What's with this whoooo noise in VWs these days

Packrat

For the second night recently I'm staying in a b&b overlooking a car park frequented by the loud exhaust, laps of the town type idiots. This is bad enough, but whats really driving me insane is this one cnut in a golf which makes this whoooo noise every tome he changes up from first to second. Last week it was one in a passat which made exactly the same noise changing down as well as up.
Ive never noticed this noise before, and I wore out a few VWs 20 years ago...

So, - clutch? Dmf? What?

Sobanek

SOME SERIOUS BOOOO OFF HER LAD

Toyotafanboi

give 'er shoe and make 'er cooooooooooooo!

Packrat

Sobanek wrote: »

SOME SERIOUS BOOOO OFF HER LAD

Toyotafanboi wrote: »

give 'er shoe and make 'er cooooooooooooo!

I ought to have known. Dont ye have school in the morning?

Big Nasty

D1cks in Diesels is the new Pr1cks in Civics

D_turbo

Usually Its when the Cat is replaced with a straight pipe.
Giving it that terrible Boo sound.

Maybe other ways of doing it, but thats how the Vag brigade around here do it

Toyotafanboi

Packrat wrote: »

I ought to have known. Dont ye have school in the morning?

yes, it's the first day of my second last semester, thanks for asking

personally i'm not a fan of the sound, or diesel german motoring in general. i generally cringe on behalf of the lads driving them. particularly as the cars themselves are all show, no go. slow as **** yokes.

Chimaera

It's the sound of the turbo as it comes off boost. It's usually only audible in cars that have had the resonator and silencer removed - the cat doesn't have to be removed.

131spanner

€10 says that Golf has a Nurburgring or Van Aaken sticker, JOM coilovers, a letterbox exhaust or mad big mud-flaps.

Sobanek

Packrat wrote: »

I ought to have known. Dont ye have school in the morning?

Ah jaysus I wish. Finishing work at 8AM

I miss school

Chimaera

Chimaera wrote: »

It's the sound of the turbo as it comes off boost. It's usually only audible in cars that have had the resonator and silencer removed - the cat doesn't have to be removed.

Resonator and silencer removed? Silencer as in backbox? Are you sure?

Dermighty

Trapped owls in the cylinders

Chimaera

Augeo wrote: »

Resonator and silencer removed? Silencer as in backbox? Are you sure?

Resonator is the middle box, silencer at the back.

Tail Docker

What you are hearing is the gasps of admiration from the chung wans at the slickness of the gearchanges. And the power. "Woooo...Wooooo!" The Beors love a rapih daysul.

Dartz

Renault 1.5 DCi's will do it too. At least the one in the old Scenic did it. Was really noticeable. Did it constantly when the wastegate jammed open.

BMJD

It's supposed to be a dump or blowoff valve. More likely to be a simulator which is saaaaaad and should result in instant and severe beating of offenders.

Moneymaker

It's the sound of my ever fading hope for the future of humanity slipping away.

YbFocus

It's the sound of the internal wastegate, you can't hear it until the exhaust is derestricted.

Stupid and sad thing to do, makes them look like children.

Kimbot

Its this guy been held captive in the boot :P

alias no.9

It's the sound of disappointment as the extremely brief surge of power has ended

Ded_Zebra

The sound is a turbulent surge of air as the waste gate opens in the turbo. Manufacturers spend a great deal of time and effort designing exhaust systems so the sound of it is absorbed and not audible. It can be made audible by removing all of the resonators and silencers on the exhaust as mentioned above.

Personally I don't mind the sound however, it has come to be associated with gee bags and morons so most other motoring enthusiasts will say they hate the sound by extension of the people it is associated with.

dgt

DZ has it in one, its just a bit of turbulence as the gate opens under lift off

A vnt has a more pronounced sound

They'll all do it if a busted exhaust is involved, good example is the 2nd generation Avensis

Ded_Zebra

dgt wrote: »

DZ has it in one, its just a bit of turbulence as the gate opens under lift off

A vnt has a more pronounced sound

They'll all do it if a busted exhaust is involved, good example is the 2nd generation Avensis

Do you know Why a VNT does it more? I never managed to work that out.

dgt

Ded_Zebra wrote: »

Do you know Why a VNT does it more? I never managed to work that out.

