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Location:
EPPING SYDNEY
Registered:
June 2003
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Which BOV is the best
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Mon, 17 May 2004 12:10
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Which BOV has best sound and performance, I have been told Greddy Type R and Blitz is pretty good, how bout apexi and other brand?
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I supported Toymods
Banned User
Location:
Brisbane
Registered:
May 2002
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Re: Which BOV is the best
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Mon, 17 May 2004 12:21
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HKS SSQ.
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Location:
Wahroonga
Registered:
June 2003
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Re: Which BOV is the best
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Mon, 17 May 2004 12:38
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i use a turbo smart type II BOV, i'm happy with it.
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Location:
Brisbane
Registered:
May 2002
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Re: Which BOV is the best
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Mon, 17 May 2004 13:17
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Pretty much any BOV, including the one fitted from the factory, will "perform" just fine. As for sound, that's a purely subjective thing but personally I'd prefer totally silent. Yet another reason to keep the stocker!
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Location:
Adelaide
Registered:
May 2002
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Re: Which BOV is the best
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Mon, 17 May 2004 13:19
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Blow off valve sound and performance are mutually exclusive.
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Location:
sunny coast, qld
Registered:
October 2002
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Re: Which BOV is the best
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Mon, 17 May 2004 13:33
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and what the hell does it mean whey the advertise the Blitz BOV's to handle up to 800hp? I really don't understand that?
I like my stocko also unless it leaks it will be staying there.
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Location:
adelaide
Registered:
April 2003
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Re: Which BOV is the best
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Mon, 17 May 2004 13:33
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| Norbie wrote on Mon, 17 May 2004 23:17 |
Pretty much any BOV, including the one fitted from the factory, will "perform" just fine. As for sound, that's a purely subjective thing but personally I'd prefer totally silent. Yet another reason to keep the stocker!
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norbie gets the pro_ke seal of approval
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Location:
Wahroonga
Registered:
June 2003
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Re: Which BOV is the best
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Mon, 17 May 2004 20:44
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| Chris Davey wrote on Mon, 17 May 2004 23:33 |
and what the hell does it mean whey the advertise the Blitz BOV's to handle up to 800hp? I really don't understand that?
I like my stocko also unless it leaks it will be staying there.
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what would the horsepower have to do with a BOV? Its the psi that it has to deal with not the hp.
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Location:
Brisbane, QLD
Registered:
February 2003
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Re: Which BOV is the best
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Mon, 17 May 2004 21:04
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| Draza wrote on Tue, 18 May 2004 06:44 |
| Chris Davey wrote on Mon, 17 May 2004 23:33 |
and what the hell does it mean whey the advertise the Blitz BOV's to handle up to 800hp? I really don't understand that?
I like my stocko also unless it leaks it will be staying there.
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what would the horsepower have to do with a BOV? Its the psi that it has to deal with not the hp.
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probably trying to indicate that an engine with a turbo producing that much power will also be producing alot of boost
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Location:
Wahroonga
Registered:
June 2003
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Re: Which BOV is the best
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Mon, 17 May 2004 22:12
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yea i guess for those that know bugger all it sounds better saying 800hp than saying 35psi.
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: Which BOV is the best
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Mon, 17 May 2004 22:44
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think about it, a BOV (or an engine) has to deal with flow rate of air as well as boost pressure,
rating a BOV at 800 hp is entirely valid, it means that it will pass 800hp of air, as opposed to a small one, get it?
although you could just use four cheap ones, which is i would probably do....
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Location:
Brisbane
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 03:33
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No BOV will flow "800hp of air". Do you have any idea how much air that is??
No, rating a BOV to 800hp is nothing more than a wank. I reckon most factory BOV's would work OK at that power level, except they'd probably leak because of the higher pressures involved. That's really the only valid reason to upgrade your BOV, and in some cases this is necessary with even modest boost increases (eg MA70).
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Location:
c'town, NSW
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 04:17
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| Norbie wrote on Tue, 18 May 2004 13:33 |
except they'd probably leak because of the higher pressures involved. That's really the only valid reason to upgrade your BOV....
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thats probably the last reason to want to upgrade, the main reason to upgrade is for street cred. 
