What makes the flutter sound - turbo or dump valve?
#1
Scooby Regular
Thread Starter
What makes the flutter sound - turbo or dump valve?
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.
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.
#3
Scooby Regular
Thread Starter
Originally Posted by Andy McCord
if you are referring to the chattering noise that WRC cars make quite loudly then I believe its the blades on the turbo stalling
#5
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
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
#6
Scooby Regular
Join Date: May 2004
Location: Ascended to the next level
Posts: 7,498
Likes: 0
Received 0 Likes
on
0 Posts
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).
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).
Last edited by Shark Man; 19 April 2005 at 05:29 PM.
Trending Topics
#8
Scooby Regular
Join Date: Mar 2005
Location: Nottingham
Posts: 344
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by EddScott
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.
#12
Scooby Regular
Join Date: Jun 2004
Location: Isle of Man
Posts: 280
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
#13
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.
#14
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
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
Thread
Thread Starter
Forum
Replies
Last Post
Scott@ScoobySpares
Full Cars Breaking For Spares
61
11 January 2021 03:08 PM
Scott@ScoobySpares
Full Cars Breaking For Spares
7
14 December 2015 08:16 AM