BOV does it really work?

[Guest]

From what I have heard from my other mates that uses skylines, EVOS they all use Blow Off Valves.

I'm thinking about putting one in my B4 2002, but not sure if its a good idea...I've heard so far that the standard bypass valve was meant to leak at higher boost levels, and a blow off valve would be needed to protect the turbos from compressor surges....

I need some experienced opinions on whether they really do anything other than make a loud noise?

and whats better? Sequential such as HKS BOV's? or regular BOV's like GFB, Turbosmart?

OOPS sorry lol yeah ill go to the search function, I just saw it!

[Johnnynz]

I wont get into the pros and cons because theres a millino people who can explain them better than me floating around.

But you might find the search function helpful, a lot of these sort of questions have been covered before.

Also if you post in the Tech section relevant to your car you will often get people very knowledgable about that particualr vehicle who sometimes dont even set foot in the off topic boards.

[Guest]

im no pro but i heard a BOV makes your car run rich as the ecu doesnt know the air to fuel raito cause the air that gets vented doesnt go back into the engine so it pumps more gas in to fill in the missing air? or something like that haha then again i dun know shit but i still use a BOV anyway the sexyness of it is worth the gas

[Guest]

i would sujest postin the in the tec threads. also, i do think this has been covered in the tech treads somewere.

yes they do cause you to run rich when it releases the air.

it doesnt pump in extra petrol, its just the air that is spose to be there for the petrol has actually be let out into the atmosphere.

the air calculates the right amont of petrol for the amount of air that has passed the airflow meter, when the air is vented, it screws up the calculation and the ecu doesnt actually know.

-smurff

[BC5RA]

ATMO BOV's = Gay

[Johnnynz]

 BC5RA said:

ATMO BOV's = Gay

Legacys too

[Guest]

 Johnnynz']

[quote name='BC5RA said:

ATMO BOV's = Gay

/quote]

Legacys too

haha i agree except for 1st gen's

[Joker]

apart from that fact Plumbback BOV's (which you already have OEM) = slight upgrade

and Legacy's well out number any other make on this forum - and sorry to say BC 1st Gen are becoming less frequent as well!

(whether that is a good thin or bad is yet to be decided)

[Johnnynz]

I wasnt serious anyway, my first Subi was a Legacy.

I just wanted to wind BC5RA up, he likes to poke his tongue at the WRXs so i thought I would give a bit back lol.

[Guest]

haha i just dont like the look of all other legacys and i think its a good thing there not around as much makes have a good decent done up one rare-er

[Swindog]

BOV's have their places, atmo and otherwise. I was having probs surging with the new turbo so a larger bov (venting to atmosphere) was needed. This has all but solved it. Going backwards to a factory plumbback would have probably cured it totally but it wasnt worth the hassle setting it back up again otherwise i would have.

The other thing you can use is a air reticulation valve as seen here... http://www.synapseengineering.com/

You could simply make your own. I think the airforce boys in ohakea used to make them when i was in Palmy. SSS used to sell them.

[BC5RA]

 Johnnynz']

I wasnt serious anyway, my first Subi was a Legacy.

I just wanted to wind BC5RA up, he likes to poke his tongue at the WRXs so i thought I would give a bit back lol.

[quote name='JoKer said:

apart from that fact Plumbback BOV's (which you already have OEM) = slight upgrade

and Legacy's well out number any other make on this forum - and sorry to say BC 1st Gen are becoming less frequent as well!

(whether that is a good thin or bad is yet to be decided)

It's a very very good thing.

[scooby-wrx]

Get one mate... What type is up to you. Different companies make different sound levels. I'd try stick to getting an original as copies can leak and cause other issues... I have an HKS SSQV (not too loud) after experiencing the meaning of compressor surge... Here's a pic of my VF23!

[Swindog]

Your thrust bearings stuffed mate.

See the bent bits on the tip of the fins? Thats not from surge unless the surge has caused bearing failure. Thats exactly how my turbo looked.

[johndoe1003]

isnt tht what compressor surge does? increase load on bearings?

[Swindog]

Not necessarily.

