I've got an HKS SSQV and sometimes I can hear it flutter rather than a continous dump sound. I'm always confused as to what is really making this noise either the DV opening and closing rapidly or the dv not opening at all and its the sound of the back pressure over the turbo vanes - or indeed something completely different.

Thing is I've heard a couple of scoobs with the flutter noise rather than continous noise and I would prefer the flutter noise but don't know if changing the DV will achieve this.

Cheers in advance.

 

if you are referring to the chattering noise that WRC cars make quite loudly then I believe its the blades on the turbo stalling

 

No not that. Some road cars that are fitted with certain makes of DV make a flutter noise rather than a continous dump noise. A friend with a GTIR had the previous version of the HKS DV and that made a flutter noise.

 

The SSQV has two ways of dumping. The quieter flutter will be with low boost

 

As far as I know it is the dump valve. It used to be really obvious on my Esprit where there was a VTA valve - a sort of wooshing sound when coming off boost. If you have a DV fitted then there shouldn't be much more back pressure over the turbo vanes than there is under normal boost conditions - that's why its there.

IMHO fluttering rather than the continuous sound is more likely to be down to someones driving style than the valve. If you think about it, all the DV consists of is a plunger held shut by spring and air pressure from the manifold. When you take your foot off the throttle the manifold pressure becomes a vacuum so the pressure in the intercooler pushes the plunger down and opens the valve. If you only partially lift then the DV will only partially open and will oscillate slightly giving the fluttering noise.

Matthew

 

The noise will probabaly be either or both the dv and wastegate chattering as the dv keeps rapidly opening and closing the wastegate keeps seeing varying pressures and rapidly opens and closes as well - making the chattering noise

In other cases the dump valve spring is too strong or is incorrectly adjusted and the DV is not opening which causes the wastegate to chatter as it slams open a shut.

Not a good thing - a decent well adjusted dump valve (like the OE ) will have some hysteresis (or dampening) so once it opens it stays open or closes more gradually rather than slamming shut again (forcing the wastegate to open).

 

.....clipping a playing card to your spokes with peg........

 

I know what you mean mate and its the dump valve as its a common noice on GTiRs they normally use the HKS stuff and if its the one your mate has then personally i dont like the noise as i think it sounds like an underwater fart! IMHO Willsy

 

used to hear this type of sound often on my old 97 uk turbo fitted with bailey dump valve. its the wastegate mate.

 

should also add my mates GTI-R flutters more than my one, different type of engines make different noises

 

are you sure its not the boost solenoid you can hear. Mine is really loud and sounds a bit like what you describe.

 

My legacy has a bailey dump valve and never fluttered at all but after fitting a TD05 the other week it now does on every gear change.

I was fairly convinced that it was maybe a problem with the valve not quite working as it should be and some backpressure hitting the compressor vanes.
It's hard to describe but it sounds more like a kind of whistly flutter rather than the sort of cheetering noise you hear from the wastegate flutter on rally cars.

 

Had the same thing on my old cosworth, years ago. Its the wastegate - the rod that comes out of the back of your actuator, this joins a "flap" on the turbo. The noise you hear is this flap/rod opening and closing. Its often refered to as sounding like a pidgeon.

 

Nope, HKS ssqv's CAN flutter at certain times. On part throttle in 5th about 100mph mine used to flutter when backing off a bit. Before I sold it that is (waste of money).

Wastegate flutter is incorrectly named, and a different thing than the thread topic. I know for a fact that if you disconnect the boost control pipe, hence keeping the wastegate permanently shut you still get the flutter. It's the turbo stalling, air from the inlet flowing backward from the inlet pipes out through the air filter.

Dave

Oh yes, and they're two noticably different sounds

 

my old 200sx used to do it but it was the wastegate chattering.