View Poll Results: Does a D/V make a difference?
Improves performance
6
18.75%
Detracts from performance
9
28.13%
No difference
17
53.13%
Voters: 32. You may not vote on this poll
Do Dump Valves Have Any Real Benefit?
03 July 2005, 08:45 PM
#31
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I used to have a baileys d/v in my old car, I put it on, at first I loved it (didnt notice any performance benefit, although as the turbo spools up the sound together with an induction kit is nice) but after a while you start noticing chavs with d/vs on their cars! but mostly its SO IRRITATING!! Especially the baileys which leaks air at high constant speeds so it sounds like youve got a pissed of serpent in ur engine bay!! It would be great if you could turn it on and off to your liking!! I wouldnt have it again....theres no point or gains.
03 July 2005, 11:01 PM
#32
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Originally Posted by 05WRX
Firstly, by DV - I assume you mean Diverter Valve (or as mostly referred to by Brits a Dump Valve).
All modern turbo engines use them. They protect the turbo.
Their purpose is to exit boost pressure either into the airbox or into the atmosphere when the throttle plate shuts quickly. This is to prevent the created back pressure shockwave damaging the turbo.
There are two main types of DV.
Recirculating DV or Atmospheric DV. Both do the same job... to protect your turbo.
They do not add any more performance, unless the new one replaced one that was faulty.
DVs come in different flavours.
Some Recirculating Ones(usually OEM Bosch ones) are made of plastic and use a rubber diaphragm to divert air pressure. These commonly fail on cars and causes the air system to be in a constantly diverted state, which leads to low boost.
Aftermarket DVs are generally built of billet aluminum and usually use a piston and spring method to divert air pressure. These are more reliable because they don't use a fragile rubber diaphragm - but they are more expensive.
Their resistance to opening can be tuned with different springs, so if you're running a lot of boost, you can tweek them so that they hold that boost before opening.
Atmospheric DVs are usually constructed in a similar way to a recirculating DV but instead of venting to the airbox, they merely vent to air. They use a twin piston arrangement normally to allow the car to idle properly.
I'd always chose a good aftermarket piston DV over an OEM diaphragm DV, cos it's one less thing that usually goes wrong in a turbo system. However, you'll need to remember to regularly lubricate the piston, otherwise it will stick.
Comparisons between Atmospheric DVs and Recirculating DVs?
Cars that use MAFs get a little upset with Atmospheric DVs. These dump, pre-metered combustible air when the throttle-plate closes, which means the ECU has mapped a certain amount of fuel for that cycle. But with that air not there, the car is running incredibly rich for that moment, dumping unburned fuel into a very hot CAT and exhaust, which of-course ignites, causing longer term damage to the ceramic cores.
Aftermarket Recirculating DVs are installed the same way as the OEM one, and just divert the pre-metered air. The air isn't lost, so fueling remains correct.
Atmospheric DVs make more noise than Recirculating DVs. Unless the noise snorkel on the intake is messed with, or you're running an open-air cold feed kit.
So yes, you're car does work better with a DV than without. But probably better with a recirculating DV than an atmospheric DV.
All modern turbo engines use them. They protect the turbo.
Their purpose is to exit boost pressure either into the airbox or into the atmosphere when the throttle plate shuts quickly. This is to prevent the created back pressure shockwave damaging the turbo.
There are two main types of DV.
Recirculating DV or Atmospheric DV. Both do the same job... to protect your turbo.
They do not add any more performance, unless the new one replaced one that was faulty.
DVs come in different flavours.
Some Recirculating Ones(usually OEM Bosch ones) are made of plastic and use a rubber diaphragm to divert air pressure. These commonly fail on cars and causes the air system to be in a constantly diverted state, which leads to low boost.
Aftermarket DVs are generally built of billet aluminum and usually use a piston and spring method to divert air pressure. These are more reliable because they don't use a fragile rubber diaphragm - but they are more expensive.
