BOV's are they really needed.

Ok i have been searching around but cant really find anything i want, so decided to ask the question.

Since going single i have noticed without the BOV connected it makes a lovley flutter sound (air going back into the turbo) but with the BOV connected its not so loud and cant really here it as the whooosh of air it loud and lasts for ages when i let off.

Now my brothers sinlge has a bov and still makes a loud flutter noise.

My question is are the BOV's really needed to let the charge gas escape so it dont effect or break the turbo.

I realise toyota went to alot if trouble to fit them but im sure most if not all rally - racing cars dont run a BOV.

Any info on this would help from the pro's.

Im not a pro but i beleve the fluttery sound is your turbo stalling, The bov lets the air out quickly so it doesnt stall so it keeps momentum and gets to full boost quicker (I think but prob wrong)

I had a mate who thought the flutter sound was the diaphram inside the actuator vibrating back and forth lol.

Anyway back to the question, I would have one simply to keep the turbo spinning after letting off the gas. With out it the flutter sound is the air going back the wrong way over the turbo and out the air filter thus slowing as Blackie said.

You can get different spring strenths in the BOV to let some air escape giving the wooshhhh then a flutter but its all to experiment with....

Hope this helps.

A turbo car will quite happily work without a BOV so no, its not required.

The fluttering noise is compressor stall. Will it have any detrimental affects of turbo longevity, no idea.

Toyota didn't fit a BOV as standard, they fitted a recirculating air bypass valve to get rid of the noise, a BOV is purely aftermarket for making your turbo car sound like a bus

If it improved performance wouldn't all motorsports involving turbos use them and I don't believe any do

This has been debated so much , not just on this forum think all of them I did allot of reading about it but no one seems to be able to give a solid answer . Allot of people seem to think the factory bov's are actually to stop the flutter noise , what bov is your brother running mate ? pretty sure if hes still getting that noise many will say that the bov is not working fast enough or will be in the wrong location . all I know is I blocked off the one on my skyline to try it and it blow a IC pipe blow off so have run one ever since on all my cars .

Try blowing as hard as you can through a straw, now cover the end with you finger and do it again, can't do it as well can you (if at all) thats because it's harder work. Without a BOV to let the air escape or recirc then when the throttle closes and the pressure builds up it gets to the point where the compressor just cannot get any more in (unless a hose gives out or something) this isn't good as the exhaust turbine is trying to turn the shaft and the air on the compressor side is offering resistance, making it work harder.

I've not had a bov fitted for several years with no ill effects, Done maybe 30k miles and still going fine. I think the toyota bypass thingy was there to stop the noises that may have worried joe public. I can't really see the benefit of having one but it is really a personal opinion.

I asked that question last year I think. Chris Wilson doesnt use BOVs, that was enough for me.

Recent thread on bov's

http://www.mkivsupra.net/vbb/showthread.php?264887-Do-we-bother-with-dump-valves-anymore

Interesting, I have a HKS 1 BOV fitted atm & I thought it helped my oem JDM Turbos live longer (no back pressure)

So I might try running without just to see the changes. Is this true what i thought, will it decrease the oem turbo life with BPU?

I have read from jamiep's link that a couple of people have ran for a few years with no BOV or recirculation on BPU?