tubbytommy

iTrader: (20)

on a serious note then has anyone actually had an engine fail due to fitting a dump valve??

mickywrx

iTrader: (29)

Most of the dump valve questions on here used to come from people that had just acquired an early car, and I'd guess their ages would have been in the early 20's.

They read crap in crap magazines and then it all snowballs....

My input on this thread onwards is only from my own experience, unlike my opinion above.

Bought my car in 2005, one of the 1st things I did was fit a VTA. At the time I liked the sound of it, and yes I'm anti-social. It caused no running issues with my car. It must have done it good though, as apparently 380cc injectors can't support 330BHP.

Ran my car with it for a good while, used and abused, and got sick of the noise.

Binned it off, and ran my car with out a DV for about 6 months before the noise got on my nerves, but, once again caused no running issues with my car.

Went back to the OEM recirc a good while back, and it still drives the same. The noise is starting to get on my nerves though, not a lot I can do about it though running an FMIC. I could get the compressor housing converted to FE, and use a later inlet pipe setup. That might quell some of the noise.

Edit to add, my engine has never been apart in my ownership, and it's never been remapped.

jura11

iTrader: (7)

Hi there

Maybe my answer and response will be subjective,but here is my experience with running with/without

We run previously on our wagon like DV(Forge VTA DV on VF34 or TD04) or DVless(on TD04,MDX321T)

If I'm comparing running DVless with DV on TD04,I would say we are never feel any difference in better spool up(as some DV makers claiming with DV you will have better spool up),car has run same like on DV or DVless(no problems with the idle or MAF problems)

On VF34 we went with DV(Dump Valve) for few weeks just due VF range of turbo are not the strongest(agree this can be the case of the older range,not the newer,but still same aged TD range is stronger than VF),same view on this,we never seen any difference in running or running without DV

When we run MDX321T we decided to run DVless,before we spoke with the Mark@Lateral performance and he said,we can run DVless without the problems and we will be covered by warranty,Neil(our engine builder and our tuner) said us we will be OK to run DVless and he never have any problems with running Garrett based core DVless

Now we running 35R and too we are not running any kind of the DV,not sure if I would ever run any kind of the DV on my car,but that's the down to the personal preference I would say at least

Some guys have problems before with running DV on their cars,but this can be with wrong DV itself(Bailey Dump Valve is most known on Subaru be problematic,but again this can be subjective),wrong spring(some springs can be weak)

There is no definitive answer on the pro and cons to running with DV or DVless,there is no definitive answer on the DV/DVless can cause failure of the engine

With running DV we never have running issue with this,at first time we loved the noise of the DV,but after few months we been fed up with the noise of the DV and we are ended with running the DVless

I would stay at least clear of the Bailey DV and some eBay ranges,with the Forge VTA DV we never have any problems as previously I've mentioned


Hope this helps


Jura

thenewgalaxy

Edit - thanks mods for clearing up the above, thread turned into a bit of a flaming war.

I have contacted some of the most highly respected people on these forums who either have amazing cars in high states of tune - and those who build those engines themselves - and unfortunately the controversial nature of the dump valves themselves combined with the way this thread is going has put them off posting their opinions.

Dan has asked if there is any evidence to support uprated dump valves causing damage to engines, because there is a common opinion that VTA can damage the MAF and can cause overfilling and potential bore-wash.

thenewgalaxy

Most informative post from a man with experience so far, thanks for your time Jura.

So anecdotally no increase in performance but a problem with a well-known and popular range of aftermarket ones if the wrong one is chosen.

I guess if you're going for a mega-engine then it is strong enough to deal with the high pressures involved and is therefore preferable to remove them from the system as there is no benefit to running with or without one...

Mustoe91

iTrader: (2)

I done my research on DV picked up a turbosmart one been on for 2 months and don't like It just haven't got round to taking it off yet

banny sti

iTrader: (68)

On my first car whilst it was still on the power fc with a fmic, I got all excited and fitted a baileys chav valve. **** me worst thing I ever did, car would kangroo when ragging it, defo over fuelled and dv was always slightly leaking air so didnt spool as quick.

Switched back to the oem plastic re-circ difference was night and day, so much smoother and overall nice to drive. Moved on the syvecs and went dv less and stuck with that ever since as it sounds great and boost recovery if you flat shift is mint

Bro on his JDM twin scroll has a Tial vta on running mafless drives nice but just cannot do with the sound and boost recovery is not as good as dv less in my experience.

bluenose172

iTrader: (2)

I can only vouch for the HKS SSQV that I fitted to my 2001 wrx test mule. I've only noticed a negligible difference when lifting the throttle in afrs , it might dip into the high 9's on occasion. (Data logged) That's from low 10's with the standard unit. I also noticed no issues with idle or cruise or any massive swings in my short term fuel trims. Apart from the pssssst sound it works perfectly!

LuckyWelshchap

Plus of course everyone scrapping like rats in a sack.

