Wurzel

iTrader: (1)

Watching the street car shoot out yesterday some of the cars with VTA DVs made a slight whistling noise when dumping, I have a VTA DV and it makes a really harsh one off noise when it dumps so which dump valves make the more pleasent whistle rather than one big pishhhhhhhh. Also dare I say it the cars on The Fast and Furious made the same noises.

Also not being a car expert but I would assume a VTA DV should not be dumping whilst your driving, I can get mine to leak whilst still hooooooning it down the autobahn I don't seem to lose any performance but it seems abit odd that it can leak at high speed.

1 last question what is a Super Sequential BOV then???? I know what BOV means but what about the SS bit ie HKS SSQV?

cheers

Steve

greasemonkey

Presumably the ones with whistles or similar sound-modifying appendages on them.

Impossible to tell what was used for those. Knowing what films are like it could just as easily be the sound engineer's toilet, combined with the sound of whales singing, and all put through a sampler or something like that!

Correct. Leaking under boost is undesirable, to say the least. The valve should only open when you lift off.

Silly question, but if it only happens at high speed, are you sure it's the dumpvalve and not wind noise? If you're sure it is the DV, you need to either fit a stiffer spring, or increase the preload on it, whether by shimming, turning the cap, or whatever other method provided by your valve.

Lol, a way to bullsh*t you into spending an unnecessarily large amount of money for a product you don't remotely need!

Theory behind this product is that it's actually two valves - a small one and a big one. Idea is that the little one is supposed to have lower mass/inertia and will thus open first, supposedly giving a quicker response, while the larger one enables the boost to exit quicker. Does it work in practice? I'd love to see some independent research, but pending that, my opinion is that it's more to do with marketing than engineering...

Wurzel

iTrader: (1)

Hi Greasemonkey thanks for the reply.

Yes I am sure it is the DV not wind noise

eg. driving fast or slow no real matter if I lift of a bit he car still travels at the same speed but I can get the DV to vent and keep venting till I put my foot down again, it is hard to explain but I can do it more or less whenever I want.

I have GFB Hybrid 50/50 VTA/recirc BOV there is a screw on th etop with the vacuum hose on it I can adjust it in and out but the destructions say turn it so it releases the piston then turn it in 1 turn to take up the preassure. should I turn it in More or what????

Cheers

Steve

Dark Blue Mark

SS is Super Sequential.... Or Super Sad some might say

You dont need it.

MB

andypugh2000

The std one is always the best unless you are addicted to the whoosh does sound good on other cars but would seriously get on my **** if fitted to mine

Si of Sheff

[QUOTE=Wurzel]Hi Greasemonkey thanks for the reply.

Yes I am sure it is the DV not wind noise

eg. driving fast or slow no real matter if I lift of a bit he car still travels at the same speed but I can get the DV to vent and keep venting till I put my foot down again, it is hard to explain but I can do it more or less whenever I want.



Your dump valve is releasing due to the lack of boost pressure needed to cruise at a stready speed, but turbo is spinning due to the high revs of your engine but the pressure isn't needed. You're keeping your valve half open by balancing the vacuum pressure. I guess lifting off a tiny bit or a sniff more throttle and it either dumps properly or shuts up?
Does it on mine too, just take the noise as the car booing at you for easing off, and give it a bit more!

Si

Dark Blue Mark

Ok, I didnt get any of that

Its hissing because the spring isnt tesioned sufficiently to stop it lifting at low boost. I suggest you nip it up a bit to tighten up on the spring.

If it didn't have an adjuster, you could open up the valve and use some spacers to pack it out, like with the Forge one.

MB

Jay_bee

iTrader: (1)

Mine does the sames thing, usually around doing 80mph whilst trying to save some fuel. I dont think theres lot you can do about it TBH...

J

Dark Blue Mark

There is, read above.

MB

Wurzel

iTrader: (1)

Si of Sheff

Reckon you got it in one ta I wil give the screw another nip to try and tension up the spring.

Cheers
Steve

Jay_bee

iTrader: (1)

Yep, fair enough... I just live with tho, it doesnt make any difference to performance, just a bit annoying at times.

Si of Sheff

I don't think you need to. I'll try to clarify:
When cruising at, say, 80 ("no it was 68 officer"), your car does not need its turbo to maintain that speed. If its a Uk turbo, it'll be doing just over 3k rpm, which is turbo territory. Holding this speed means your car is producing a little boost it doesn't need, is it lets it gently leak out. Its not a big dump as its not been closed as it would under acceleration so none has built up.

Your dump valve is working as it should. I had the same concerns on my first motorway run after fitting it, but if the above makes sense then you'll see there's no problem

Happy hissing!

Si

Jay_bee

iTrader: (1)

Is Wurzel not from Germany... (doubtful it'll be a UK then )

But you are spot on tho, mines a UK and cruising at 80, she does hiss a touch.

dowser

Could also be wastegate opening to bypass unwanted gases and keep boost low. Best way to confirm is to blank off the DV.

Richard

Dark Blue Mark

The dump valve should not be venting air until the throttle is backed off, or its not correctly set, in my book. When boosting, the vlave should be shut tight, as you want all the compressed air into the comusion chamber. When you release the throttle, the air would be dead headed, so a dump valve is fitted to allow the turbo to keep spinning.

Again, if its hissing on cruise, I dont think its set right.

MB

Jay_bee

iTrader: (1)

What happens is you accelerate upto the desired speed then back off to maintain it. As you do so the dumpvalve starts to dump, but because you havent backed totally off the throttle IE you are feathering the throttle just enough to keep the throttle open so to maintain the cruising speed, the dumpvalve doesnt get to close 100% because you havent closed the throttle completely, hence a slight hiss on occassion.

As for not being set right, you cant really get it wrong IMO. On mine, a Bailey 'EVO' DV26 vta, there isnt any thing to adjust (i dont think).

All just IMO of course

Dark Blue Mark

They can be adjusted with spacers, and there have been many on here who had been supplied the wrong colour / type of spring from Forge, and it was causing leakage. The internal springs can e changed for stiffer ones, and you can also get spacers to put inside the housing, for fine adjustment. Not sure if this is the case with the Bailey though.

You can see from all this, how pointless VTA ones are... More bother than they're worth

MB

Jay_bee

iTrader: (1)

Phisssssssssss to that!

Wurzel

iTrader: (1)

Thanks again guys for all the info.

Dowser when are you comin upto Stuttagrt then? I reckon you might have something with may wastegate there as I am not happy with another strange noise coming from that area of the engine bay. When I back of the gas to change gear there is like a scraping noise that is very sudden then gone. NOt sure whether to worry about it or not.

could the turbo be on its way out or am I just delusional

Dark Blue Mark

It may just be a heatshield come loose on the turbo. You can get it to boost when stationary, with the bonnet up. Just rev it using the throttle arm, to high rpm, and let go. You can then hear it on run down...

MB