[Pappu1]

the factory blow off does leak at higher rpm at times to ensure that the pressure is not too great at the top end..anyway, the only reason for a near standard suby to have the bov pointing to atmosphere is purely for the noise factor.

as far as engine running rich and all that - its true but not that you would notice much difference normally anyway so dont use that into your decision factor.

if u getting a bov get a good named one as the copy ones can crap out and some leak like a fising net.. HKS SSQ are good for the sound but for the same money a good qualuty turbosmart will be my choice or GFB

anyway, i have a atmo bov and like it purely for the sound to be honest lol..

currently have a hks twin trumpet one for that extra sharp tone

and its not gay to have atmo bov haha lol

(gay = cannon muffler on toyota corollaz..)

[GFB NZ]

Hi SubaruHo,

Just a little info for you re BOV's.

The Suby's have a fairly sensitve Air Flow Meter so if you are going to use an aftermarket BOV it is important to keep some air flowing down that path (as the factory one does) if you don't & you use a 100% atmo BOV you'll get over fueling due to the air/fuel ratio being out of sync.

GFB make a range of model specific BOV's & they make one for your car. It's the GT Hybrid (Bolt On) it is designed to directly replace the factory BOV & comes with the hardware to use it as a 100% plumback or 50/50 setup or if you were off to the drag strip you could use the 100% atmo setup & change it back to 50/50 with just screwdriver.

Here is a link to the BOV & to a page from the GFB website titled "All you ever needed to know about… BOV's" hope this helps & PM if you're interested in purchasing of these BOV's.

http://www.gofastbits.co.nz/index.php?parentid=products&option=products&sub_option=bovs&sub_sub_option=gt_hybrid

http://www.gofastbits.co.nz/index.php?parentid=tech_info&option=tech_info

Brendon

[Joker]

email now works

[Andrew NR]

A vent to atmo BOV will cause a car using a MAF (mass air flow) sensor (like Subarus) run rich when off the accelerator. This can be fixed by fitting a MAP (mass air pressure) sensor. No worries maaaaate

There's no real difference between running a stock BOV and an aftermarket BOV (plumb-back, 50/50 or 100% atmo) except spring tensions which affect leakage and compressor surge.

I also hear that it's perfectly safe to run NO BOV if you are running less than 15 PSI, don't know how true this is

[Pappu1]

 Andrew NR said:

I also hear that it's perfectly safe to run NO BOV if you are running less than 15 PSI, don't know how true this is

na bro - its a no no.. unless u dont love ur cash and wana spend on new turbos

the surge puts a lot of pressure on the bearings

[Andrew NR]

 pappu']

[quote name='Andrew NR said:

I also hear that it's perfectly safe to run NO BOV if you are running less than 15 PSI, don't know how true this is

/quote]

na bro - its a no no.. unless u dont love ur cash and wana spend on new turbos

the surge puts a lot of pressure on the bearings

Yeah, that was my thoughts exactly. It would also cause compressor stall which means you would have to wait for spool everytime you took your foot off the gas, instead of the turbo "free wheeling" until the BOV closes again.

[Glen]

Compressor stall doesn't mean that it stops spinning totally, just that it doesn't 'bite' into the air as usual.

[Swindog]

 Glen said:

Compressor stall doesn't mean that it stops spinning totally, just that it doesn't 'bite' into the air as usual.

Tell that to the guys that have had compressor wheel nuts fly off. Youd be surprised how much the wheel will stall and almost completely stop.

In fact ill try and find the video i used to have of the turbo during massive surge, it shows the wheel doin all sorta things.

[Glen]

 Swindog']

[quote name='Glen said:

Compressor stall doesn't mean that it stops spinning totally, just that it doesn't 'bite' into the air as usual.

/quote]

Tell that to the guys that have had compressor wheel nuts fly off. Youd be surprised how much the wheel will stall and almost completely stop.

In fact ill try and find the video i used to have of the turbo during massive surge, it shows the wheel doin all sorta things.

Sounds interesting. I'm guessing that would be more likely to happen during braking rather than short off throttle periods like gear changes?