Instead of one gate with a flapper a vnt has a series of moving levers which allows a better controlled airflow. Plus as most vnt's are electrically actuated, that leaves it much more noticeable both in terms of pitch and loudness

George Dalton

dgt wrote: »

Instead of one gate with a flapper a vnt has a series of moving levers which allows a better controlled airflow. Plus as most vnt's are electrically actuated, that leaves it much more noticeable both in terms of pitch and loudness

The majority of VNTs are vacuum operated

dgt

George Dalton wrote: »

The majority of VNTs are vacuum operated

I'm thinking of something else here....

Apart from that blooper though

Chimaera

Variable Nozzle and wastegate are two different means of controlling a turbine. Blow-off valves control the compressor.

It might be useful to go back a little first though and explain the basics of a turbocharger for the uninitiated. There are two basic components in a turbo, connected together by a shaft: the turbine and the compressor. The turbine is driven by exhaust gases leaving the engine causing it to rotate; this rotation spins the compressor which compresses air coming in through the intake. Outside of a small number of operating points there's likely to be a mismatch between the energy supplied by a fixed turbine and that needed by the compressor, so we need to control the output of the turbine in some fashion.

A turbine has a rotating wheel and a set of guide vanes in the housing that direct gas onto the turbine at the correct angle to make it spin. The cheapest (and for a long time only) way to build a turbine was with fixed guide vanes. So it'd perform at a fixed level for a given gas flow; it'd also only work optimally at a certain level of flow. In this setup, the turbine output is controlled by a wastegate: this is a bypass valve that allows some portion of the exhaust gas to bypass the turbine entirely and reduce the gas flow through it, thus reducing its output. In the past the wastegate would be controlled by a line coming off the compressor housing: as boost levels increased, the wastegate would open more to reduce output; the limit would be set by something like a Dawes device or other mechanical means. Newer cars use a solenoid valve controlled by the ECU to vary the wastegate opening. The whole thing is rather crude, but it works well enough.

More recently some crafty bugger realised you could more carefully control the output of a turbine by controlling the guide vanes and the concept of the variable nozzle or variable geometry turbine was born. This system uses an actuator to adjust the angle of the guide vanes relative to the turbine. It allows more precise control of the turbo output, while also increasing efficiency in the turbine across a larger range of operating conditions.

Blow-off valves are rarely used in roadgoing applications but since they were mentioned, it's worth discussing them. A blow-off valve releases pressure from the compressor housing. Why are they needed? If the engine suddenly goes from full load to no load, such as lifting off completely after hard acceleration, there can be a lot of pressure in the compressor housing which now has nowhere to go. This can cause damage to the compressor and other components downstream. This is usually a bigger problem for petrol engines where a lift-off also results in the throttle being closed. In a diesel engine without a throttle, the pressurised air can continue into the engine and pass through the cylinders as normal. The blow-off valve (where fitted) is there to limit pressure inside the compressor housing.

Going back to the main point in this thread, the "whoo" noise comes from variable nozzle turbos as a result of the vanes suddenly moving back to the low output position and creating turbulence around them while doing so. In a wastegate I imagine it could happen from exhaust whistling through a wide open wastegate.

jimgoose

Sobanek wrote: »

SOME SERIOUS BOOOO OFF HER LAD

Toyotafanboi wrote: »

give 'er shoe and make 'er cooooooooooooo!

