressible medium) through the intercooler core and hitting the turbo blades with any impact is nonesense. Especially as the medium it is travelling in is collapsing anyway. Also consider the volume of air in there, for a pressure impact you have to raise the pressure of that entire volume, with a turbo that is no longer being spun by exhaust gas for the 2tenths of a second the throttle is shut.

I'm just not a believer.

JimX Grand Master

JimX

Posted
Posted

I don't know how my a/m bov compares to factory, but it seems to work quite well. It's quiet, I don't lose power/boost between gear changes, and it doesn't even open at low revs. Because of that I get slight turbo flutter but I don't think it's anything to worry about. I could adjust it to open sooner but then it'd just be noisier and open at low revs and thus attract more unwanted attention from the cops.

It came with my car when I bought it, so although there may have been little point to change the factory item to this one, because it does the job well enough there is also little point to swap it back to the factory one.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

one thread of interest

http://www.skylinesaustralia.com/forums/sh...ead.php?t=30788

and another - main post of interest from Bozz

http://www.r31skylineclub.com/forum/index....y;threadid=6601

Basically.

bet a plumb back one. the Bosch ones work well... and cost around $60.

DJ984 Mentor

DJ984

Posted
Posted
i just tried out a GFB blow off valve on my R32 running r34 turbo and 14psi....

its the mach1 the loudest they make, its an instant defect but sounds cool in tunnels i cant hear the exhaust with this thing on

you can change gears without it going off though if you have to (lifting off slowly)....

Sorry to chop you mate but GFB quote themselves that the hybrid is louder... along with a lot of others they make....

You can also adjust them so it goes off later so that you can drive around and just have it flutter under certain RPMs (as i do with my GFB Hybrid)....

Skyrine-Dave Mentor

Skyrine-Dave

Posted
Posted
Sorry to chop you mate but GFB quote themselves that the hybrid is louder... along with a lot of others they make....

You can also adjust them so it goes off later so that you can drive around and just have it flutter under certain RPMs (as i do with my GFB Hybrid)....

Sorry to chop you mate but...

The loudest valve in the range, the Mach 1 will let people know you're coming!

aside from that... we are not discussing who's bov is louder. we are discussing whether you need an aftermarket bov or if the factory item will suffice.

Gson Enthusiast

Gson

Posted
Posted

well i think it is definatly a must to run a blowoff valve! i heard that the flutter noice was the compressor turbine being spun the opposite way by the returning pressure! sounds very bad to me!

also atmospheric blow off valves definatly do the job of releasing pressure but isn't this only half the power of a bov! plumbed back air into the intake is the other streanght!

thus any one searching for performance should choose a plumb back!

GTRman1992 Proficient

GTRman1992

Posted
Posted

As I said above, my car spins the wheels from 1st to 2nd and 2nd to 3rd so I don't believe the loss of power theory. I run RE-540S semi slick tyres so the grip is high ! Read my item above. Anyway, what flutter noise. Have you run the car without the BOV and heard it ?

The pressure you hear being released is your normal boost pressure. The way I see it is that if you vent it off then you have to build it up again before being on boost again. So a BOV would actually slow down the boost between gears.

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