Their resistance to opening can be tuned with different springs, so if you're running a lot of boost, you can tweek them so that they hold that boost before opening.
Atmospheric DVs are usually constructed in a similar way to a recirculating DV but instead of venting to the airbox, they merely vent to air. They use a twin piston arrangement normally to allow the car to idle properly.
I'd always chose a good aftermarket piston DV over an OEM diaphragm DV, cos it's one less thing that usually goes wrong in a turbo system. However, you'll need to remember to regularly lubricate the piston, otherwise it will stick.
Comparisons between Atmospheric DVs and Recirculating DVs?
Cars that use MAFs get a little upset with Atmospheric DVs. These dump, pre-metered combustible air when the throttle-plate closes, which means the ECU has mapped a certain amount of fuel for that cycle. But with that air not there, the car is running incredibly rich for that moment, dumping unburned fuel into a very hot CAT and exhaust, which of-course ignites, causing longer term damage to the ceramic cores.
Aftermarket Recirculating DVs are installed the same way as the OEM one, and just divert the pre-metered air. The air isn't lost, so fueling remains correct.
Atmospheric DVs make more noise than Recirculating DVs. Unless the noise snorkel on the intake is messed with, or you're running an open-air cold feed kit.
So yes, you're car does work better with a DV than without. But probably better with a recirculating DV than an atmospheric DV.
Soo the VTA D/V can damage your cats, lucky i havent got any then
Cookie
03 July 2005, 11:36 PM
#33
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Its best to have a DV atmos or recirc because it stops that back lash in gear changes, its annoying when racing through gears and you get that 1 second initial lag, least with a uprated DV the turbo dont get a bacl lash and continues to spin so when you belt your foot back on the accelerator the boost is there straight away, not the 1 second lag delay.
Im having difficulty cos my99 was remapped without filter or upreated DV therefore after ive tried adding one and a filter, it messes up and drives like a fiat 126, so im gonna try the recirculating DV and if failing that, ill add an atmos DV and Filter then have it adjusted on my remap!!!!!
Im having difficulty cos my99 was remapped without filter or upreated DV therefore after ive tried adding one and a filter, it messes up and drives like a fiat 126, so im gonna try the recirculating DV and if failing that, ill add an atmos DV and Filter then have it adjusted on my remap!!!!!
03 July 2005, 11:56 PM
#34
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Originally Posted by 05WRX
Firstly, by DV - I assume you mean Diverter Valve (or as mostly referred to by Brits a Dump Valve).
All modern turbo engines use them. They protect the turbo.
Their purpose is to exit boost pressure either into the airbox or into the atmosphere when the throttle plate shuts quickly. This is to prevent the created back pressure shockwave damaging the turbo.
There are two main types of DV.
Recirculating DV or Atmospheric DV. Both do the same job... to protect your turbo.
They do not add any more performance, unless the new one replaced one that was faulty.
DVs come in different flavours.
Some Recirculating Ones(usually OEM Bosch ones) are made of plastic and use a rubber diaphragm to divert air pressure. These commonly fail on cars and causes the air system to be in a constantly diverted state, which leads to low boost.
Aftermarket DVs are generally built of billet aluminum and usually use a piston and spring method to divert air pressure. These are more reliable because they don't use a fragile rubber diaphragm - but they are more expensive.
Their resistance to opening can be tuned with different springs, so if you're running a lot of boost, you can tweek them so that they hold that boost before opening.
Atmospheric DVs are usually constructed in a similar way to a recirculating DV but instead of venting to the airbox, they merely vent to air. They use a twin piston arrangement normally to allow the car to idle properly.
I'd always chose a good aftermarket piston DV over an OEM diaphragm DV, cos it's one less thing that usually goes wrong in a turbo system. However, you'll need to remember to regularly lubricate the piston, otherwise it will stick.
Comparisons between Atmospheric DVs and Recirculating DVs?
