dump valve or bov !!! whats your choice??
Not wanting to harp on ,but i have had 5 different dv's in the last 2 years and dispite what the manufactures claim, not 1 of them has improved the performance of my car.
In laymens terms: Why did subaru fit a MAF sensor to the car and what was it s purpose ?? It is to measure the air that is being passed through the sensor and allows the ecu to calculate the fuelling. When the car vents the air to atmosphere the ecu has accounted for that air,which is no longer there;,so the ecu compensates with more fuel,which is why you can get the pops and bangs sometimes associated when running a dv. Also the air that is normally recirculated back into the inlet tract aids the the pressure on the compressor side of the turbo,so when it vents to air you loose a little bit of pressure,which can mommentarily hinder the spool up .
The cars that run bov's proffesionally are not just bolted on ,they are normally mapped in to the running of the car ,so with that in mind. you make your own mind up. I did ,but not by reading what people said on a web site ,but by trial & error after using a baileys,forge,gfb,turbosmart ,&finally a blitz.All of them made a noise,but none made the car run any smoother than when the std recirc was fitted- Fact
Can we now have a poll on how long before the next dumpvalve thread comes up ,I will start with : 1 week lol
In laymens terms: Why did subaru fit a MAF sensor to the car and what was it s purpose ?? It is to measure the air that is being passed through the sensor and allows the ecu to calculate the fuelling. When the car vents the air to atmosphere the ecu has accounted for that air,which is no longer there;,so the ecu compensates with more fuel,which is why you can get the pops and bangs sometimes associated when running a dv. Also the air that is normally recirculated back into the inlet tract aids the the pressure on the compressor side of the turbo,so when it vents to air you loose a little bit of pressure,which can mommentarily hinder the spool up .
The cars that run bov's proffesionally are not just bolted on ,they are normally mapped in to the running of the car ,so with that in mind. you make your own mind up. I did ,but not by reading what people said on a web site ,but by trial & error after using a baileys,forge,gfb,turbosmart ,&finally a blitz.All of them made a noise,but none made the car run any smoother than when the std recirc was fitted- Fact
Can we now have a poll on how long before the next dumpvalve thread comes up ,I will start with : 1 week lol
Last edited by midnight; Sep 18, 2011 at 06:55 AM.
Scooby Regular
Joined: Sep 2011
Posts: 1,041
Likes: 0
From: Ipswich
I hear what your saying about "another bov thread" but for people like me (scoobynet member for less than 2 weeks) it is a good read on what people have done and there experiences. Because to be honest I can't be arsed to search just yet to find out about bov. That is because there are so many new threads I am reading and am learning so much. So for that a massive thanks to everyone.
But I do get very confused sometimes and now is one of those times. Sounds like I need to get rid of the baylies I have fitted, bought car with it on, and go for a forge recurc.
No dought some will agree and some will disagree, but at the end of the day we are all different and that is what makes us who we are, and our scooby's what they are.
I like the phfffftt and just want a better one, if that makes me a 37 year old chav, then so be it!!
But I do get very confused sometimes and now is one of those times. Sounds like I need to get rid of the baylies I have fitted, bought car with it on, and go for a forge recurc.
No dought some will agree and some will disagree, but at the end of the day we are all different and that is what makes us who we are, and our scooby's what they are.
I like the phfffftt and just want a better one, if that makes me a 37 year old chav, then so be it!!
"Why did subaru fit a MAF sensor to the car and what was it s purpose ?? It is to measure the air that is being passed through the sensor and allows the ecu to calculate the fuelling. When the car vents the air to atmosphere the ecu has accounted for that air,which is no longer there"
yarp!
"so the ecu compensates with more fuel,which is why you can get the pops and bangs sometimes associated when running a dv."
Not really, the ecu puts in the right amount of fuel for the air which has passed the maf, but some of the air has escaped, therefore there a surplus of fuel.
"Also the air that is normally recirculated back into the inlet tract aids the the pressure on the compressor side of the turbo,so when it vents to air you loose a little bit of pressure,which can mommentarily hinder the spool up"
No, the inlet tract on the air filter side of the turbo has negligable pressure .... in fact its occasionally a vacuum if the turbo is pulling more air in than the air filter can pass. But dont read anything into this as it isnt a performance gain in any way, the oem system of dumping to between the maf and the turbo is for-
-so as not to have to fit a smaller maf on the outlet of the dump valve to measure escaped air to subtract from the normal mafs reading.
-Alot of the noise is hidden by the resonator and filter boxes.
"The cars that run bov's proffesionally are not just bolted on ,they are normally mapped in to the running of the car"
Yes, probably always running with wideband lambda and map (manifold air pressure) sensors to do the job of the maf!
Alot of chavs go for the atmospherics because of the noise, but your right, until you get into the associated mods of much higher power figures than chavs can afford there are many more reasons against than for!
"Can we now have a poll on how long before the next dumpvalve thread comes up ,I will start with : 1 week lol"
A week sounds about right! but least pinging a link to this thread at them will be easyer than trying to explain it all again!
yarp!
