True, I was being very generic and I know the two do not do the same job.
I was more trying to demonstrate that the lack of either may have
contributed to my destroying a tiny little turbo that was being asked to do
too much in the firstplace.



-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of James Fitness
Sent: Tuesday, 29 July 2003 10:00 AM
To: [EMAIL PROTECTED]
Subject: Re: BOV Sounds


Aren't they 2 different things?
Overboost valve  is placed after the throttlebody
(Like the ones on the Z18 and FJ inlet manifolds)
whereas a BOV goes before the TB

BOV only operate when the throttle is closed
But a OBV operates whenever boost is over a preset
level (10 psi I believe the std Z18 ones are??)

If you really don't want to use a BOV you could always
fit a second throttlebody in front of the turbo so that when
you close the throttle the turbo spins in a vacume... I have
seen a few cars done that way...

James




Geordie wrote:

> Probably, but I doubt the lack of BOV or "overboost safety valve" (as it
is
> on the early 80's turbos) was any help too.
>
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] Behalf Of David Costello
> Sent: Monday, 28 July 2003 8:17 PM
> To: [EMAIL PROTECTED]
> Subject: Re: BOV Sounds
>
> that's more likely to be because the T2's aren't supposed to run much over
> 12psi and they're outside their efficiency range by 14psi, than the not
> having the BOV fitted
>
> Dave
> ----- Original Message -----
> From: "Geordie" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Monday, July 28, 2003 7:08 PM
> Subject: RE: BOV Sounds
>
> > The only time i've ever destroyed a turbo was an oil cooled T2 on a exa,
> and
> > I ha dno BOV and was boosting 14psi out of it. It snapped the turbine
> shaft.
> >
> > The only other thing that could be broken easily is a ceramic exhaust
> wheel
> > shearing off from the shaft.
> >
> > Having said that, I would still not bother with a BOV in most cases
unless
> I
> > was running either very large boost levels or I was running a ceramic ex
> > wheeled turbo.
> >
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] Behalf Of Robert Charles
> > Scealy
> > Sent: Monday, 28 July 2003 2:46 PM
> > To: [EMAIL PROTECTED]
> > Subject: RE: BOV Sounds
> >
> >
> > My old car used to do that with no BOV on closed throttle like you say.
> > I have always been a bit dubious of the theory that air rushing back
> > could damage a turbo though, has anyone ever had any damage that you
> > could attribute to the lack of a BOV? I am no expert though, so I will
> > quite happily hear arguments both ways. My main reasons for being a
> > little dubious are:
> > - If not having a BOV caused turbine damage, every factory car would
> > have a BOV to stop warrany claims etc, but many have no BOV with no
> > problem.
> > - The only place in writing that I have read about BOVs preventing
> > damage to a turbo is in advertisments for BOVs.
> >
> > On Mon, 28 Jul 2003, Reeves Cameron wrote:
> >
> > > with no bov you can probably achieve a similar sound. close the
> intake/off
> > the throttle and the air which would normally escape via the bov rushes
> back
> > through and hits the compressor wheel on your turbo...
> > >
> > > increases lag time and is a perfectly good way to break a good turbo
to
> > boot...
> > >
> > > -----Original Message-----
> > > From: Geordie [mailto:[EMAIL PROTECTED]
> > > Sent: Monday, 28 July 2003 01:59 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: RE: BOV Sounds
> > > Importance: High
> > >
> > >
> > > He's looking for the chirp sound. I'd say that's just some sort of
> > > whistle/trumpet type of BOV, prolly looking at a few hundred bucks to
> get
> > > that dopey sound, but if that's what he wants then go for it.
> > > Far better off without a BOV, pain in the ass to set up, they leak,
> etc..
> > >
> > >
> > > -----Original Message-----
> > > From: [EMAIL PROTECTED]
> > > [mailto:[EMAIL PROTECTED] Behalf Of Ben
> > > Sent: Tuesday, 29 July 2003 5:42 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: BOV Sounds
> > >
> > >
> > > get rid of the BOV.....i dont have a BOV on my SR....she makes a CH CH
> CH
> > CH
> > > CH CH noise when u close the throttle
> > >
> > > ----- Original Message -----
> > > From: <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>
> > > Sent: Sunday, July 27, 2003 7:30 PM
> > > Subject: BOV Sounds
> > >
> > >
> > > > Hi List,
> > > >
> > > > Does anyone know what the relation is between BOV type and sound?
> > > > I have been asked how to get the 'pigeon' sound on a SR20 180sx.
> > > > I think he means the fluttery sound that is NOT wastegate flutter.
> > > > Supposedly you can get it by modifying the installation of a
> Turbosmart
> > I
> > > valve.
> > > >
> > > > Wierd question, I know, but hopefully someone will be able to help
> out.
> > > >
> > > > Thanks,
> > > > Nick
> > > >
> > > > This message was sent through MyMail http://www.mymail.com.au
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > >
> > >
> > >
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> > >
> >
> >
> >
> >
> >
>

--
-----------------------------------------------------------

James Fitness
Director
Data Scribe Australia Pty Ltd
http://www.datascribe.com.au
Computers, Peripherals  and Supplies


Ozdat Online
Webmaster
http://www.ozdat.com




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