which is the best??
and what is the benefit of both ...

cheers

 

Both the same thing.

No need for either.

Be a man, run with it.

 

The most anoying thing you can put on your car, mine laste 20mins before i ripped it back off.

 

same thing, yanks and japs call it BOV

 

Chav valve...noooooo!!!!

 

Neither. Both gay as each other.

 

well just because a bunch of insure guys on PF say its gay do it anyway

 

Different things...


I'd go with a BOV at a push... DV's are strraaade urrrrp homo

 

no theyre NOT different things

prove me wrong

 

Is a BOV just a glorified diaphragm DV then? always thought of them as separate things...

 

The BOV was invented so people with dump valves would upgrade to the same thing with a different name.

 

Naaah it's cos they whooshh not tshhh innit cuzzz...!!

 

it is a device which takes excess pressure on overrun and removes it from the intake system.

HOW it does it differs on a number of designs

 

whats the benifit of fitting them? i mean does it prolong the life of your engine/turbo??

 

Does it come down to forces then...? or just purely what's applicable? why could a Scoob run a Baileys twin piston with 2.5L but RB Skylines I only ever see with BOV's? (generic I know)

Got me thinking on twin scroll turbo's now too, would they always need a DV? could you still stall them with big boost?

 

The purpose of a blow-off valve is to release built up pressure in the compressor housing into the atmosphere, significantly reducing the likelihood of backspin
the turbo stays spooled up, there is no compressor slow down due to stacking.
and the turbo lives longer due to boost not stacking up on the compressor blade.

Stacking is when the pressure in the intercooler hose's is greater than the turbo output- that's the noise you hear when you change gear with an element air filter, and it's very bad for the turbocharger.

With a high boost engine stacking is even worse!

 

In theory yes.

But I know loads of car running 2 bar+ on GT35's, GT30's, GT28's, ect without dump valves, no problems. I'm yet to see any proof that it signifiacantly reduces turbo life span. IHMO of course.

 

Ok, so all compressor stall, stacking, boost, turbo specific's aside to a degree... how do certain types of DV apply to certain engines or setups? those that do run them?

I've genuinely always seen it as someone choosing to go with a DV or a BOV, my rule of thumb is gone, devolution...

 

most cars running big gt30s etc dont last that long anyway so i dont imagine it would matter to them, im talking 100,000miles lifespan.
i think they do aid lifespan but i haven't personally got any solid proof, only that a good friend of mine has an rx7 with almost the same spec that flutters away, mine had a HKS BOV fitted in japan. at 70,000KM his twin turbos were absolutely shagged. myns only at 62,000KM but they are not even slightly worn when i rebuilt it. both cars run turbo timers aswel.

 

we run1 on the frst. Its not running massive boost but better to be safe and all that although chatter does scare people

 

chatter is better than both

yeah repost i know....but listen and tell me you want a dump valve after http://www.youtube.com/watch?v=bfVNIZ0RKik

 

well tbh that does sound rubbish lol but i've heard some good noises from them,but i certainly wouldn have that one on my car too long if i heard it sounding like that....

 

in that video you can hear wastegate chatter or turbo flutter whatever you want to call it, the car doesn't have a BOV its just a noise created on lifting off the throttle, the noise is the air compressed by the turbo passing back through the compressor wheel of the turbo after the airflow is abruptly halted by the throttle closing, called compressor surge. However, in some cases, i.e. where the throttle doesn't open fast enough or is set up to only react to high boost, some chatter will remain.
The chatter noise is very noticeable on World Rally Cars, where anti-lag is used.
A compressor stall like this can cause excess stress and wear on the turbo's shaft or bearings under higher load applications of the turbo at like around 15psi and greater depending on the trim and flow rate of the compressor side.
Actual wastegate flutter occurs instead under partial boost conditions such as partial throttle near the boost threshold. It sounds like FftFftFft not ShuShuShu and is caused by the rapid opening and closing of the wastegate at boost levels near the spring pressure.

 

Comp. surge happens when throttle is open and is the real killer of turbo's. Closed throttle comp. stall most turbo's can hack but the gt's dont appreciate the abuse so much.
If you dont like the noise use a recirc DV/BOV.

 

i dont think chatter sounds that good tbh...

 

Chatter always wins...

 

I like the sound of both to be honest. I had a hks BOV on my evo and had DV's in the past. Im in 2 minds wether to put one on my current s2 but i dont want to ruin the standard looks of the engine bay.

It seem's just because a few people on here say DV's are gay everyone seem's to jump on the band wagon like sheep

 

I love the sound of turbo chatter.Im gonna keep my dump valve on cause the samco hose looks shit with a chrome bung in the hole.

 

I have never ran one on my cossies over the years.

A few have had them fitted upon purchase but they have been promptly removed.

It all goes back to when i got my 1st cossie back in the very early 90's and spoke with Ahmed. He told me not to run one with his board so i never did.

 

so do you actually need 1? or is it a waste of £100 or so?
if theres no real benifit why fit one? other than the noise, can't decide if i want one or not but if theres no real benifit i wont bother.

 

im going to run 1 on the focus when the boost`s upd.

 

Don't. There is no benefit to fitting one whatsoever and due to how the Bosch KE-Jetronic system works it arses up the way the car drives and you will often have stalling and idle problems. Even those who love dump valves will usually admit the RS Turbo drives better without one.

IMHO do not fit one unless you really have to. My Escort doesn't need one and is running 25psi so doesn't have one. My chipped A4 does require a recirc valve due the way in which the fueling setup works, as such it has one.

 

Bit of bumpage, anyone know?

 

the type of engine dosent affect the BOV/DV,
the only things that affect it is the amount of boost you are running and the inertia of the turbo, with a big turbo like a T4 or something bigger running on a jap sled, the turbo takes longer to slow down when you close the throttle

(hence why rally cars "chatter" for longer)

dump valves just "dump" any pressure between the turbo and the throttle body outside the inlet to stop it running back through the turbo slowing it down.

if you had a turbo that spooled instantly and stopped instantly the moment you closed the throttle, you wouldn't need a BOV/DV

 

Can you run a T4 without a dump valve at about 34psi?

 

Not recomended. I beleive the rule of thumb with the Garret turbo's found in RS's is anything smaller than a T4 and/or sub 30psi of boost