Or do they just sound good?

I've never wanted one in PTMW! as although the sound of a Noble M12 popping and dumping 10 inches from your ear is aural orgasm, I don't think it'd do much for me on a daily basis.

My POV obviously but brought home when the Essex Convoy turned up @ Brands & I'd just been chatting to one of the XTR crews.

As the lovely rumble of scoobs (can we coin that as a scoob gathering? "Rumble of Scoobs"? ) came along the back of the stand, they looked up, then with a popping and a dumping of DVs, they laughed & said - "That'll help them get out of the gravel trap!"

They obviously considered it more of a Max Power addition than a serious performance aid.

Were they right?

 

yes

there gay and crap and should be locked in a cupboard with lexus lights and flamer kits

 

Dunno really, But when the vacuum hose broke off my OE dump valve there was a noticable diference in response between gear-changes.


whichs remind me, I need to adjust the spring on my dump valve...anyone know what pressure/vacuum it should start opening?

 

BTW...proper re-circ type before I get branded by the flame throwers

 

All the things I've read on the subject seem to indicate that the OEM part is about as good as they come performance wise.

The only reason I can see for changing them is if you want the noise from a VTA type rather than a recirc.

I wouldn't go so far as to say they were gay. . . . perhaps just a little camp though

 

I have personally spoken to many tuners almost all of the Cossie variety but they all say the same thing, they do NOWT for performance if anything they make it worse!

and it certainly did on my STi8, so its in the garage, wanna buy it? it even has a volumn control no really it does!

 

Dump valves ?

You should count yourself lucky that the standard Scooby one is ok. The VAG (Bosch) one plastic and they break fairly regularly unless you swap for a (sensible - Bailey/Forge) aftermarket one.

Allegedly keeps things on the boil more when changing gears, but not the reason I got mine !

 

Errr, My scoob Dump valve IS plastic...And It broke!!

Mind, I have a feeling it was a heavy handed mechanic at the main dealers when it was in for some work not long after I bought it. They bodged-fixed it by using some brake pipe and superglue My intercooler fins also got bent too...nothing to do with it being used as a tool tray like an other scoob I saw in the workshop [img]images/smilies/mad.gif[/img]

 

PTMW ... They do nothing for performance .... and they DO NOT sound good!! (IMO )

Gary

 

OK, if they do NOTHING for performace... so why did I notice a delay in response between gear changes when mine broke (permanently shut) At the time I had no knowledge of it being broke either - ruling out placebo etc etc.

[Edited by ALi-B - 11/11/2003 11:59:28 PM]

 

Becauase if it was stuck shut, the turbo air has nowhere to go, and back pressure the turbo, which slows / stops it. So, when you put your foot down, the combustion gas has to then get the turbo spinning again, hence the delay.

If it was working ok, you wouldnt notice the hesitation

People are talking about aftermarket atmospheric DV's in this thread.

MB

 

I love em!!! go and get one on PTMW. I'm off to play in the scoob........PSHHHHH!!!!!!!

 

Mark, this is not how a centri blower works. When the discharge route is closed, the discharge pressure reaches maximum for the compressor speed and airflow stops, as no air is being moved, no work is being done and the wheel spins down due to friction only, therfore a dump valve that is open too long will actually spin down a turbo quicker.

However as the throttle is closed, the compression in the mass of moving air causes a pressure wave to travel back up the inlet and into the turbo. This reverse flow will impinge on the compressor wheel and can slow it or stall it and even cause the wheel to fail. The dump valve vents this reverse flow and ideally should then snap shut after its gone.

Therfore a dump valve if set right can improve throttle response, but one that just dumps whenever you lift off will reduce it.

 

I know what a dump valve does Mark , infact Gary's definition is better!
I was just debating to the people who just dumbly state they do NOTHING for performance

Truth is they do help, as what's said above. And less stress on the compressor wheel, and thus why they are fitted as standard.

[Edited by ALi-B - 11/12/2003 12:05:31 AM]

 

My forge re-circ coupled with a K&N induction kit from G.Goode has made little performance gains, but who cares, it sounds nice.

 

oh, and a 2nd performance influance of an ATM dump valve....

It ***** up the fueling (if only momentarily)

 

I have also heard the standard dv is good enough -look in Jap Performance Mag for the article on the S202 - it has awsome performance and a standard subaru dv

I changed mine to a new turbosmart adjustable re-circ dump valve on the premise that it would decrease turbo lag - however I think it just does a better job of looking shiny - all show and no go?

Atmospheric dump valves sound awsome on the track, but would get on my nerves on the way to work every morning.....

 

I like whoosh, pop, fart and bang

 

Bonfire night was last week Brun!

 

Bonfire night every night round these parts

 

You have a point there!

 

Tried your local gay bar?

 

 

LMAO..

 

dark blue mark......Apart from the delay which i thought was just 'lag' how can i tell if the Dump valve is broke or not? you've got me worried now!!

 

I have a HKS SSQV on mine and the car feels better to me. Mind you I wouldn't care if it didnt as it sounds mental when pushed.

Around town it doesnt make a sound.

Very happy.

 

Sound Good!!!??

Dump Valves sound awful, if you want that sort of noise then drive a traction engine!

 

It was rhetorical question Mark perhaps I should have re-phrased it and added some sarcasm. It was aimed at the people who said that a DV did nothing for performance

 

Ah, I see.

MB

 

I have just changed my OEM DV to a GFB Hybrid it is 50% recirc and 50% VTA it is also adjustable either way.

When I fitted it I noticed less turbo lag and quicker throttle response. As to what performance gains I got? well I have no idea it still isn't an STi6 but it is a lot smoother, the VTA whoosh bit is a bit anoying but I can live with it.