Daycint bah, puuure daycint! :pac::pac::pac:

Bpmull

Some vw diesel stuff does it slightly from the factory. For example 1.9 tdi golfs make the noise the odd time depending on what way your driving it. It's not the really loud noise that some are set up to make. But if you accelerate hard in 2nd 3rd and lift of quickly you'll get the noise. I think some model d4d avensis are like that. I don't think there is anything really wrong with the noise but the ones that are set up to be loud I don't like just stupid and pointless IMO.

Packrat

Jesus Christ, I actually thought there was something wrong with the cars, but no, it seems it's the owners. I actually used to be into fastish cars about 20 years ago...getting old sucks.

I like diesels these days, nothing better than a big luxobarge in either petrol or diesel, all the better if its a Rangerover or Amazon.

When I see one of those nurburgring stickers I die a little inside. More "Ass monkey" than Gas monkey methinks. Sad sad fcukers.

If the noise is heard as backbox and resonator are removed how are the cars so quite except for the coo sound?

dodderangler

Bring back the jap cars!!!

Chimaera

Augeo wrote: »

If the noise is heard as backbox and resonator are removed how are the cars so quite except for the coo sound?

A turbo is pretty good at silencing the exhaust on its own.

djflawless

Absolutely horrible f#ckin noise.has turned me off VW's tbh.
Bora's,passat's,golf's,Audi's are the same as ek civics were 5 years ago
And instead of the bang of vtec laaaad, all the lads in zee germin cars are shoving pigeons up their exhausts
Also, not sure how exactly, a diesel mechanic told me before its shocking hardship on a turbo


Turbo whistle and anti lag ftw!!!

131spanner

dodderangler wrote: »

Bring back the jap cars!!!

Some day... Hopefully

I almost lost all hope when a friend of mine (supposedly big into his cars) genuinely thought JDM stood for Japanese Drift Machines. I cried inside a bit.

Chimaera

Chimaera wrote: »

A turbo is pretty good at silencing the exhaust on its own.

'tis a wonder manufacturers bother with silencers so

Roger Mellie Man on the Telly

Please tell me this noise can't happen with a turbo petrol (I have a Mk5 gti)?

If I go into the country I inevitably get tailed for a while before being overtaken by a Passat or A4 with hid's/RS4 badge/etc. followed by a plume of detritus and sinking rear shocks when he changes up. In fairness they probably have more torque than my little tfsi.

djflawless

Roger Mellie Man on the Telly wrote: »

Please tell me this noise can't happen with a turbo petrol (I have a Mk5 gti)?

If I go into the country I inevitably get tailed for a while before being overtaken by a Passat or A4 with hid's/RS4 badge/etc. followed by a plume of detritus and sinking rear shocks when he changes up. In fairness they probably have more torque than my little tfsi.

AFAIK tis only diesels that can, bar you want to kick out your cat for "daycent sounds"

Joe Doe

It sounds like the equivalent practice of sticking lollipop sticks in the spokes of your bmx/chopper, back like when you were eleven or so.

These electric powered yokes are the polar opposite problem, virtually silent, but with high torque.
So tour de Irelandes, get some very good lights on your bikes, and loose the dre'beats before the dark days set in...

Chimaera

Augeo wrote: »

'tis a wonder manufacturers bother with silencers so

As good as a turbo might be at silencing, it's not enough on its own. The noise you get from an engine is wasted energy in the exhaust flow. Since a turbo is using up a bunch of the energy from the exhaust it has less energy leaving it, and less noise. A turbo also smoothes out the pulses from the cylinders a bit.

jca

Packrat wrote: »

For the second night recently I'm staying in a b&b overlooking a car park frequented by the loud exhaust, laps of the town type idiots. This is bad enough, but whats really driving me insane is this one cnut in a golf which makes this whoooo noise every tome he changes up from first to second. Last week it was one in a passat which made exactly the same noise changing down as well as up.
Ive never noticed this noise before, and I wore out a few VWs 20 years ago...

So, - clutch? Dmf? What?