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Location:
Brisbane
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 04:44
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You're right of course. My bad.
I might add that my Blowoff Can (tm) makes my Supra sound like a city bus. SIK!!
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Location:
Elwood, Melb
Registered:
August 2003
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Re: Which BOV is the best
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Tue, 18 May 2004 06:40
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I've discussed this with a few mates, because when i get my 3s-gte (st205) it will come with the stock bosch bov, which is fine, but in my opinion a plumb-back bov would suit me best personally because it doesn't vent out into the atmosphere, which = less noise, but it really depends on how much power you're making as an atmospheric bov would suit something with lots of power or a rice box that loves the sound, thats why drag cars use them because they don't have to worry about noise and it lets off extreme levels of pressure. If your making 800hp then your going to deal with higher levels of pressure, right.
But i've never really heard of bov being rated by hp, only turbos.???
Someone please shut me down if i am wrong, i won't care, this is just my understanding, so if i am wrong it will help me understand, right.
Thanks
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Location:
cambo
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 07:13
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while we're on the subject, anyone got a prof sheepdog forsale? if so pm me.
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Location:
South Australia
Registered:
July 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 07:26
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| Quote: |
Blow off valve sound and performance are mutually exclusive.
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Okay this is a legitimate question - if that is the case then why do all world rally cars etc have loud(ish) blow off valves?
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Location:
cambo
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 07:41
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not lately they arent. and i would say its because an externally venting one has the potential to discharge more air than a plumb-back one which has to redirect the air to a pipe. they also dont have to worry about noise polution 
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Location:
EPPING SYDNEY
Registered:
June 2003
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Re: Which BOV is the best
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Tue, 18 May 2004 08:22
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how do u know if your bov is leaking ?
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Location:
On your mum!
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 08:27
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A plumbed back (re-circulating to be technically correct) BOV will actually outperform a vented to air jobby if it is thoughtfully installed, all while sounding 385 million percent better.
A large compressor will be pumping a lot of air on closed throttle - meaning that the BOV needs to be able to cope (I can tell you that the Turbosmart type III on my car struggles to cope with the GT30 - I base this judgement on the fact that I can hear compressor surge on gear changes).
I agree with Norbie - 800hp is a shitload of air and that it is little more than a nice sales figure.
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Location:
Canberra
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 08:40
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Why should any blow off valve leak, when there is supposed to be equal pressure on both sides of the valve when on boost? Only reason I can see is if your BOV is mounted before the intercooler, and you have a large pressure drop across the intercooler core, in which case the pressure on top of the valve (referenced through the vacuum/boost hose to the inlet manifold) might be 10psi, whereas the pressure under the valve was 14psi (assuming in this case a 4psi pressure drop across the cooler)
agree/disagree? 
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Location:
Sydney
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 09:28
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i never wanted to touch my factory BOV it was so responsive!
the time came when my factory one stuffed up so i installed one that some one had given to me (thanks man you know who you are)...I WAS AMAZED!!! this BOV was more responsive that the factory one!!!
so guyz i'm backing the GFB (Go Fast Bits) all day every day i was very suprised to say the least!!!
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Location:
Brisbane, QLD
Registered:
February 2003
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Re: Which BOV is the best
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Tue, 18 May 2004 11:25
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| rob_RA40 wrote on Tue, 18 May 2004 14:17 |
| Norbie wrote on Tue, 18 May 2004 13:33 |
except they'd probably leak because of the higher pressures involved. That's really the only valid reason to upgrade your BOV....
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thats probably the last reason to want to upgrade, the main reason to upgrade is for street cred.
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how can you argue with logic like that? 
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Location:
I wanna go Hawaiiiiii.......
Registered:
November 2003
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Re: Which BOV is the best
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Tue, 18 May 2004 12:45
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To say there is no benefit to having a High performance BOV is total crap. Just as bad however is to beleive there is any significant performance gain to be had by having one.
There is a need to have a high flowing BOV when coupled with a large turbo. Even the most expensive BOVs are not up to some performance applications, HKS Super sequential would have to be the best example, lots of intricate ricey parts and bees dick flow capacity. They do however produce high air velocity (hence big noise) even on pissy little stock turbo setups.
