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Dump valve


honda900rr
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Some cars like them... other cars don't, seem to be hit or miss whether the car doesn't care if you dump a whole load of air instead of recirculating it. I went for a variable one so I could choose how much dumps and how much recirculates to prevent lumpy gear changes... it's now 100% atmo since I had my remap.

I've got this one: (It will fit the standard WRX intercooler)

http://www.scoobyparts.com/performance/gfb-tuning-products/gfb-respons-tms-bov

IMG_20151206_142630.jpg

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Good question. I'm looking at fitting one in the spring. Looking at the GFB Respons that Sandals is running. Car will be getting remap after fitting so my questions: 

Are there any performance advantage to recirc or vent? Obviously more noise with a vent to atmosphere but is there performance loss despite tuning? Surely it's better to get rid of the hot air from the system rather than reintroduce it to the 'cold inlet'?

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4 minutes ago, DDoc said:

Good question. I'm looking at fitting one in the spring. Looking at the GFB Respons that Sandals is running. Car will be getting remap after fitting so my question is - is there any performance advantage to recirc or vent? Obviously more noise with a vent to atmosphere but is there performance loss despite tuning?

People claim an atmospheric one allows the turbo to come back on boost quicker n such but there doesn't seem to be any proof or noticeable difference. I just like the noise :D

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1 minute ago, Sandals said:

People claim an atmospheric one allows the turbo to come back on boost quicker n such but there doesn't seem to be any proof or noticeable difference. I just like the noise :D

Yeah I love the noise 👍 Cant see how there would be much difference on spooling time. Fundamentally doing the same thing which is releasing any back pressure on the turbo wheel to stop it 'slowing down' (allows it to continue spinning quickly therefore less lag when boost applied). Maybe someone with more knowledge will correct me. Guess vent to atmosphere might do it fractional quicker because there will be no back pressure in any hoses?? 

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9 minutes ago, DDoc said:

Yeah I love the noise 👍 Cant see how there would be much difference on spooling time. Fundamentally doing the same thing which is releasing any back pressure on the turbo wheel to stop it 'slowing down' (allows it to continue spinning quickly therefore less lag when boost applied). Maybe someone with more knowledge will correct me. Guess vent to atmosphere might do it fractional quicker because there will be no back pressure in any hoses?? 

According to the GFB blurb:

" Tests show that TMS features can return the engine to peak boost up to 30% faster than a factory diverter valve when shifting gears."

I would have thought 30% would have been noticeable but I certainly didn't feel any difference....

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1 hour ago, Scoobyghost said:

The arguement for which is better goes both ways. Recirc: pressure is already built up in the intake and the air has already been monitored by the sensors. Apart from some cars not liking them the biggest difference is one goes woosh the other doesn't

Yeah that makes sense also. Think if I get the GFB Respons I'll just go 50/50 😂 Can't go wrong that way. 

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Good question. I'm looking at fitting one in the spring. Looking at the GFB Respons that Sandals is running. Car will be getting remap after fitting so my questions: 

Are there any performance advantage to recirc or vent? Obviously more noise with a vent to atmosphere but is there performance loss despite tuning? Surely it's better to get rid of the hot air from the system rather than reintroduce it to the 'cold inlet'?

I have the gfb responce on my hatch fitted to my frontmount,if i have it fully vent to atmosphere then can feel the lag if you floor it,if i have it full recerc then i get the flutter noise from the turbo but car power is their straight away.on a top mount you wouldnt feel the diffrence as much as with frontmount lettin pressure out all that piping,i also had a gfb on a blob with top mount and car hated it just wouldnt run right so i went back to a oem sti recer valve with that and it made car 100% better.on the hatch i have it just open so its not very loud when venting and dont get back pressure and keeps enough pressure to stop lag.gfb is not a cheap blowoff valve but it is a good one just have to set it up to how car likes it and how you like the sound.

Sent from my LG-D855 using Tapatalk

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3 hours ago, aucky said:

I have the gfb responce on my hatch fitted to my frontmount,if i have it fully vent to atmosphere then can feel the lag if you floor it,if i have it full recerc then i get the flutter noise from the turbo but car power is their straight away.on a top mount you wouldnt feel the diffrence as much as with frontmount lettin pressure out all that piping,i also had a gfb on a blob with top mount and car hated it just wouldnt run right so i went back to a oem sti recer valve with that and it made car 100% better.on the hatch i have it just open so its not very loud when venting and dont get back pressure and keeps enough pressure to stop lag.gfb is not a cheap blowoff valve but it is a good one just have to set it up to how car likes it and how you like the sound.

