Scooby turbo and wastegates

[RB Will]

Right im no good for things of a mechanical nature. I have 2 Imprezas one of which is tuned and i love the dump valve noise but with my other one a standard P1 I would prefer it to make the nicer chattering noise which im led to believe is a wastegate? external wastegate? I dont know, guess some of you guys do, wondering if anyones knows about this as I have never seen a scooby running one its always just dump valves. failing that what is it that makes squeaky whistle noise on the rallycars, I met a guy whose scoob did this and he said it was not dump valve or wastegate just air going back through the turbo if so how the hell did it make that noise and so loud? what work is involved in fitting a different noisy wastegate? cheers guys

[dnb]

I think you're a bit confused on the dump valve and wastegate issue.

A standard Scoob has both wastegate and dump valve. The wastegate is built in to the turbine side of the turbo and vents waste exhaust gasses to regulate the boost. The dump valve is plumbed in to the compressor side and dumps intake air that isn't required (eg on gear changes).

You have the choice of vent to atmosphere or recirculating dump valves. The standard is recirculating, and is quiet, VTA ones make that whoosh noise on gear changes, or if you put a stiff spring in them, they can chatter if you want

All Scoobs have internal wastegates as standard. These are generally quiet so you don't even notice them. If you change the turbo, then you can get an external one and these are a bit more noisy.

[tuttle]

RB Will said:

. I met a guy whose scoob did this and he said it was not dump valve or wastegate just air going back through the turbo if so how the hell did it make that noise and so loud? what work is involved in fitting a different noisy wastegate? cheers guys

'Waste gate chatter' is a bit of a mis-nomer really. That noise of air being forced back through the turbo (described above) is actually what makes that noise, careful, too much can damage it.

[deltafox]

I think youll find the noise your looking for comes from a diaphragm type dump valve rather than a piston type....sounds like a turkey clucking to me....

[greg_D]

the squeaky whistle noise is an anti lag system, a bit hardcore for road cars by all accounts.

i'm not sure how it works btw

[dnb]

You inject fuel during the valve overlap period on gear changes. The fuel passes through the engine and ignites in the turbine housing, driving the turbo.

Great fun, but costly on turbos!

[Power Junkie]

Rally cars run very high boost (around 5bar) they also run with no dump valve, the noise your after is basically the wastegate opening and the turbo stalling. but that with the anti lag is the sound you get. Your stock turbo wont last long doing this, TD05 would last longer than a IHI-Vfxx..

[dnb]

no, the turbo doesn't stall. It runs over-speed as it's got nowhere to pump the air to.

(Put your hand over the end of a vacuum cleaner if you don't believe me. Does the motor go faster or slower?)

[Power Junkie]

ok I stand corrected

[The GMan]

If you go for an external wastegate, stick a screamer pipe on too.

That gives you an interesting noise aswell.

[dnb]

VTA dump valve with added duck whistle anyone?