wastegate chatter

[stuart wizy]

my exahust is straight through no cats with 5" racing beat back box ie very free flowing. I got the car from japan cheap with a blown engine and tim rx motors built it for me and i put it back in, it has a std mount trust ic blitz induction apexi fc and a blitz boost controler.
The motor runs sweet with 280 rwhp dynoed at wgt but the way the bltz boost ctrl set up cuts the standard boost circuit out on the front actuator.
when my car goes into vacuum of boost i get a waste gate flapping noise for about 2 seconds, then as soon as any boost is applied is stops instantly,the boost cntrler is controling boost very well by the way, really well acording to pip.
on the front actuator one port is blocked for the controler,is this port used as a vacuum pipe on standard boost circuit to pull the waste gate shut?
why is my waste gate flapping its ****ing me of!
could it be because my engine is very free flowing?

[cjr]

could it not be blow dump valve:) never heard wastegate chatter myself

[strange_days_uk]

Do you have an atmospheric bov, as this would be the noise ?  If you have the standard re circ valve, then clearly it isn\'t opening properly at throttle close, and you ought to check all the hoses to and from the vavle.

The small diameter hose coming off the top of the standard valve is the pressure/vacuum hose that will help to pull the valve open at throttle close, so if you have blocked that then it won\'t open properly to release pressure, hence the chatter.

Simon..

[zevans]

Might not be your wastegate - in fact it probably isn\'t. More likely back-pressure when throttle closes getting back to the turbo, where the compressor blades create the flappy turbulence that goes "wuppawuppawuppa".

Does it sound like this? (200SX with recircs blocked.)

http://download.jull.net/pigeon.mp3

My 200 has lazy recircs - they work at 7psi, and I get a quiet "choo" on upshift, but full-bore upshifts from 3rd-4th at 9psi make a proper racket because the recircs aren\'t quick enough. All the same theory on an RX7 tho...

If you don\'t have dump valve or recirc, you\'ll get this, and equally if your dumpy/recirc is stuck shut you\'ll get this, as suggested above by someone else...

[RAW]

Might not be your wastegate - in fact it probably isn\'t. More likely back-pressure when throttle closes getting back to the turbo, where the compressor blades create the flappy turbulence that goes "wuppawuppawuppa".

Does it sound like this? (200SX with recircs blocked.)

http://download.jull.net/pigeon.mp3

My 200 has lazy recircs - they work at 7psi, and I get a quiet "choo" on upshift, but full-bore upshifts from 3rd-4th at 9psi make a proper racket because the recircs aren\'t quick enough. All the same theory on an RX7 tho...

If you don\'t have dump valve or recirc, you\'ll get this, and equally if your dumpy/recirc is stuck shut you\'ll get this, as suggested above by someone else...

hmm this is interesting. i get exactly the same noises you have described on my Fd at the same boost levels. i heard the same noise on a video of someone off here doing a few laps of a track so assumed it must be the BOV (i have a Greddy) and that is is normal. it appears that isn\'t the case!  it makes sense because i have tried adjusting the hard/soft setting on the BOV and it doesnt really make any difference to the noise.

Finally, whats the cure if it is stuck!?  :3Confused

[MikeLMR]

compressor surge is the cause of the noise commonly refered to as wastegate chatter I think.  Its a pretty scary noise when the compressor doing the surging is good for 16000hp :eek More of a loud boom

[zevans]

it makes sense because i have tried adjusting the hard/soft setting on the BOV and it doesnt really make any difference to the noise.

That in itself suggests it\'s not doing anything useful currently

Finally, whats the cure if it is stuck!?  :3Confused

Er... stick it on eBay and buy a Bailey recirc? Don\'t really need a recirc until you\'re running well over a bar anyway, IMHO, and an atmos dump valve you just plain don\'t need.

[Kieron]

STOP

Love it when peopel call compressor surge wastegate chatter  
On a car forum I use to visit the banter section was called that (wastegate chatter)

CARRY ON

[zevans]

I said that several posts ago, so...

...no need! no need!

[Kieron]

bring back Mark and Lard  :p

[Ricco_04]

Whooooooooooooooooooooooooooooooooooooooooooooo!  :Giggle

[stuart wizy]

when i say chatter i mean a mechanical ticking sound not a whoosh, a bit like dropping 10 ball bearings on a thin piece of sheet steel or a quick rattle.
It is deffinatly a valve rattling intermitantly on its seat, which valve i dont know!
its anoying though cause it doesnt sound good at all
i know what the guy means about  200sx cause i used to have a s13 my self running a bar on std turbo with stronger actuator spring in, this would flutter a bit like a dump valve when of throttle after full boost, very nice sound actually!
I also tuned a couple of 5 turbos with garret t3 turbo with 20psi they are a loud flutter!
all i can think of is its the way the actuators works on the rx7
it uses pressure to push out and vacuum to pull back, a very comlicated boost syestem
when you cut the standard boost circuit you plug the port on the actuator that is used for vacuum as blitz controller drawing, thus no pull back in vacuum

[RAW]

so are you saying this fluttering noise may be normal for RXs? like i said i have heard it on a track day and the bloke had a single turbo running sweetly. i have also readjusted my bov to loud and its def different to the quiet setting where there is almost no fluttering/chattering noise at all.:xconfused