Downpipe Questions
 

I just had an open mouth stainless downpipe fitted and WOW! what a difference it pulls much harder and boosts much earlier.

My question is I have a Bailey dump valve on the car, when I shut off the gas I get the rally chirp noise and then immediately after it dumps through the d/v. Does this mean my d/v is opening too late and my turbo is stalling?

I never noticed this before my downpipe was fitted is this just because the standard pipe is not masking the noise?

By the way I know the risks of running a VTA d/v and I like the noise please don't turn this into a d/v are for Chavs thread :lol1:

Thanks very muchly

you'll find out when your engine munches on parts of your compressor blades..

seriously, what model scoob, what year, what turbo blah blah and you are probably better of posting this in Technical otherwise prepare yourself for the likes of PS Lewis et al

The car is a MY00 classic, so it will probably be the smaller D04 turbo I believe but not certain so it won't take much if it is stalling.

It doesn't seem to make the noise then im really flooring it but not sure if the noise of the d/v is masking the chirping sound. I might put the standard recirculating valve back on and see if I still get the noise.

Had a bailey vta on my classic for 21,000miles mate i wouldnt worry about the dumpvalve itself-has your car got a front mount intercooler on it????just wondering if the position of the dumpvalves the problem.

By the way the "rally chirp noise" is known as turbo wastegate chatter mate though on later scoobys with direct mount to intercooler dumpvalve you dont get the noise at all or shouldnt theres about 5 of my mates got various scoobs an none of us get wastegate chatter.

Yes it's the direct mount to intercooler type dump valve.

I don't mind the noise at all in fact I love it however if my engine decides to eat my turbo then I wont be so keen lol.

suppose the dumpvalve could be sticking hence the wastegate chatter in my experience(so far) ive only known chatter to be noticeable when running no dumpvalve at all.

Its just strange, ive got a my00 myself with bailey vta dumpvalve, full decat afterburner system, basically the same stuff as you-maybe ur dv is faulty.

hi Dave the chirpping sound often referred to as 'wastegate' chatter is the sound of the air rushing back into the turbo on closed throttle causing the compressor blades to stall.

There may be DV component here and as Davvo suggested, he should change the DV

cheers mate :notworthy

Tut tut Dave should know better my friend.;)

I will put my standard recirculating valve on tomorrow and see if this sorts out my problem, whilst its off I will strip and clean my Bailey one maybe this will help.

By the way I knew this was not wastegate chatter as I read somewhere in another post thats why I referred to it as rally chirp sound lol.

Thanks very much guys :)

lol dan ay up mate thats what 99% of ppl would have called it:lol: i didnt claim to know what caused it:D varboy said its what ppl referred to it as, even though it dont involve wastegate:hjtwofing

so indirectly to summarise-it aint very often im wrong but im right again :lol1: :lol1: daaaaaaaaaaam:luxhello:

brief description nicked from another scoobynet post

Wastegate Chatter Myth
There is a common myth in the automotive world about so called "wastegate chatter", a noise created on lifting off the throttle in a turbocharged car. The sound is commonly described as a chipmunk or a rattlesnake and is often stated incorrectly as being a result of the turbo's wastegate closing.

The noise is in fact the air compressed by the turbo passing back through the compressor housing of the turbo after having hit the now closed throttle plate.

A BOV (Blow Off Valve) will usually eliminate this noise, but in some cases, i.e. where the BOV doesn't open fast enough or is setup to only react to high boost, some chatter will remain.

The chatter noise is very noticable on WRC Rally cars, where no BOV is allowed.

As this doesn't seem to make this noise on full boost I really shouldn't worry as I guess this won't be putting a massive load on the turbo then?

I think this has been doing this all the time but it has just become more apparent now I have put a stainless downpipe on and you can hear it more.

Is this the first post about VTA Dump Valves on ScoobyNet that hasn't turned into a "we all hate dump valves thread" lol?

I had this this problem on MY99 with a bailey DV10 after I degreased my engine bay, the valve was sticking and needed a little grease to open quick enough.

Quote "Is this the first post about VTA Dump Valves on ScoobyNet that hasn't turned into a "we all hate dump valves thread" lol?"

wait till P.S.lewis reads it though to be fair i dont mind i like a laugh.

Bailey are ****.

lol cheers for that i got told forge were too:thumb: but werent about to spend nearly twice as much on something to do the same job ie turbosmart blitz hks etc.

So do open neck downpipes help the turbo spool up lower in the rev range?

how does this affect performance (torque/hp) higher in the rev range then? does the turbo 'top out' earlier too?

thanks :)

if by open neck you mean minus the silly blanking plate over the wastegate and with a high flow cat or no cat at all then yes spool will be improved as there is less back pressure from the exhast system preventing the turbine wheel from spinning.

Torque/HP is improved throughout the rev range due to higher boost levels.

Not sure what you mean by the turbo 'topping out'

I assume by topping out you mean hitting full boost then yes, I am well impressed with the performance and sound this has given the car, it just seems less restricted revs more freely if you know what I mean.