May be a dumb question, but as this is my first Scoob can anyone describe what this should sound like?

Changing up just under 4,000 rpm, (nearly run in http://bbs.scoobynet.co.uk/smile.gif)I hear what is best described as a growling noise on lifting off. I expected to hear wastegate "chatter" that you associate with turbos - not this!.

Is this normal (car running fine) or could something be wrong?

Cheers
Scottie

Hi there,

The wastegate shouldnt make any noise (virtually)

As for the dump valve, it will depend if its standard, and if you have an induction kit fitted. If its all standard then you shouldnt hear it, it will be quiet and muffled.

With an induction kit you will hear it being "dumped". And if you have a blitz, hks, or any other external (none recirculating) valve, then you will definately hear it! :-)

But it shouldn't "growl"...sure it doesnt sound like someone blowing over a top of an empty bottle ?

J.

Hi,

Its definately not the "blowing over bottle top" noise.

Car is totally standard MY99. It's certainly not an unpleasant sound and may just be induction /exhaust noise (definately a growl) on the overrun/lifting off particular to flat 4 engines that I'm not used to. (has done it from new).

Car seems to be running fine generally. Just want to be sure that if I mention it to the dealer at the first service and he says "they all do that" that he's right.

Scottie

Hi again,

Its hard to say without hearing it.

See what the dealer says, then if ya still not sure, take it to another.

Dont mention it..see if they pick it up... If they dont, they comment about the noise.. http://bbs.scoobynet.co.uk/wink.gif

J.

I have noticed this 'blowing over bottle top' sound on my93 WRX under hard acceleration.Could it be a sticking actuator?
The car goes well, but any suggestions if this is not normal would be appreciated.

cheers Chris.

firefox: are you one of the MiB?

M.

Scottie

My MY99 had exactly the same problem - it was caused by clutch pipes vibrating against the bulkhead. If you can feel a vibration through the clutch pedal as you change gear, this is probably the cause of the noise.

Steve
T686 EDP

Where are my shades.... http://bbs.scoobynet.co.uk/wink.gif

Hows it going Malique ? Got any aliens for me to shoot ? LOL

J.

Hi Chris,

The problem with the "blowing over an empty bottle" noise is well documented on the FAQ.

It was a design fault, although I have never heard of it on a 93WRX.

Check out the FAQ for more info - I need sleep.

J.

I have a STI V Type R. The standard Dump valve is totally silent, even under hard driving.

I have been told to change it to one that vents to atmosphere to improve response and keep the boost more consistent.

Should we change the standard BOV?

Hi there,

The BOV on a version V is a far better design to previous BOV's. It can easily handle the pressure and has a faster acting mechanism.

Personally I would keep the original BOV. It works perfectly.

The only reason a person would want to change it to an external one, is possibly for looks and noise - I dont think an external would give any better performance results.

J.

ps - The gains from a BOV are very minimal - Again, you will only notice the benefits if you are running high boost or perhaps a uprated turbo. Most these so-called GrpA BOVs you see on R5's are crap and dont actually produce any performance increase. I would either go for a HKS, Blitz, Greddy, or perhaps the new Baily piston type one ?

[This message has been edited by firefox (edited 09-09-1999).]

Hi Firefox,

Cheers for that.I'll get it sorted.

fire fox

whats the "blowing over the bottle sound" is it the same with a WWII air raid siren? I can hear it on the right side of my car (turbo probably) and it happens when I boost, at high rpm around 4500 you wont hear the whinne could it be the impeller?

We have ahad a number of problems with standard valves leaking small amounts of boost off early.

This is the reason we have high pressure piston type valves, especially for the STi5.

Like the mixture of staff we have here, you can have a quiet one or a noisey one!

Dave,

How many cases of "leaky" dump valves have you had ?

As far as I was aware they were a great improvement over previous designs (quite a few other people in Japan I speak to have agreed).

I agree if its a one-off faulty valve and the cost of replacing it with an original is the same cost as an aftermarket one, then I'd go for a Japanese aftermarket one.

J.