A decent turbocharger pumps enough at a suddenly closed throttle that a small bov cannot release enough and impeller reversion occurs (not compressor surge) which can be heard as air escapes past the impeller blades and out the air filter. This is often mistaken by NA enthusiasts, children and ricers as the "fully sick BOV noise".
Ever noticed that the more you tighten the spring on your BOV the funkier the noises it produces ?? Its because it isnt opening - perhapps at all - and all you are hearing is your turbo spinning the wrong way!!
So my point - big BOVs are best.
I have a Blitz DD BOV - probably the biggest of the ricer bovs - and most expensive. But for serious performance it will not be enough for a big single application.
Go the Vortech Mondo or the big bad Greddy.
If you cant fit your mobile phone in the outlet you are wasting your time !
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Location:
On your mum!
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 13:22
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Not trying to start an argument, but the noise is not necessarily impeller reversion - it slows down so that pressured air cannot be contained by the impeller - that is compressor surge which is air reversion - absolutely. Compressor reversion is a worst case scenario (small turbos with low inertia coupled with lots of boost will reverse easier) and can result in broken turbine shafts.
I've heard people ask on a few occasions about which BOV that somebody has got - when indeed there was no BOV fitted - and then go on to challenge the response when told that there is no BOV.
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Location:
Terrigal
Registered:
May 2002
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Re: Which BOV is the best
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Tue, 18 May 2004 23:43
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| Quote: |
I've heard people ask on a few occasions about which BOV that somebody has got - when indeed there was no BOV fitted - and then go on to challenge the response when told that there is no BOV.
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Hmm yes i've had people question what BOV I have more than once now. I let them know there isn't one in use. They then go on and inform me that I must be wrong and there is indeed a BOV in there somewhere.
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Location:
I wanna go Hawaiiiiii.......
Registered:
November 2003
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Re: Which BOV is the best
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Tue, 18 May 2004 23:54
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Agreed - not trying to start arguments - I did sound a little aggressive.
Compressor Surge is a term widely overused much like "Lag" by many with a very loose understanding of turbocharger behaviour.
Obviously not the case with Jase.
I hadnt really thought of this situation as being surge - as surge in the on boost sense(the usual use of the term)would never result in impeller reversion as it can with the closed throttle situation. But Jase is right, up to the point of reversion this effect should be called surge.
Still supports my theory of the mobile phone test for BOV flow.
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Location:
Canberra
Registered:
June 2003
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Re: Which BOV is the best
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Wed, 19 May 2004 03:13
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Some good points being raised but one that has been missed is the design used. Piston types, like turbosmart etc, are easier/cheaper to make but from my experience don't seem to have the flow capacity of the valve type BOVs. I have both a GReddy Type R (BIG piston) and a turbosmart type II and both work well but the GReddy is clearly the better performer.
The valve type design simply allows better airflow and more flow per movement as well.
Boost isn't the only consideration either, mass flow is also important as i think has been mentioned. Both reversion and surge seem to increase as the mass of air moved increases. Conceptually this seems logical to me but i'm not sure of the exact physics. A bigger BOV helps by moving more air. On the same engine at the same boost (and no leaks) a Blitz BOV did almost nothing to reduce reversion whereas the Type II cured it completely.
On my TT V8 reversion is HUGE, i have no BOV as yet and the noise on gear change is louder than most BOV's you'll hear. I have my fav BOV, a GReddy Type R ready to go on asap. It'll be plumb back so hopefully it'll quieten things up a lot.
as an aside i have a spare Type R FS is any is chasing one. Hell expensive new but i'm open to offers.
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Location:
On your mum!
Registered:
May 2002
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Re: Which BOV is the best
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Wed, 19 May 2004 08:40
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All is well Matt - I didn't want to start on a physics lesson since you are doing so well at it..
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Location:
I wanna go Hawaiiiiii.......
Registered:
November 2003
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Re: Which BOV is the best
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Wed, 19 May 2004 09:30
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| YelloRolla wrote on Wed, 19 May 2004 18:40 |
I didn't want to start on a physics lesson since you are doing so well at it..
