Boost Noise on a Impreza WRX
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Time for a noob question... !
I'm interested in buying a facelifted/'blobeye' Impreza WRX and I took a test drive in one yesterday. It was the first time I've driven a turbo car and I was quite surprised by the amount of noise the turbo made in boost. From around 3000 rpm the car made a very obvious 'wooosh' noise and took off for the horizon. When changing gear at high revs it also made a 'pssst' noise which I assumed was boost being vented.
Is this normal for a standard WRX? I quite liked the sound but I would have thought Subaru would have toned it down a bit.
I'm interested in buying a facelifted/'blobeye' Impreza WRX and I took a test drive in one yesterday. It was the first time I've driven a turbo car and I was quite surprised by the amount of noise the turbo made in boost. From around 3000 rpm the car made a very obvious 'wooosh' noise and took off for the horizon. When changing gear at high revs it also made a 'pssst' noise which I assumed was boost being vented.
Is this normal for a standard WRX? I quite liked the sound but I would have thought Subaru would have toned it down a bit.
Fantastic isn't it? 
Hard to say whether or not the noise you heard is 'standard', but you will certainly hear the turbo spooling and the blow off valve venting on a gear change even on a standard car.
A fairly popular mod is to remove the 'snorkus' (basically some plastic baffling on the intake designed to reduce noice) http://www.scoobymods.com/intake_silencer_removal-... This makes the turbo spooling sound and blow off valve much more noticeable, so it's possible the car you drove had this done.
A 'pod' air filter will make the spooling noise much louder, and a externally venting blow off valve (illegal I believe) will make the venting noise on a gear change quite loud.
Hard to say whether or not the noise you heard is 'standard', but you will certainly hear the turbo spooling and the blow off valve venting on a gear change even on a standard car.
A fairly popular mod is to remove the 'snorkus' (basically some plastic baffling on the intake designed to reduce noice) http://www.scoobymods.com/intake_silencer_removal-... This makes the turbo spooling sound and blow off valve much more noticeable, so it's possible the car you drove had this done.
A 'pod' air filter will make the spooling noise much louder, and a externally venting blow off valve (illegal I believe) will make the venting noise on a gear change quite loud.
The first time I drove a car with a proper turbo on it I noticed the spool up noise from the turbo, I'm used to it now though so it's passengers that notice it more than me. The standard CBV should only really make a slight chuff noise. It's not a great idea to replace the CBV with a BOV on a car with a "closed" air circuit ie one that uses a MAF sensor.
Edited by Syndrome on Thursday 26th November 12:31
Thanks for the replies guys. Being new to this it's difficult to know what is normal and what isn't.
I've had another chat with the dealer today and it turns out that the car does have an aftermarket air filter installed. They are going to put this back to stock as they don't normally sell modified cars. While I agree it does sound great I think this is the sensible way to go. From what I've been reading a 'pod' filter does have some significant disadvantages. Hopefully not all of the noise will go away!
So I suppose the question now is to do I accept the dealers word that nothing else has been changed or do I look elsewhere...
I've had another chat with the dealer today and it turns out that the car does have an aftermarket air filter installed. They are going to put this back to stock as they don't normally sell modified cars. While I agree it does sound great I think this is the sensible way to go. From what I've been reading a 'pod' filter does have some significant disadvantages. Hopefully not all of the noise will go away!
So I suppose the question now is to do I accept the dealers word that nothing else has been changed or do I look elsewhere...
blackNBUK said:
Thanks for the replies guys. Being new to this it's difficult to know what is normal and what isn't.
I've had another chat with the dealer today and it turns out that the car does have an aftermarket air filter installed. They are going to put this back to stock as they don't normally sell modified cars. While I agree it does sound great I think this is the sensible way to go. From what I've been reading a 'pod' filter does have some significant disadvantages. Hopefully not all of the noise will go away!
So I suppose the question now is to do I accept the dealers word that nothing else has been changed or do I look elsewhere...
As long as its half decent filter, keep it! Enjoy the sound.I've had another chat with the dealer today and it turns out that the car does have an aftermarket air filter installed. They are going to put this back to stock as they don't normally sell modified cars. While I agree it does sound great I think this is the sensible way to go. From what I've been reading a 'pod' filter does have some significant disadvantages. Hopefully not all of the noise will go away!
So I suppose the question now is to do I accept the dealers word that nothing else has been changed or do I look elsewhere...
Changing the Dump Valve is not Illegal, but there are mixed views on what the effects are of the fueling. Some say it doesnt make a difference other say that it does.. My personal view is that it does not affect the the car in one bit on the performance side it is purely down to the noise.
The standard air box is good upto about 400Bhp with a good panel filter, but you will need a cone filter for maximum induction noise.
The standard air box is good upto about 400Bhp with a good panel filter, but you will need a cone filter for maximum induction noise.
Sounds like this WRX may have had some mods done to it. It's always good to do your own but if they've been done properly you should just enjoy.
VTA BOV's/Dump Valves are of no use until such time as you need one. You would soon get fed up with the noise and as for performance it does have an affect on fuelling and makes for jerky and sometimes violent gear changes.
The standard recirculating Air Bypass Valve does an excellent job to well over 400bhp+ and coupled with a good flat panel air filter and Snorkus Delete modification you should hear enough of a gentle ppppssssshed for sufficient personal gratification without the whole world having to hear it as well!!
VTA BOV's/Dump Valves are of no use until such time as you need one. You would soon get fed up with the noise and as for performance it does have an affect on fuelling and makes for jerky and sometimes violent gear changes.
The standard recirculating Air Bypass Valve does an excellent job to well over 400bhp+ and coupled with a good flat panel air filter and Snorkus Delete modification you should hear enough of a gentle ppppssssshed for sufficient personal gratification without the whole world having to hear it as well!!
I'm ashamed to say I've barried my STi with a dump valve - I know it's probably not the best thing to do to it, but I love the pppssschhh sound it makes (I did grow up to Fast and Furious though... think the 2F2F Skyline was my first poster car). If I get fed up with the sound I just stay off boost for a while - and hey, that helps at the pumps!
That plastic turbo silencer thingy seems to be quite a common thing to do. Not entirely sure if it gives any performance benefit (probably not) but yeah the whistle is extremely noticeable.
I also like the way you can faintly hear the gearbox in third, although this probably means it's going to pop soon.
That plastic turbo silencer thingy seems to be quite a common thing to do. Not entirely sure if it gives any performance benefit (probably not) but yeah the whistle is extremely noticeable.
I also like the way you can faintly hear the gearbox in third, although this probably means it's going to pop soon.
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