APIDavid

iTrader: (4)

Not sure looking at some of the posts on here whether i want to walk into a minefield. But l'll tread very carefully.

I do not advocate replacing a dump valve on standard cars, as the OE part is adequate for the task it is asked to do. However they are mass produced and made as cheaply as possible. They do wear out which is about the only reason I can offer for changing one for better -- recirc of course..

For that reason we use, fit and recommend Forge brand recirc. It is a properly engineered part with variable spring rate options. Red spring is generally the correct one for mildly tuned Subarus. There are other spring options, but in my experience, high power cars run remote wastegate type turbos and a dump valve then becomes a different matter altogether. Some customers ask for VTA and after I have given them a lecture about why they shouldn't, they make their own mind up. [ see above posts relating to MAF and measured air and so on ]

We do run certain applications from here without a dump valve, as customers like the different noise it makes as it 'stalls' the turbine wheel, But that could be dangerous on an older turbo. Whilst l have never seen a turbo break any blades for the reason of not having a DV, I'd hate to have to explain why I am not responsible for his 12 year old turbo falling to bits cos I didn't fit a DV.

There is no performance gain by fitting a properly engineered dump valve except that if the OE part is not operating correctly and is venting all over the range. But of course it would then be arguable that fitting another standard part ought to restore the performance loss from a worn out part,

So by fitting an aluminium, properly manufactured, correctly sprung, recirc dump valve all you have done is take away the uncertainty of using a mass produced item. No harm in that.

A Bailey DV is a no-no on a Subaru, the spring settings are far too weak. As soon as we see one it is a case of " Well there's your problem ".

David APi

trails

iTrader: (41)

Thanks David, useful post...especially as we agree

yabbadoo4

iTrader: (8)

thanks to david for responding to this post, good to have a professionals opinion. what david said regarding baileys dv,s certainly rings true for me. my wagon had one fitted when i bought mine and the spring was sticking open and dumping boost. it probably did me a favour as i got the car for a good price with that as a bargaining tool so i bought the car and removed it and fitted a forge instead and its been fine. ive since had the wagon mapped and running a nice 315 bhp from andy f with no problems for a year and a half. and on that note if fitting one is such a bad thing why dont the well known subaru mappers refuse to map cars with them fitted if they are so damaging to engines? or at least warn that they wont be held responsible for any engine damage caused by running them?

thenewgalaxy

David I am ever so grateful for your input - especially on such a controversial topic - and it is great to hear from Banny and Jura who run cars in high states of tune. And thankyou Shaun for your input also, you kicked off the sensible discussion with your points that have been echoed again.

I think we can say with a high degree of confidence that:

An uprated dump valve will not increase performance if suitable for your engine but may cause performance issues if not appropriate for the application

The standard recirculating valve is not appropriate for very high end applications as it cannot cope with pressures over 25psi

No one so far has recommended the use of VTA

Those with experience of building and running high performance engines discourage the use of VTA as part of a setup involving MAF. It can, for one example, lead to over fuelling and theoretically toward associated issues of running rich (e.g. bore wash etc)

VTA can be used as part of a mafless remapped setup if you wish but it's only to make noise

The standard OEM part is built to a budget and failures of this part have been recognised but this can be sorted by replacing like for like

We can fit with much confidence a highly engineered aftermarket part as long as it is recirculating type and some specialists advocate their usage on the basis that it is constructed to a high standard and has the correct spring strength.

As with all aftermarket parts some dump valves are built to a high standard and some are not!

It would appear that some aftermarket dump valves do not have internal parts appropriate for use on Impreza engines.

Some dump valves have adjustable spring settings and therefore it would be prudent before fitting one to consult a specialist with regard to the appropriate strength and reasoning for fitment.

Setups without dump valves are sometimes preferred by owners

[Question - is there an advantage to this?]

Running a setup without a dump valve certainky makes a nice noise but may cause issues with older turbos that are not up to the job

LuckyWelshchap

Well fwiw I feel more certain now that this thread would make a very good sticky.

We've seen how much division the question of DV - to have or not to have? - poses. There's such a difference of opinion that anyone asking the question is likely to be more confused because of such wide-ranging advice.

However, API's post has summed up applying common sense in the light of the technical advice and discussions here.

Anyone reading that has the opportunity of getting advice from someone in the business, which is supported by highly technical advice from other experts/businesses and the experience of enthusiasts (and which is available in the same thread), and surely thay can make their minds up from that?

I personally feel that I now know much more about DVs, the theory behind them and their effects. I might not need that knowledge, but it is nice to have.

I've found it very interesting tbh.

Finally, as the OP said or implied - there are many differing views, reasoning etc. and 'this' thread is intended to bring them all together in one place.
It's certainly given food for thought - hasn't it?

mrmadcap

[quote=mickywrx;11158912]I don't recall resorting to personal insults, it's you insulting me, you need to calm down mate

Maz

iTrader: (34)

Are you incapable of partaking in a discussion without showing yourself up to be a complete and utter prat?

