Removing BOV

**Stevie-Boy** · Tuesday 18th November 2008, 12:05

I'm sure this will be an old chestnut for some people and always seems to be a bit of a grey area as to the effects of it.

Basically, I like this noise:

[ame]http://uk.youtube.com/watch?v=IguEOuPvKDs[/ame]

My Primera GT Turbo used to make that noise and I prefer it to the BOV noise.

Can this noise be created just by removing the BOV and more importantly, will it cause damage to the tub?

**pangster** · Tuesday 18th November 2008, 13:32

Originally Posted by Stevie-Boy

I'm sure this will be an old chestnut for some people and always seems to be a bit of a grey area as to the effects of it.

Basically, I like this noise:

http://uk.youtube.com/watch?v=IguEOuPvKDs

My Primera GT Turbo used to make that noise and I prefer it to the BOV noise.

Can this noise be created just by removing the BOV and more importantly, will it cause damage to the tub?

that sounds like compressor surge to me.. I personally wouldn't want to hear it on my car as its the compressed air hitting off the throttle plate and being passed back through the turbo.. not sure how harmful it would be on a normal turbo/bearings but I *think* it is not as problematic/harmful on a BB turbo.. can't imagine it would be good in the long run either way though..

better video/explanation of it here:

[ame]http://www.youtube.com/watch?v=LZUbo_mNDZM[/ame]

HTH

**Yosser** · Tuesday 18th November 2008, 14:02

Perhaps this is the noise you REALLY want:

[ame]http://uk.youtube.com/watch?v=lZG0RS3mVBc[/ame]

**pangster** · Tuesday 18th November 2008, 14:16

Originally Posted by Yosser

Perhaps this is the noise you REALLY want:

http://uk.youtube.com/watch?v=lZG0RS3mVBc

FPMSL!!!!

**Stevie-Boy** · Tuesday 18th November 2008, 14:47

Old vid LOL, I'll skip that I think. If I wanted daft responses I'd have posted this in the off topic section rather than the modification area cheers.

Well, I've seen some pretty serious 200sx running with the above noise (not the duck) and it sounds well nice. Much better than the psssst that everybody has.

Watch this video around 1m30, best example is around 2m.

[ame]http://uk.youtube.com/watch?v=CJlR_zIwmiE[/ame]

Seriously modded car so it can't be deemed as being chavvy?

**Mrsmopp** · Tuesday 18th November 2008, 14:53

Originally Posted by Stevie-Boy

Seriously modded car so it can't be deemed as being chavvy?

Chavvy is when its a noise created just for the amusment of the owener and not for any performance gains....a lot like spinning rims, bean can exhausts etc

x

**Stevie-Boy** · Tuesday 18th November 2008, 15:00

I was more leaning towards saying that by asking about compressor surge noise, I've had a stupid duck noise back so am assuming that to the masses, any sort of noise is stupid right?

**Yosser** · Tuesday 18th November 2008, 15:31

Sorry Stevie-Boy, no offence meant - I just really love that duck call vid!

I personally don't have a BOV but I don't mind the noise of them, in fact I have considered fitting one in the past (wouldn't totally rule it out in the future).

A lot of people argue that it's a 'cosmetic' mod because there is no performance benefit from replacing the CBV with a BOV - although above a certain boost pressure I think there is a benefit.

There's another thread on surge on volvospeed : http://volvospeed.com/vs_forum/index...owtopic=103524

**tempo** · Tuesday 18th November 2008, 16:37

im sure thats something to do with how far the wastegate is open. my old suzuki swift gti turbo did that. i agree that it sounds better.

tempo

**pangster** · Tuesday 18th November 2008, 16:59

Originally Posted by Stevie-Boy

I was more leaning towards saying that by asking about compressor surge noise, I've had a stupid duck noise back so am assuming that to the masses, any sort of noise is stupid right?

I think MrsM is meaning that in order for the turbo to make the noise you like.. what physically happens is that the pressurised air that cant escape anywhere else on lift off i.e. normally would be recirculated (re-circ valve) or vented to atmosphere (blow off valve) now only have one direction to go - back where they came. The noise is caused because the compressed air is hitting the turbo fins in the wrong direction (turbo spinning the wrong way) which causes it to momentarily stall. If you then apply the throttle and create boost then the turbo has to start spinning the correct way again - in theory this will take longer(increased lag time)/have a detrimental effect on performance due to fins spinning the wrong way making that noise you like. But WRC teams and the like get around this by fitting ball bearing turbos and anti-lag systems which are effectively creating boost all the time.