"so the ecu compensates with more fuel,which is why you can get the pops and bangs sometimes associated when running a dv."
Not really, the ecu puts in the right amount of fuel for the air which has passed the maf, but some of the air has escaped, therefore there a surplus of fuel.
"Also the air that is normally recirculated back into the inlet tract aids the the pressure on the compressor side of the turbo,so when it vents to air you loose a little bit of pressure,which can mommentarily hinder the spool up"
No, the inlet tract on the air filter side of the turbo has negligable pressure .... in fact its occasionally a vacuum if the turbo is pulling more air in than the air filter can pass. But dont read anything into this as it isnt a performance gain in any way, the oem system of dumping to between the maf and the turbo is for-
-so as not to have to fit a smaller maf on the outlet of the dump valve to measure escaped air to subtract from the normal mafs reading.
-Alot of the noise is hidden by the resonator and filter boxes.
"The cars that run bov's proffesionally are not just bolted on ,they are normally mapped in to the running of the car"
Yes, probably always running with wideband lambda and map (manifold air pressure) sensors to do the job of the maf!
Alot of chavs go for the atmospherics because of the noise, but your right, until you get into the associated mods of much higher power figures than chavs can afford there are many more reasons against than for!
"Can we now have a poll on how long before the next dumpvalve thread comes up ,I will start with : 1 week lol"
A week sounds about right! but least pinging a link to this thread at them will be easyer than trying to explain it all again!
"Why did subaru fit a MAF sensor to the car and what was it s purpose ?? It is to measure the air that is being passed through the sensor and allows the ecu to calculate the fuelling. When the car vents the air to atmosphere the ecu has accounted for that air,which is no longer there"
yarp!
"so the ecu compensates with more fuel,which is why you can get the pops and bangs sometimes associated when running a dv."
Not really, the ecu puts in the right amount of fuel for the air which has passed the maf, but some of the air has escaped, therefore there a surplus of fuel.
el"Also the air that is normally recirculated back into the inlet tract aids the the pressure on the compressor side of the turbo,so when it vents to air you loose a little bit of pressure,which can mommentarily hinder the spool up"
No, the inlet tract on the air filter side of the turbo has negligable pressure .... in fact its occasionally a vacuum if the turbo is pulling more air in than the air filter can pass. But dont read anything into this as it isnt a performance gain in any way, the oem system of dumping to between the maf and the turbo is for-
-so as not to have to fit a smaller maf on the outlet of the dump valve to measure escaped air to subtract from the normal mafs reading.
-Alot of the noise is hidden by the resonator and filter boxes.
"The cars that run bov's proffesionally are not just bolted on ,they are normally mapped in to the running of the car"
Yes, probably always running with wideband lambda and map (manifold air pressure) sensors to do the job of the maf!
Alot of chavs go for the atmospherics because of the noise, but your right, until you get into the associated mods of much higher power figures than chavs can afford there are many more reasons against than for!
"Can we now have a poll on how long before the next dumpvalve thread comes up ,I will start with : 1 week lol"
A week sounds about right! but least pinging a link to this thread at them will be easyer than trying to explain it all again!
yarp!
"so the ecu compensates with more fuel,which is why you can get the pops and bangs sometimes associated when running a dv."
Not really, the ecu puts in the right amount of fuel for the air which has passed the maf, but some of the air has escaped, therefore there a surplus of fuel.
el"Also the air that is normally recirculated back into the inlet tract aids the the pressure on the compressor side of the turbo,so when it vents to air you loose a little bit of pressure,which can mommentarily hinder the spool up"
No, the inlet tract on the air filter side of the turbo has negligable pressure .... in fact its occasionally a vacuum if the turbo is pulling more air in than the air filter can pass. But dont read anything into this as it isnt a performance gain in any way, the oem system of dumping to between the maf and the turbo is for-
-so as not to have to fit a smaller maf on the outlet of the dump valve to measure escaped air to subtract from the normal mafs reading.
-Alot of the noise is hidden by the resonator and filter boxes.
"The cars that run bov's proffesionally are not just bolted on ,they are normally mapped in to the running of the car"
Yes, probably always running with wideband lambda and map (manifold air pressure) sensors to do the job of the maf!
Alot of chavs go for the atmospherics because of the noise, but your right, until you get into the associated mods of much higher power figures than chavs can afford there are many more reasons against than for!
"Can we now have a poll on how long before the next dumpvalve thread comes up ,I will start with : 1 week lol"
A week sounds about right! but least pinging a link to this thread at them will be easyer than trying to explain it all again!
Scooby Newbie
Joined: Sep 2011
Posts: 9
Likes: 0
From: carmarthenshire
Only having been a member for few hours, it is amazing the input my thread has invited, although there there are mixed feelings regardibg BOV's, so I am going to take onboard the advice to leave well alone and air on the side of caution, it has taken me long enough to own a scooby and I ain't about to take the chance of having my dream turn into a nightmare.