Cars that use MAFs get a little upset with Atmospheric DVs. These dump, pre-metered combustible air when the throttle-plate closes, which means the ECU has mapped a certain amount of fuel for that cycle. But with that air not there, the car is running incredibly rich for that moment, dumping unburned fuel into a very hot CAT and exhaust, which of-course ignites, causing longer term damage to the ceramic cores.
Aftermarket Recirculating DVs are installed the same way as the OEM one, and just divert the pre-metered air. The air isn't lost, so fueling remains correct.
Atmospheric DVs make more noise than Recirculating DVs. Unless the noise snorkel on the intake is messed with, or you're running an open-air cold feed kit.
So yes, you're car does work better with a DV than without. But probably better with a recirculating DV than an atmospheric DV.
All modern turbo engines use them. They protect the turbo.
Their purpose is to exit boost pressure either into the airbox or into the atmosphere when the throttle plate shuts quickly. This is to prevent the created back pressure shockwave damaging the turbo.
There are two main types of DV.
Recirculating DV or Atmospheric DV. Both do the same job... to protect your turbo.
They do not add any more performance, unless the new one replaced one that was faulty.
DVs come in different flavours.
Some Recirculating Ones(usually OEM Bosch ones) are made of plastic and use a rubber diaphragm to divert air pressure. These commonly fail on cars and causes the air system to be in a constantly diverted state, which leads to low boost.
Aftermarket DVs are generally built of billet aluminum and usually use a piston and spring method to divert air pressure. These are more reliable because they don't use a fragile rubber diaphragm - but they are more expensive.
Their resistance to opening can be tuned with different springs, so if you're running a lot of boost, you can tweek them so that they hold that boost before opening.
Atmospheric DVs are usually constructed in a similar way to a recirculating DV but instead of venting to the airbox, they merely vent to air. They use a twin piston arrangement normally to allow the car to idle properly.
I'd always chose a good aftermarket piston DV over an OEM diaphragm DV, cos it's one less thing that usually goes wrong in a turbo system. However, you'll need to remember to regularly lubricate the piston, otherwise it will stick.
Comparisons between Atmospheric DVs and Recirculating DVs?
Cars that use MAFs get a little upset with Atmospheric DVs. These dump, pre-metered combustible air when the throttle-plate closes, which means the ECU has mapped a certain amount of fuel for that cycle. But with that air not there, the car is running incredibly rich for that moment, dumping unburned fuel into a very hot CAT and exhaust, which of-course ignites, causing longer term damage to the ceramic cores.
Aftermarket Recirculating DVs are installed the same way as the OEM one, and just divert the pre-metered air. The air isn't lost, so fueling remains correct.
Atmospheric DVs make more noise than Recirculating DVs. Unless the noise snorkel on the intake is messed with, or you're running an open-air cold feed kit.
So yes, you're car does work better with a DV than without. But probably better with a recirculating DV than an atmospheric DV.
Also, having the MY00 (apparently the MAF can cause problems), means a recirc DV is definitely the way to go then?
Last edited by bzz; 04 July 2005 at 12:01 AM.
04 July 2005, 12:10 AM
#35
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Originally Posted by bzz
At last - a real, well-explained answer!! Thanx mate, this is what I needed to know. Am I to understand that all Scooby's come factory fitted with a DV then? Was under the impression that people add them later......
Also, having the MY00 (apparently the MAF can cause problems), means a recirc DV is definitely the way to go then?
Also, having the MY00 (apparently the MAF can cause problems), means a recirc DV is definitely the way to go then?
COOSTAR waits to be corrected
04 July 2005, 09:23 AM
#36
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Originally Posted by cookstar
AFAIK all scoobies where fitted with d/v the only reason you may think they do not have one is because of the re-circulating type make very little tshhhh noise.
COOSTAR waits to be corrected
COOSTAR waits to be corrected
eg: does PPP make a difference, perhaps in the pressure being built up by the turbo. Whenever I drove a standard WRX in the past I never heard the noise.
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