Ps I don't think Micky is your mate.

mrmadcap

Listen pal, people come on here and ask advice on dump valves, blow off valves call them what you will.

Now I wouldn't have one of these on my car but that is just personal choice.

However we get the same types jumping on the bandwagon and slagging off the people with the chav label etc, and of course, it's just banter isn't it?

Except when I point out that the people ganging up on others and having the 'harmless' banter are the people sticking fake carbon on their cars.

So do you see the irony, dump valves - stick on fake carbon? That is checkmate in my book, so give them some friendly advice and move on.

At the end of the day it's all down to personal choice

tubbytommy

iTrader: (20)

nobody was slagging anybody off on here, but I do love your obsession with fake carbon.

for the record I think its **** too though.

mickywrx

iTrader: (29)

I don't think Maz is your pal.

FWIW, that's possibly the most sensible post you've made to date. You didn't fail with the quote, which is a bonus.

Opinions are like arseholes, everyones got one. It's how you put it across that makes all the difference.

Anyway, back on topic.....

mrmadcap

Bonus? I know that place, it's in the Lake District next to Windermere

Maz

iTrader: (34)

Micky
I take folk as I see them and I agree the last post mrmadcap made was refreshingly philosophical. As you've alluded to back on topic...........

tubbytommy

iTrader: (20)

so has anyone had an engine fail due to fitting a dumpvalve or even had one damaged??

thenewgalaxy

On theory alone a VTA would eventually screw an engine, surely there must be some failures knocking around out there.

David at API mentioned that people had experienced problems running Bailey dump valves as the springs aren't suitable but didn't mention any engine failures. I'm assuming if a recirc valve doesn't have a strong enough spring it effectively runs as VTA?

I cannot say I am aware of any failures and I'm thinking of fitting a valve set to fully recirc as a bit of engine bling.

I have a further question to ask - is there any benefit to running without a dump valve as the suggestion so far appears to be otherwise. It would make me wonder why competition cars run without (when in the past they used to)? Is it because they have to run very high pressure continually without worrying about the engine needing to last more than a few hundred kilometres?

tubbytommy

iTrader: (20)

in theory yes but has anyone got one that failed.

im aware of the issues they can cause but as we are having a sensible thread on dump valves for a change can anyone offer proof one damaged there engine??

LuckyWelshchap

Dear Lord, please let me be sober enough to understand this in the morning after the night of Pool.

APIDavid

iTrader: (4)

I'm not of the opinion that a VTA valve will cause a failure in the immediate sense. But what they do of course, is thoroughly confuse the MAF & the Lambda, which cannot do anything good to fuel consumption. As mentioned above, the DV is not connected to them electrically, so the necessary controls for fuelling are missing.

Imagine a 'conversation' between the various parties.

MAF "Righto Lamdba, there's all your air "

DV PSSSSSSST

Lambda: "Where?, sh*t we're way too rich, cut fuel!!"

DV " click "

MAF " Oh sorry, here's some more."

Lambda " Sh*t, where did all that extra air come from, add fuel quickly!"

Repeat that every time you hear a VTA. It cannot be good for fuel consumption or fuelling and fuelling related temperatures in cylinder.

Long term it'll harm the engine. It must. Just depends who is holding the parcel when the music stops.

David APi

Mr Footlong

iTrader: (7)

Love that David .

Maz

iTrader: (34)

When I had my first Impreza a MY97 UK Turbo, I made the mistake of swapping out the oe dump valve for a Blitz vta. The first time I gave the car a little gas and dipped the clutch to change gear I was greeted by an almighty bang, akin to a gun being fired. I pulled over to check what had happened (and change my soiled underwear), nothing was apparent so I carried on.
Over the course of the next couple of weeks the car gradually started to run worse. Hesitating, feeling sluggish and constant popping and banging from the exhaust (that's where the first bang had come from). My fuel economy was nigh on in single figures! I had a chat with Andy@Richard Henry who advised me to swap back forthwith. Had the dump valve been left in for much longer I'd have wrecked the engine through bore wash. The fueling was so rich it was off the scale! Lesson learned dump valve removed.

Ash170990

iTrader: (1)

after reading that im buying the loudest dumpvalve i can find

thenewgalaxy

With a VTA you'll have even more trouble keeping up with Fiestas

You can get a loud recirculating valve, GFB do one that can be set to fully recirc. I had one on my Blob, removed the trumpet as it sounded ridiculous.

http://www.gfb.com.au/products?page=...ategory_id=210

What I don't understand in the lingo beneath though is that they claim "GFB TMS improvement is seen as a 30% faster return to peak boost, during which time up to 40% more boost is available" (On a CA18DET with a T28 turbo, whatever that is)

Sounds like a load of baloney to me, unless I'm missing something.