Thanks once again for the constructive advice, and any other issues I need advice on I will defo post another thread, cheers or as we say in wales Hwyl !
Thanks once again for the constructive advice, and any other issues I need advice on I will defo post another thread, cheers or as we say in wales Hwyl !
If you want to fit a 'noisy' VTA BOV/DV (same thing) and get mapped (invaraibly with other mods for a bhp increase), then no worries - as all fuelling should be accounted for in the remap.
I like 'em. Not because of the noise, but instead knowing the back pressure on the turbo's impeller is being relieved as much as possible on throttle-closes, thus potentially increasing the turbo's longevity.
Just don't fit a Bailey's - for some reason the EJ motor, allegedly, doesn't 'like' 'em.
I have a big API-supplied piston-type one (no worry of it being able to remain closed if running big boost i.e. won't gradually creep open, thus not leaking boost) -- it looks remarkably like a GFB (the Aussie company, Go Faster Bits) type design. It's great, as it only opens fully/makes a noise at high boost pressure throttle-closes. Non-hooning driving, it's as silent as a lamb.
And the only reason I have a VTA one is because of this reason...
...BUT... I ideally wanted to reuse the OEM recirc MY99/00 one (by using one of harvey's MY99 flange adaptors). But, unfortunately, my Hyperflow's FMIC pipework dictated otherwise i.e. the OEM DV's recirc couldn't be easlily re-routed back to the turbo intake. Hence why I have just a good quality VTA type fitted.
So please don't label me a "Maccy D's car park-frequenting/teen girl-bothering/pfssssst-based chav" lol
I like 'em. Not because of the noise, but instead knowing the back pressure on the turbo's impeller is being relieved as much as possible on throttle-closes, thus potentially increasing the turbo's longevity.
Just don't fit a Bailey's - for some reason the EJ motor, allegedly, doesn't 'like' 'em.
I have a big API-supplied piston-type one (no worry of it being able to remain closed if running big boost i.e. won't gradually creep open, thus not leaking boost) -- it looks remarkably like a GFB (the Aussie company, Go Faster Bits) type design. It's great, as it only opens fully/makes a noise at high boost pressure throttle-closes. Non-hooning driving, it's as silent as a lamb.
And the only reason I have a VTA one is because of this reason...
...BUT... I ideally wanted to reuse the OEM recirc MY99/00 one (by using one of harvey's MY99 flange adaptors). But, unfortunately, my Hyperflow's FMIC pipework dictated otherwise i.e. the OEM DV's recirc couldn't be easlily re-routed back to the turbo intake. Hence why I have just a good quality VTA type fitted.
So please don't label me a "Maccy D's car park-frequenting/teen girl-bothering/pfssssst-based chav" lol
Last edited by joz8968; Sep 18, 2011 at 03:22 PM.
It's the over-fuelling and bore wash issues you can get with VTA dump valves (BOV or whatever) that would concern me. Stick to the Subaru re-circulating one and you'll have none of these issues.
Unless of course your sole objective in life is to make the teenage girls who hang around the Maccy D's car park on an evening go a bit moist over your Scooby-Do
Unless of course your sole objective in life is to make the teenage girls who hang around the Maccy D's car park on an evening go a bit moist over your Scooby-Do
Scooby Regular
Joined: Nov 2010
Posts: 481
Likes: 0
From: bath/Bristol area
i always have a HKS as i find the baileys tend to stick sometimes on boost , forge or blitz are also quite good but for the quality andd sound i deffeintly would get Hks sqv for the chirp noise =]
Seeing as this thread has been resurrected like hell lol...
I have indeed since replaced my VTA with a Forge MY97/98-pattern recirc jobbie. Idle is so much better/nicer - it's now rock solid. And I'm convinced car runs nicer overall e.g. throttle response seems sharper, etc. (but that could just be Placebo, of course...)
I have indeed since replaced my VTA with a Forge MY97/98-pattern recirc jobbie. Idle is so much better/nicer - it's now rock solid. And I'm convinced car runs nicer overall e.g. throttle response seems sharper, etc. (but that could just be Placebo, of course...)
Last edited by joz8968; Apr 21, 2012 at 09:22 PM.
Scooby Regular
Joined: Apr 2010
Posts: 644
Likes: 0
From: Dublin,Ireland
This. All the nay sayers say to the likes of me and Jeff where's the proof of engines blowing up etc. but I haven't seen any proof of VTA BOV's giving any performance gains in bhp?
Scooby Regular
Joined: Sep 2007
Posts: 1,438
Likes: 0
Just removed the adjustable dump valve from my 05 sti blob last week there and fitted a standard re-circulating one. There was nothing wrong with the dump valve and its working perfectly but i just cant believe how much better the car drives now without it, just so much smoother and sweeter, should have got rid of it ages ago....
Looks like we have saved another Scooby from going POP and a new owner who has seen the light and realised people would just laugh as he was going ppppsssssttttt along the road