Sent from my LG-D855 using Tapatalk

So running with your front mount you get better performance running it in full recirc...interesting. Was that the way it was when your car was mapped? Does your car still use a MAF sensor? I can see that the advantages are greater with a front mount as there will be more volume of trapped air in the longer pipework. Yeah it's not a cheap bit of kit...was hoping to pick up a second hand one but haven't seen one in the 6 months I've been looking so will probably end up buying it new. Where you get yours? Tarmac sportz? 

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The main claims of being faster and better are mainly due to the construction and materials used in the valves, the standard recirc on mine is a plastic diaphragm which is rubbish, the forge one is all ally construction and has better a spring instead of it operating on a crappy spindle.

So it's dumps faster and at a more controlled rate,

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2 hours ago, DDoc said:

So running with your front mount you get better performance running it in full recirc...interesting. Was that the way it was when your car was mapped? Does your car still use a MAF sensor? I can see that the advantages are greater with a front mount as there will be more volume of trapped air in the longer pipework. Yeah it's not a cheap bit of kit...was hoping to pick up a second hand one but haven't seen one in the 6 months I've been looking so will probably end up buying it new. Where you get yours? Tarmac sportz? 

that is correct, in full reserc then their is no lag as don't have the valve releasing all the pressure each time I change gear,their is about 2 1/2 metre of 3"inch pipe with a front mount so you want to keep pressure up,you really want to keep pressure up with a top mount also,thats why oem are reserc and not vent to atmosphere.vent to atmosphere are just to give you the silly woosh noise,their is no performance gains from having it,dont see rally teams venting to atmosphere,a dump valve is basically a safety valve nothing more just to keep pressure right but people I think firstly in japan started fitting vent atmosphere for shows and then everyone wanted the noise,your car is the wrx-s don't they have the big sti intercooler fitted to them,if so I wouldn't bother with a front mount unless your going 400bhp plus,your intercooler is good for 350bhp I read,my wrx topmount interccoler are tiny crap things,mine was already fitted to car when I got it but I can tell you if you do decide to go front mount,either get custom made so can have piping as short as possible and also don't buy the perrin or other other priced intercoolers as the cheaper eBay 1's do the job just as good and cost quarter the price.

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4 hours ago, aucky said:

that is correct, in full reserc then their is no lag as don't have the valve releasing all the pressure each time I change gear,their is about 2 1/2 metre of 3"inch pipe with a front mount so you want to keep pressure up,you really want to keep pressure up with a top mount also,thats why oem are reserc and not vent to atmosphere.vent to atmosphere are just to give you the silly woosh noise,their is no performance gains from having it,dont see rally teams venting to atmosphere,a dump valve is basically a safety valve nothing more just to keep pressure right but people I think firstly in japan started fitting vent atmosphere for shows and then everyone wanted the noise,your car is the wrx-s don't they have the big sti intercooler fitted to them,if so I wouldn't bother with a front mount unless your going 400bhp plus,your intercooler is good for 350bhp I read,my wrx topmount interccoler are tiny crap things,mine was already fitted to car when I got it but I can tell you if you do decide to go front mount,either get custom made so can have piping as short as possible and also don't buy the perrin or other other priced intercoolers as the cheaper ebay 1's do the job just as good and cost quarter the price.

I am still learning as I go along so please correct me if I'm wrong, but surely the idea of either method is to set the spring rate so that you release only just the right amount of air? Therefore (in theory of course) it shouldnt matter where the excess air actually goes? The amount of pressure released depends on how long the valve is open when the vacuum is created inside the manifold after the throttle is shut. Whether the section of pipe is 2m or 0.25m can you not adjust the time the valve is open to achieve the 'perfect' back pressure under hard boost? In a longer section of pipe the valve would need to be closed quicker to release less air and maintain the pressure? Where the excess air goes plays no part in maintaining pressure on the turbo side. 

Unfortunately not, WRXS still has a crappy small top mount. I won't be going front mount route. Not anytime soon anyway. Not looking at that kind of power...yet 😜 If anything I quite like the look of the process west verticooler. Not sure if it's a bit of a gimmick or not though. Plus it's !Removed! expensive. 

