dump valve yes or no
30 November 2009, 09:53 PM
#2
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Leave it on!! It is there to prevent damage to the turbo when you close the throttle by getting rid of any boost pressure whilst the turbo is at speed.
30 November 2009, 10:03 PM
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its one that has been put on by the previous owner....to be honest i dont mind it but i like the sount of the chatter that the air filter gives off but when the dump valve kicks in the chatter dont happen that was my reason for asking as i would have taken it off
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01 December 2009, 05:30 PM
#15
well if you have the standard one ill have it off you for a bailey dump valve, fitted to my 2002 bugeye, like my car quiet for the journey to work every day, thats why i changed my loud 5" exhaust to an sti one. so if anybody has a standard one they wanna swap for mine, please say x or just send it to me(ask for address)
02 December 2009, 01:16 PM
#17
Are they not called chav horns these days?Most of the muppets round my way have'nt got a clue what they do,just love the irritating noise they give when driving round & round & round town.No wonder there are so many haters out there for scoob drivers.
02 December 2009, 02:49 PM
#21
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In some cases dump valves can cause engines to run to rich this can put to much fuel into the cylinder head we all know petrol is a natral degreaser and the the excess fuel washes out the lubrication inthe cylinder head and cause higher temps and lead to premature wear.
02 December 2009, 02:50 PM
#22
The Impreza already HAS a dumpvalve, it's a recirculating type, so puts the dumped compressed air back into the intake. It's therefore a bit quieter than a VTA, (vent to atmosphere), one.
The MAF, (mass air flow meter), on the car meters the intake air passing it, before it's compressed, and the ecu adjusts fuelling accordingly. The standard recirc dumpvalve has no effect on this, since it just puts the SAME metered air back in to be recompressed.
The VTA d/v, however, allows a LOT of pre-metered air to escape, but the ecu STILL fuels for it, so producing a VERY rich mixture. The excess fuel in this mixture can cause the oil to be "washed" off the bores. That's borewash, and it produces premature wear in the bores, which can lead to engine failure.
A VTA d/v also produces pops and bangs in the exhaust and cat due to over-fuelling, this can burn exhaust valves, burn exhausts, destroy the cat, etc.
Think about it: if there was ANYTHING to be gained from fitting a VTA d/v, Subaru, or Prodrive, would do it. They don't. End of
The MAF, (mass air flow meter), on the car meters the intake air passing it, before it's compressed, and the ecu adjusts fuelling accordingly. The standard recirc dumpvalve has no effect on this, since it just puts the SAME metered air back in to be recompressed.
The VTA d/v, however, allows a LOT of pre-metered air to escape, but the ecu STILL fuels for it, so producing a VERY rich mixture. The excess fuel in this mixture can cause the oil to be "washed" off the bores. That's borewash, and it produces premature wear in the bores, which can lead to engine failure.
A VTA d/v also produces pops and bangs in the exhaust and cat due to over-fuelling, this can burn exhaust valves, burn exhausts, destroy the cat, etc.
Think about it: if there was ANYTHING to be gained from fitting a VTA d/v, Subaru, or Prodrive, would do it. They don't. End of
02 December 2009, 02:54 PM
#23
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get rid your car will still dump through the induction kit it sounds 10 times better than, i have been without dv for nearly 2 years no problems with turbo at all
02 December 2009, 02:55 PM
#24
When a VTA BOV dumps the air from your intercooler you get a rich state in the cylinders in between gearchanges. Running very rich results in excess fuel washing the cylinder bores of lubrication hence the term Borewash. Not good. Also, cars with a VTA BOV/Dump Valve tend to suffer from a very agressive jerk on gearchange which can result in jerking passengers heads forward violently which is just plain horrible!!
A recirculating air Bypass Valve dumps the air back into the turbo inlet pipe thereby avoiding a rich state between gear changes. No violent head jerking either.
In most cases your car will run more smoothly with the standard Air Bypass Valve fitted which is good till well past 400bhp.
Aftermarket BOV's/Dump Valves end up being a pain on standard or mildly modified scoobs. Unless you're making really decent power and you run an FMIC don't bother.
Edited to add....I'm obviously running to slow today so what everyone else said
A recirculating air Bypass Valve dumps the air back into the turbo inlet pipe thereby avoiding a rich state between gear changes. No violent head jerking either.
In most cases your car will run more smoothly with the standard Air Bypass Valve fitted which is good till well past 400bhp.
Aftermarket BOV's/Dump Valves end up being a pain on standard or mildly modified scoobs. Unless you're making really decent power and you run an FMIC don't bother.
Edited to add....I'm obviously running to slow today so what everyone else said
Last edited by scoobiewrx555; 02 December 2009 at 02:56 PM.
02 December 2009, 07:25 PM
#28
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Mine runs fine, and compared to the amount of fuel chucked in to make it go faster..... how is a second of "farting" metered air going to affect anything ?
I also have the stiffest spring fitted to mine to avoid urban embarassment, so it ONLY operates at over 4000 rpm and > 1.6 bar of boost.
So, you choose ?
dunx
P.S. Subaru make cars to last 100,000 miles, we make them last half as long but twice as fast....
I also have the stiffest spring fitted to mine to avoid urban embarassment, so it ONLY operates at over 4000 rpm and > 1.6 bar of boost.
So, you choose ?
dunx
P.S. Subaru make cars to last 100,000 miles, we make them last half as long but twice as fast....
Last edited by dunx; 02 December 2009 at 07:27 PM.
02 December 2009, 08:09 PM
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Been running without a dump valve for 8 months now without problem. Car runs better without, no noticeable effect on spool up (feels better if i'm honest). Turbo stall sounds mental, far better than any dump valve 
.
.
02 December 2009, 08:15 PM
#30
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Ive always thought of totally blocking the bov on my 99 turbo, currently running a TD05 16G, FMIC, etc, all mapped by Zen @337bhp,
The last couple of years ive had an hks bov on it (which i personally love), but after going out in T7rst's RB5 with the bov totally blocked off ive been starting to reconsider, (that fluttering sound is nuts)
Would running no dump valve at all affect my car in any way-with the set up i have?
The last couple of years ive had an hks bov on it (which i personally love), but after going out in T7rst's RB5 with the bov totally blocked off ive been starting to reconsider, (that fluttering sound is nuts)
Would running no dump valve at all affect my car in any way-with the set up i have?