WALKER

What must i do to get my turbo to chirp like Mr.Burns(not dumpvalve noise). I think it is something to do with the wastegate fluttering.My car is a late 99 model. Also my brother inlaw has got his cossie to do it by fitting an induction kit, which i have also done along with a PPP and a Blitz backbox. This is probably sad, but i just gotta get that noise!
Paul

MorayMackenzie

The noise is the turbo anti-lag system.

Well, you could ring Prodrive in Banbury and simply ask them if they could supply you an anti-lag system for your MY99 car. If it was an import, they wouldn't be interested, but as you have an expensive, lesser speced car I'm sure they will be very helpful!

Moray


( it is anti-lag, but you wouldn't want it on a road car.)

mike_nunan

All was explained at the end of last year. Have a look at this thread:

Ian Cook

Teehee this old chestnut again It is most defintiely not anti lag, sorry Moray, anti lag makes popping and banging noises as its fuel exploding in the turbo to keep it spinning, which is why you dont fit it to a road car, not if you want to keep it ont he road for more than 5 minutes without a rebuild anyway. Check the thread Mike mentioned it went on for ages, and i still dont think we got to the bottom of it

Mike Tuckwood

This one also popped up again just before Christmas o a different list, these are the 2 replies that seemed to make the most sense.


1) To the best of my knowledge, WRC cars do not use blow-off valves, because
of the anti-lag systems. The two would constantly be fighting each other.
The "WRC chirp" you refer to is compressor surge, because there is no
blow-off valve.

2) The blow off valve inhibits sharp response when changing gear, hence the
lack of use in the WRC cars, the chirp is the pressure fighting its way back
through the turbo. As WRC Turbos don't have to last that long this does not
matter but ... it puts a lot of shock into the impeller.



The trade-off of course is that the turbo stalls as some of the pressurised
air in the system rushes back through. However the WRC Turbos have specially
designed blades which allow the air to flow back without causing too much
stall (is it this flow-back which causes the chirpy noise rather then the
wastegate?)

Make your own mind up as to the accuracy of the above.

Mike.

WALKER

Cheers Lads

Im still confused though, why would a chipped cossie do it and not my Scoob?
Ive always been led to beleive that it is the wastegate chattering, but the blowing back of pressure through the turbine blades does make sense.
Could it be that a Cossie uses a larger turbo hence amplifying the sound?
Bewildered
Paul

Bob Rawle

The Cossie boys tend to not fit dump valves (bov)so the noise you hear is definatly the boost pressure pulsing back through the turbo.
if you have a car with a cone induction kit then try blocking off the bov return to the air intake and listen (similar noise).
I ran my car for a month like that and the part throttle pick up improved no end. I chickened out and unblocked it eventually but have modified the bov to use a stronger spring so I vent high boost only and still get the good pick up without stressing the turbo bearings.

Bob

WALKER

Cheers Bob
I do have a cone induction kit fitted(HKS), but could you please let me no how to alter the bov If it seems fairley easy ill have a go this weekend . Thanks in advance

Paul

Bob Rawle

I have replied to Paul off list on this one.
Its not a recommended mod for Impreza's although Cossies survive ok. (or seem to)

Bob

WALKER

Cheers Bob
Will give it a blast at the weekend
Thanks for your help

Paul

MorayMackenzie

Ian,

Cars with anti-lag systems don't run blow-of-valves (they are incompatible with the system), so the chirp IS caused (as a side effect) by the anti-lag system (sorry Ian ), along with the pops and bangs you mentioned.

Prodrive would probably not supply an import car with blanking plugs, but I bet the UK owners would be queueing up to spend at least £200 on a "Richard Burns WRC Chirp Enhancement Package"! (Just joking guys! )

Moray
(Filthy japanese import scumbag owner )

Ian Cook

I have mailed Prodrive to ask em what it is, if they reply, that should halt the argument

BTW I wouldnt be interested in the upgrade Moray, bit too max power for me

Allegedly if you fit a sequential blow off valve you can make it sound the same, even if its not the same cause.

[This message has been edited by Ian Cook (edited 28-01-2000).]

MorayMackenzie

Ahh, that'll be the HKS Super Sequential Blow Off Valve I presume, Mr Cook...

Last car had one: Too high pitched without the noise adapter vane. Makes the car sound camp. Funny, all the girls liked it, all the blokes thought it was a bit camp! Oh well, I don't have any interest in impressing blokes!

Not quite the same as anti-lag though. My friends Supra TT sounds quite nice with the Blitz blow off.

I suppose the pops and farts associated with the measured air charge being dumped direct to atmosphere causing fueling problems may sound a little anti-laggy to some...

Moray

Wreckleford

Okay, this is a Subaru bbs, but ...
the Evo IV to VI road cars have some sort of antilag system fitted as well as using a blow-off valve. Anyone know how it works?

WALKER

Thanks for all the replys guys. Still confused though. Great if you get a reply from Prodrive though Ian, that would put it all to rest.
As for bov,s my mates cossie was also running a dumpvalve, so you had the noise of that expelling air on gearchange but also theother noise as well.I tend to agree with Bob that it is air being pulled back through the blades:confused

Ian Cook

No idea Moray, I heard someone saying you could get the chittering noise by fitting a sequential dump valve, but i assume you are correct. I have never really been interested in making my car sound like that, the exhaust is enough for me

Wreckleford

You can get the noise with some of the aftermarket BOVs with adjustable or just stiff springs. What happens is that at low boost (low revs, part throttle)the pressure differential is not enough to force against the spring to open the valve so you get compressor surge (the air flowing back through the compressor). At higher boost, the differential is enough to open the valve and ytou don't get the sound. I woudn't reccomend this though. You might well destroy your turbo and all just to get a sound.The HKS SSBOV does not make thsi sound as it opens t very low as well as high pressures.