Hello all, bought my first impreza 2002 bug eye wrx. Have been told to go for a Bailey DV but would like confirmation from other owners and what they have fould to be the best! Many thanks! Stu

 

What do you mean by 'the best' ?

Do you mean in terms of 'removing the pressure in the intercooler to prevent damage to the turbine blades and to stop them stalling due to reverberating air in the chamber, whilst protecting the MAF sensor that the ECU uses to read the airflow', or in terms of 'making a whoosh noise, whilst not necessarily providing the ECU with true readings' ?

If its the former - go for the recirc already fitted.

If you've replaced the inlet with a system that won't take a recirc, and the turbo is OK with it (e.g. TD05), then remove the DV and block it off.

If its the latter - err - wait until someone else comes along that has experience of 'noises'

I had a forge on my old classic (a recirc) for 3 days, then reverted to the original. After I fitted the Prodrive inlet, I ran without one for 6 months.....

Sorry to sound negative - don't take it personally - someone will be along in a minute to tell you that the atmos. ones are fine -

Mark

 

Just read your other thread, so I thought I'd try a bit of a better explaination.....

The standard car comes with a dump valve - it is a recirculatory type, that flows the 'boosted' air back into the inlet system. As this system is self-contained, there is no 'woosh' noise, though you may hear it slightly with a high-flow panel filter or induction kit. The 'dump-to-atmosphere' type effectively puts this air back out of the system, sometimes even through a 'trumpet' to make a loud noise. This is air that has been metered into the system by the ECU, via the MAF sensor. The ECU will cater for this air by adding more fuel. If it is then dumped out, the ECU will effectively be over-fuelling.

Hope this helps,

Mark

PS _ You'll find that 'dump valves' are an emotive subject on here

 

BLITZ are the loudest ive heard so has got to be the best because that is all they are for plus you get plenty off bangs and the odd flame. when decatted.

 

I have a Turbosmart Dualport on mine (2002 WRX like yours). This basically uses the original recirc design under low to medium revs, but Vents To Atmosphere (VTA) under higher revs and then produces the pppppssssssshhhhhhh noise associated with VTA dump valves - this one is reasonably loud.

I have read loads of conflicting information regarding dumps valves on here, but will offer my own experiences. The OE dump valve worked fine but did tend to make gear changes 'jerky' when driving the car hard as the turbo would slow quicker and require a split second to re-spool - hence the jerk.

After having several other mods done to my car I opted to have the Turbosmart dump valve - which is not the cheapest (approx £230) - partly for the noise (although if driven under lower revs it is quieter which suites me) and partly to improve response between gear changes. Result = the car drivers perfectly, no hesitation or stalling problems like some people report after fitting aftermarket DV's. With regards gear change performance, the car is transformed and responds immediately.

With the Turbosmart Dualport you have three different configuration possibilities, these are 1. Recirc, 2. VTA or 3. Both (dual) which I have mine set to. I can honestly say I have not experienced any negative effects in approx 10k miles.

 

This is a comment I have heard a few times on here - and I'm not about to disagree as I'm not an experienced enough techie to fully comment, although I do have a basic understanding of things.

However, I have had my car remapped (by a well respected Subaru mapper) and I asked this very question as I had read this on here. I was told that the ECU does meter air into the system, but is not clever enough to fully monitor the amount of air 'recirculated' back. This is one of the limitations of the standard ECU / EcuTEK and is one of many reasons an aftermarket ECU (for e.g. Motec) would be used. Hence a VTA cannot cause excessive overfueling.

I'm not saying I have this 100% correct but this is my understanding of what I was told?

Any comments as I am genuinely interested in this.

 

This is helpful and something to think about

I have noticed the sudden jerk in changing gear at high revs but put that down to my inexperiance in driving turbo powered cars! It sounds like this is the sort of thing im after because although many people frown upon dump valves as they sound chavish and boy racery i can kindda relate to this and wouldnt want to be rolling through town or my housing estate in 1st or 2nd gear and having a loud pssst every time i change gear, i can understand how stupid this could sound.

But with regards to the gear change and turbo spool i can see how a dump valve is beneficial higher in the rev range.

Where can i get one of these dump valves from and how easy are they to fit??

 

With regards the noise, I would point out they are not absolutely silent all the time under low revs - there are certain 'part throttle' situations where the dump valve will release a quiet ppppsssstt - but certainly no where near as loud as under full load. The car can certainly be driven down a high street without it doing this once you get used to it.

Fitting of the Dualport is quite easy. Depends on the configuration you choose. VTA is the easiest - simply bolts onto the intercooler - with a blank for the recirc pipe, whilst recirc only or dual are still easy, just a little more arkward to get the pipe connected to the base of the DV without loosening or taking the Intercooler off - still not a massive job.

It's also worth noting, if you wish to have a specific type of Turbosmart DV - recirc (referred to a 'plumb back'), VTA (referred to as 'supersonic'), these are cheaper than the Dualport but cannot be converted to different configurations. Several places do them. Have a look at these links:

http://www.aet-turbos.co.uk/blow_off_valves.htm

http://www.tsl-motorsport.co.uk/news...000§ion=300031

http://www.wrc-tech.co.uk/subaru-02sti-bov.htm

Hope this helps. I have seen quite a few different types of aftermarket DV and am aware there are many cheaper than the Turbosmart ones. However, the quality is firstclass.

 

Still interested to have some comments on the above quote. What do people reckon?

 

For what its worth (And if I understand this correctly)

- the ECU cannot monitor the recirc'd air - that's the point. In the closed system (recirc), the air 'recirculated' has already been measured, on its way into the system the first time. When its 'dumped', its actually fed back into the loop, between the MAF and the turbo, so the Engine still receives the amount of air metered. If the air is vented to atmosphere, then the ECU has to 'assume' that the air is still in the system (it doesn't know its gone elsewhere), so fuels accordingly (i.e. too rich) - this is why VTAs sometimes cause pops and bangs - this is the 'spare' fuel....

If an aftermarket ECU is used, this can be avoided - specifically, the new ECU should be one that uses a MAP sensor, rather than MAF, where the MAP sensor will 'know' that the air has gone and the ECU can re-fuel to adjust.

In principal, the VTA and Recirc should both avoid turbo stall equally well, but the recirc will avoid the fuel problems and be quieter.

I can honestly say that my 98UK recirc was fine at avoiding turbo stall - but then I didn't have any problems once I was running with no DV at all - though I had a large FMIC. Its also worth noting that I could see the effect of the air flowing backwards through the MAF, via the hand-held commander screen when no DV was employed - which I'm sure must have confused the hell out of it !

Its also worth saying that I could hear turbo stall with no DV, particularly when changing gear under partial throttle (with slow 'usual' changes), but that I could not notice an effect when accelerating hard and changing gear quickly.

My 02 STI UK has the original recirc - which seems to perform OK too.

I'm happy to discuss and be challenged on this, as I'm no expert ! (just have a little experience)

Cheers,

Mark

 

Remove the air resonator from the drivers wing and run in some pipe. You get a slight noise from the dump valve (not quite as loud as your local bus doors opening(stops the old ladies getting up off the seat in the bus stop.......... )) but at least you're sticking with the standard system

 

Only GFB for me......... Completely adjustable between recirc. and VTA.

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