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17 minutes ago, DDoc said:

 

I am still learning as I go along so please correct me if I'm wrong, but surely the idea of either method is to set the spring rate so that you release only just the right amount of air? Therefore (in theory of course) it shouldnt matter where the excess air actually goes? The amount of pressure released depends on how long the valve is open when the vacuum is created inside the manifold after the throttle is shut. Whether the section of pipe is 2m or 0.25m can you not adjust the time the valve is open to achieve the 'perfect' back pressure under hard boost? In a longer section of pipe the valve would need to be closed quicker to release less air and maintain the pressure? Where the excess air goes plays no part in maintaining pressure on the turbo side. 

Unfortunately not, WRXS still has a crappy small top mount. I won't be going front mount route. Not anytime soon anyway. Not looking at that kind of power...yet 😜 If anything I quite like the look of the process west verticooler. Not sure if it's a bit of a gimmick or not though. Plus it's !Removed! expensive. 

were all still learning things mate and am no expert on them either just stuff I have read like this https://en.wikipedia.org/wiki/Blowoff_valve  and stuff I have been told or even watched on you tube.good choice that as if I was going to change back to a top mount I was going to go with a verticooler but puts me off having to import from America,so my plan was I was going to fab my own design one up and even maybe sell them,grimmspeed do a good top mount for the wrx and wrx-s as well,i follow a guy on youtube with the verticooler on a 400bhp wrx hatch so their good coolers,but we will see what I do when weather gets better and I can get back out side and get fabbin again :wink:oh and I forgot to say on my last post yes I still have the maf fitted on my car.so you have a turbo that bolts straight to the intercooler then like mine,do you no what turbo it is?

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13 hours ago, aucky said:

were all still learning things mate and am no expert on them either just stuff I have read like this https://en.wikipedia.org/wiki/Blowoff_valve  and stuff I have been told or even watched on you tube.good choice that as if I was going to change back to a top mount I was going to go with a verticooler but puts me off having to import from America,so my plan was I was going to fab my own design one up and even maybe sell them,grimmspeed do a good top mount for the wrx and wrx-s as well,i follow a guy on youtube with the verticooler on a 400bhp wrx hatch so their good coolers,but we will see what I do when weather gets better and I can get back out side and get fabbin again :wink:oh and I forgot to say on my last post yes I still have the maf fitted on my car.so you have a turbo that bolts straight to the intercooler then like mine,do you no what turbo it is?

IMG_1772.JPGKeep us posted on your fabrication activities then. Yeah my turbo is just bolted straight onto the inter cooler as far as I'm aware. I'm actually not to sure what turbo it is.  Been trying to find that out. Over in the states the 08 WRX runs a TD04 but got changed in 09 to a IHI VF52. Not 100% sure if that's the same in the UK. Pretty sure the WRX-S runs the same turbo as the standard WRX though. Not actually had a look at mine. Probably in spring when weather gets better. Might do the uppipe and downpipe. Not sure yet though. Anyone know if the hatchbacks have a carted uppipe? I hate that thought. 

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2 minutes ago, DDoc said:

Keep us posted on your fabrication activities then. Yeah my turbo is just bolted straight onto the inter cooler as far as I'm aware. I'm actually not to sure what turbo it is.  Been trying to find that out. Over in the states the 08 WRX runs a TD04 but got changed in 09 to a IHI VF52. Not 100% sure if that's the same in the UK. Pretty sure the WRX-S runs the same turbo as the standard WRX though. Not actually had a look at mine. Probably in spring when weather gets better. Might do the uppipe and downpipe. Not sure yet though. Anyone know if the hatchbacks have a carted uppipe? I hate that thought. 

I think they ditched the cat in the up-pipe all together after the Blob...

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1 hour ago, DDoc said:

Keep us posted on your fabrication activities then. Yeah my turbo is just bolted straight onto the inter cooler as far as I'm aware. I'm actually not to sure what turbo it is.  Been trying to find that out. Over in the states the 08 WRX runs a TD04 but got changed in 09 to a IHI VF52. Not 100% sure if that's the same in the UK. Pretty sure the WRX-S runs the same turbo as the standard WRX though. Not actually had a look at mine. Probably in spring when weather gets better. Might do the uppipe and downpipe. Not sure yet though. Anyone know if the hatchbacks have a carted uppipe? I hate that thought. 

yeah that what I had read and my wrx has been upgraded to a vf52 so was wondering if it had come from a uk wrx-s or had been inported from states or something.those intercoolers are pretty crap,remember first time I removed my top mount I nearly pulled end off when I was wrestling it off throttle body hose,have to be fairly gentle with them.

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