i was wondering something last night; what kind of noise do you get if you run a standard re-circ dumpvalve as a VTA-- i.e. blanck off the return pipe and therefore don't connect it to the re-circ? proabably nothing....which would be quite good as far as i'm concerned and i might get some pops and bangs back on the over run!









taker yer pick!
Ash

 

you may get a loud bang and a big bill when the engine goes..... other than that youll get **** all.. the recirc valve obviously doesnt release the air therefore no piiiissssshhhh

 

Not quite sure what powerwrx is trying to get at there?

Yes you would get a swoosh noise it won't be as loud as a normal vta dv as the hole is much bigger, you may well get some pops and bangs too!

Dave

 

how can the standard re circ valve dump the air ?

 

He said by removing the standard pipe and blanking it off on the intake elbow?

Basically making it a VTA

 

...because it's not plumbed into the recirc port on the turbo intake - so acts as a VTA (reread the OP's thread starter...)

 

hiya mate, cheers for reply
all it does is open and send the compressed air down a pipe instead of to the atmosphere. so no diffeent to a normal DV appart from not designed to make a noise and is connected to a pipe.... or is it? does it rely on preasure (or rather vacume) in the recirculating hose in order to stay closed properly under boost? I guess thats my real question.
i run with no DV at all so unless the re-circ won't close properly with no recirc hose connected it will surely just act as a VTA so shouldn't hassel the engine

 

Removing the re-circ pipe won't affect how the dv works at all, its basically a small exhaust pipe for the dv allowing the compressed air to go back into the intake track

Dave

 

my bad.... read it wrong

 

thanks for the replies guys, yes Claarkio this is what i am thinking... don't want a loud DV (HKS one came off nearly a year ago!!) but do want a couple of pops back on the over run :-D

 

yep what i assumed... but always good to get a few oppinons on boared

bloody hell, sorry guys i'm watching TV and posting dead slow, hence the redundant posts

Ash

 

When on boost the inlet manifold is filled with positive pressure so the DV's valve has positive pressure, bearing down, on top (via that little vac hose) and an equal pressure, bearing up, on its underside (because it's plumbed in after the tubo outlet). So the DV is in status quo.

But, when the throttle is snapped shut, the positive boost is still in the inlet tract and still acting on the underside of the valve... BUT... now there's a vacuum in the IM, so the combo of positive boost on the underside, and a vacuum above it, causes the valve to lift up and open and allowing the 'trapped' charge of air between it and the TB to escape out of the recirc port.

So if the recirc port is connected to the intake, it gets recirc'd back into the intake to aid respool of the turbo impeller again. Or, if like the OP says, it's disconnected, then the charged air simply escapes to atmos, just like a normal VTA one would....

 

thanks Joz!

 

just to tie this up...
tried it..... and it sucked

hunted horribly on idle (to the point of stalling a good few times), the revs died on their **** with every gear change so was jerky and horrible to drive, and as full boost approached it would open and dump all your boost! good for making sure you stay below 80mph though!
was a relatively loud dump (well more then i expected), but didn't sound good.

oh i did get a couple more pops and bangs but only when stopping at traffic lights when you pressed the clutch in to stop.



Ash

 

LOL worth an experiment though

 

The hunting will probably due to there being no real pressure from the turbo and with the idle valve controlling the air flow a small vaccuum in the manifold. Also as the Maf sensor measures the airflow in and the ECU calculates the fuel required when the system is working in re-circ then the air is still in the system. But by VTA the air is lost so the car will overfuel but as you want the pops and bangs your sorted.