**pangster** · Tuesday 18th November 2008, 17:02

Originally Posted by tempo

im sure thats something to do with how far the wastegate is open. my old suzuki swift gti turbo did that. i agree that it sounds better.

tempo

nope - "wastegate chatter" (which I think is what you are referring to) is a myth... the sound the OP is talking about is definately turbo stall/turbo flutter/compressor surge.

**pangster** · Tuesday 18th November 2008, 17:03

Originally Posted by Yosser

Sorry Stevie-Boy, no offence meant - I just really love that duck call vid!

I personally don't have a BOV but I don't mind the noise of them, in fact I have considered fitting one in the past (wouldn't totally rule it out in the future).

A lot of people argue that it's a 'cosmetic' mod because there is no performance benefit from replacing the CBV with a BOV - although above a certain boost pressure I think there is a benefit.

There's another thread on surge on volvospeed : http://volvospeed.com/vs_forum/index...owtopic=103524

I'm pretty sure I read there was no performance benefit to a BOV unless running >20 psi which on our engines isn't something you'd want to do without forged rods in any case as that's rod bending material from what I've read!

**Mrsmopp** · Tuesday 18th November 2008, 17:09

Originally Posted by pangster

I think MrsM is meaning that in order for the turbo to make the noise you like.. what physically happens is that the pressurised air that cant escape anywhere else on lift off i.e. normally would be recirculated (re-circ valve) or vented to atmosphere (blow off valve) now only have one direction to go - back where they came. The noise is caused because the compressed air is hitting the turbo fins in the wrong direction (turbo spinning the wrong way) which causes it to momentarily stall. If you then apply the throttle and create boost then the turbo has to start spinning the correct way again - in theory this will take longer(increased lag time)/have a detrimental effect on performance due to fins spinning the wrong way making that noise you like. But WRC teams and the like get around this by fitting ball bearing turbos and anti-lag systems which are effectively creating boost all the time.

Errrrmmmm I'd have liked to have meant that.........

x

**pangster** · Tuesday 18th November 2008, 17:12

Originally Posted by Mrsmopp

Errrrmmmm I'd have liked to have meant that.........

x

**tempo** · Tuesday 18th November 2008, 17:46

Originally Posted by pangster

nope - "wastegate chatter" (which I think is what you are referring to) is a myth... the sound the OP is talking about is definately turbo stall/turbo flutter/compressor surge.

well thats something i never knew. learn something everyday!! hehe

tempo

**Engineer** · Tuesday 18th November 2008, 18:16

Sometimes nothing is ever that simple, read link below and ask yourself why Russ is now considering using a compressor by- pass system when he originally said they were not needed............is it the size of the turbo or the boost or both? I certainly would not need one on my car if it was just for performance as its auto..........

http://forums.t5d5.org/index.php?showtopic=3662&st=60

**irf** · Tuesday 18th November 2008, 18:35

on my 200sx i took mine off. loved the sound!! how couldn't you??

on the sxoc i was shown a link that said that up to 1.4 bar it was okay not to run one.

then i bought a brand new GT28RS. didn't want to take the risk so i chickened out and put the dump valve back on

i've tried it with the volvo and for whatever reason it's nowhere near as loud. the way i have my dump valve set up now is for it to only dump at near enough peak boost.

**dangerstevie** · Wednesday 19th November 2008, 12:38

On my old renault 21 turbo when i first got it, it was running 28PSI boost and i had a forge group A dump valve on that, i sold it to my brother after 6 mths of trouble free motoring and to get the same noise you are after he took off the dump valve and less than 500 miles later he was sat at the side of the road with a turbo minus most of its blades on the turbine wheel and all of the blades from the compressor wheel nicely stuffed into my Cossie intercooler core!
This failure was due to the high boost level + no dump valve. i then bought it back off him and rebuilt it all refitted the dump valve and was running 16psi at 249bhp for the rest of its life, and i believe its still running the same setup (at last contact with new owner 12 mths ago)
I love the turbo chatter noise but the sound of a HKS SSQV is just sex on a stick and its going to help keep things safe too. which is why i am fitting one to mine instead of the bloody silly bailey dv26 thats on there at the mo

**Stevie-Boy** · Wednesday 19th November 2008, 13:38

Thank you all for the comments, very useful and has convinced me to enjoy the noise but to let it stay on other peoples cars!

Sorry for being a bit radge earlier on, I wanted it to be a serious discussion and when the duck post came, I thought it was just going to turn into one big piss take.

**Yosser** · Wednesday 19th November 2008, 14:04

Originally Posted by Stevie-Boy

Sorry for being a bit radge earlier on, I wanted it to be a serious discussion and when the duck post came, I thought it was just going to turn into one big piss take.

Sorry, thats my fault.

The whole duck call dump valve thing gets me every time

I might even consider fitting one myself