It's the dump valve on the turbo. When the revs and boost pressure build up and the throttle is suddenly closed when changing gear the pressurised air in the engine needs to be released. Normally this dump valve is plumbed back into the induction system to keep it silent but these jokers have them venting into the open air with a noise maker on the end to increase the effect. It has nothing to with the exhaust system.

Chimaera

jca wrote: »

It's the dump valve on the turbo. When the revs and boost pressure build up and the throttle is suddenly closed when changing gear the pressurised air in the engine needs to be released. Normally this dump valve is plumbed back into the induction system to keep it silent but these jokers have them venting into the open air with a noise maker on the end to increase the effect. It has nothing to with the exhaust system.

No it's not. I suggest you go back to my post hereexplaining this in detail.

68 lost souls

I nearly died with Laughter at a lad I saw out at lunch this week. Making this noise repeatedly driving through the town with his mates in the back, yellow fogs, tow loop through the number, tints and I think some sort of body kit on a rather fetching seat Alhambra

jca

OSI wrote: »

I prefer my VW to parp to be honest. Whooo was so 2 years ago.

Morris Minor's parp with style:D

jca

Chimaera wrote: »

No it's not. I suggest you go back to my post hereexplaining this in detail.

It explains how fixed vane and variable turbos work(kind of),and, as an add on at the bottom,a very very brief and vague reason for the cooo noise. If I'm wrong I'm wrong but your lengthy tome doesn't enlighten me much. I'll ask the boy racers what they do.

jimgoose

jca wrote: »

Morris Minor's parp with style:D

I tell you this - I encountered a 1974 Granada lately with the 3l Essex V6 and automatic transmission. When it started up and moved off, I was struck by how quiet it was. I kid you not I've never heard anything run as quiet, and here I include my own Jag. Progress??

jimgoose

jca wrote: »

It explains how fixed vane and variable turbos work(kind of),and, as an add on at the bottom,a very very brief and vague reason for the cooo noise. If I'm wrong I'm wrong but your lengthy tome doesn't enlighten me much. I'll ask the boy racers what they do.

In short, most of them run straight-through pipes which releases the daycint boo lad from these variable-vane turbochargers. Some use electric mock-boo wastegate simulators, which can be got from Amazon and various 'Felty Emporia.

jca

jimgoose wrote: »

I tell you this - I encountered a 1974 Granada lately with the 3l Essex V6 and automatic transmission. When it started up and moved off, I was struck by how quiet it was. I kid you not I've never heard anything run as quiet, and here I include my own Jag. Progress??

How quiet would that Essex engine be if it was doing 12-15,000 miles a year? But I understand what you mean there's nothing like a big lazy V6 whispering along no wonder they were the undertakers favourite.

jimgoose

jca wrote: »

How quiet would that Essex engine be if it was doing 12-15,000 miles a year? But I understand what you mean there's nothing like a big lazy V6 whispering along no wonder they were the undertakers favourite.

They're properly strong, them - the block and crank was designed to run a diesel version that never actually materialised. One side-effect of this is the large journal bearings, revving the ballacks out of them causes problems with bearing surface speeds. You would however go through three sets of feeler gauges per anuum keeping them nice and quiet.

jca

jimgoose wrote: »

They're properly strong, them - the block and crank was designed to run a diesel version that never actually materialised. One side-effect of this is the large journal bearings, revving the ballacks out of them causes problems with bearing surface speeds. You would however go through three sets of feeler gauges per anuum keeping them nice and quiet.

I thought the cologne V6 was the good one and it was the Essex that was a bit ropey. The Essex having inherited that stupid distributor drive that was used in the 1.7/2.0 V4. that the Corsair was landed with.

jimgoose

jca wrote: »

I thought the cologne V6 was the good one and it was the Essex that was a bit ropey. The Essex having inherited that stupid distributor drive that was used in the 1.7/2.0 V4. that the Corsair was landed with.

IIRC the plastic timing gears in the Essex used to deform slightly and cause all kinds of weirdness. Easily sorted with good, modern aftermarket ones.