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I may have to take industrial action if you were to do that. Gotta protect my livelyhood.
Just think yourself lucky I didnt set you any homework.
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Location:
adelaide
Registered:
April 2003
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Re: Which BOV is the best
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Wed, 19 May 2004 09:43
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an interesting point to note is that the official mazda line on why BOVs are fitted to their turbo rx7s from the factory is 'to reduce turbo noise'
also note that f1 cars never used bovs in the 80s and indy cars dont either...
i dont see any reason to 'not' use one but if i had a turbo car its not something i would personally spend any money on. actually i would probably never build or buy a turbocharged car so its of no concern to me 
ab
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Location:
cambo
Registered:
May 2002
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Re: Which BOV is the best
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Wed, 19 May 2004 10:50
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o/t again but...
does anyone have any opinions on the sard R2D2 bov's? i know they arent recirc but im more concerned with flow capability. needs to handle approx 22psi on a ct26/t4. was wanting a recirc but i figure if im driving around town i wont be on boost so wont make noise anyway unless i push it
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Location:
On your mum!
Registered:
May 2002
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Re: Which BOV is the best
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Wed, 19 May 2004 12:41
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Do not believe that if you are not on boost that your BOV will not make noise - they are quite loud when off boost even because the comp is spinning and is moving plenty of air, the BOV then opens because of a vacuum signal in the plenum. I got shitted with the noise of my BOV in about 2 days - but I am tolerant because I haven't done anything to change it yet
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Location:
Gold Coast
Registered:
January 2003
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Re: Which BOV is the best
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Wed, 19 May 2004 13:11
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just a stupid question but on time i heard from soemone or rear can't remember but are BOV to teh atmosphere illegal well in queensland??
Nezza 
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Location:
On your mum!
Registered:
May 2002
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Re: Which BOV is the best
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Wed, 19 May 2004 13:13
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Illegal in NSW too - the nice officers at Thornleigh maccas pointed this out for me; along with some other things as well
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Location:
Gold Coast
Registered:
January 2003
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Re: Which BOV is the best
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Wed, 19 May 2004 13:38
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ummm ok, well i need my car legit cause i'm crusing around on 1 point for 12months thingy, so i might wait for a GFB stealth/race one. race mode for when u want to so off, but stealth the other 90% of time.
Nezza
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Toymods Board Member
I supported Toymods
Location:
Turramurra, Sydney.
Registered:
May 2002
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Re: Which BOV is the best
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Wed, 19 May 2004 14:45
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| TE72_Turbo wrote on Tue, 18 May 2004 18:40 |
Why should any blow off valve leak, when there is supposed to be equal pressure on both sides of the valve when on boost?
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This I'd also like to know, as I'm planning on using one of the little black plastic bosch bovs, which I've heard can leak above 1bar. If there's equal boost pressure on both sides of the BOVs diaphragm, plus the pressure of a spring on the helping keep it closed, it should stay closed. Unless maybe there's less area for the pressure to act on on the map signal side.
In which case, how well would plumbing the BOV up backwards work, so instead of the vented air pushing against the valve to open it, it's pushing it closed until the manifolds vacuum signal was enough to open the valve against this pressure to vent said pressure.
Does anyone reckon this would work?
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Location:
Sydney
Registered:
May 2002
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Re: Which BOV is the best
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Wed, 19 May 2004 15:00
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huh? getting way to tech there dewd just hook her up as normal and it'll work fine...the GFB valve i'm using works awsome (more responsive than stock) and i sware my car feels stronger now (i think the stokie was leaking alittle though) but yeah works fine...
i had used a turbosmart one in my car (the one with the trumpet) and i must say that it was an absolute peice of rubbish way to slow!!!comming off the throttle and jumping on again the valve would stay open to long and drive me nuts 
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Location:
cambo
Registered:
May 2002
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Re: Which BOV is the best
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Thu, 20 May 2004 10:48
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in regards to BOV operation off boost, wouldnt this only apply in those sequential type valves? i mean if its the piston type, wouldnt a vacuum infact help pull it closed? i thought only ones like the HKS SSQ worked on pressure variations?
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