What causes this sound?...

[tjw2007]

There's a guy who drives past me like a maniac every morning when I'm on my way to work and everytime he changes gear there's a sound like a loud hydraulic piston, it seems to be when he puts the clutch down. He's obviously 'modded' his car quite a lot and it seems really fast - so was just wondering if anybody might know what causing this sound?

Cheers.

 

[Izo Azlion]

Its a Blow Off Value, or "Dump" valve.

This occurs as air builds up to be used by the Turbo, and as he changes gear its "blown off" or "dumped."

It can be done much more silently but some of them make a pretty nice sound.

That said, there are lame ass speakers you can get put inside the bonnet, which will make the same sound every time you shift gears.

What car is it, out of curiosity?

 

[Hansi]

I've allso heard about air supported transmission which might make this sound but I don't even know if that really excists. It is most likely a blow off valve I think

 

[HDi fun]

air suspension was known on some of the Merecedes Benz S class models. This could make similar noises to those you describe.

 

[obi_waynne]

I'd be interested to know what sort of car it is. It does sound like a dump valve to me. Only really works on turbos and some modern turbo engines dont appreciate the "lost air pressure."

 

[tjw2007]

I'm not sure, but I think it's a Subaru Impreza - but it looks like quite an old one. The noise is really loud though, like those hydraulic brakes you get on buses and lorries.

 

[ascaudio]

definatly a dump valve ona scooby lol

 

[billyo]

Do you know there is a virus code in your website ascaudio?

I get this message :- The requested object is INFECTED. The following viruses Trojan-Spy.HTML.Fraud.ce were found

Probably means you've been hacked.

 

[HDi fun]

Lorries and buses generally use air brakes. Cars use hydraulic ones.

 

[obi_waynne]

(Derailing this thread - sorry!) Are there any benefits to air brakes? I would have thought hydraulic brakes would work better on everything buses included.

 

[HDi fun]

Air brakes do introduce a delay in response. Their use on railways and artics is because you can couple and decouple units, tractors, trailers etc. without having to bleed an hydraulic system.

I also think that the tractor units on lorries are braked hydraulically with the air system reserved for the trailer.

On rigid vehicles I, too, cannot see the advantage, unless it's to do with having some sort of failsafe system.

 

[claymore]

the brakes are permanently on, on a lorry the air actually releases the brakes, so if you run out of air, your brakes come on, on another note, i'm a bit surprised that someone signed up to this forum doesn't know what a dump valve sounds like, no offence intended

 

[pgarner]

im informed by the wife that her fathers trailer doesnt have the air brake connected to the main brakes its on a separate lever. the hydraulic brakes are still on on the wagon itself.

theyre are many people who dont know what the dump valve sounds like have a search through the forum theres plenty off people asking how to the woosh noise for their own car.

 

[HDi fun]

I have a grasp of the reasons behind fitting a dump valve when it comes to performance on turbocharged petrol engines, which is to stop back pressure when the throttle is suddenly closed. This prevents the turbo from stalling, giving smarter response when throttle is next applied (eg. after a gearchange).

Therefore, I assume that they're not used on diesel engines as there's no throttle.

Is there any way to make a dump valve quiet without reducing its effectiveness?

 

[claymore]

I have a grasp of the reasons behind fitting a dump valve when it comes to performance on turbocharged petrol engines, which is to stop back pressure when the throttle is suddenly closed. This prevents the turbo from stalling, giving smarter response when throttle is next applied (eg. after a gearchange).

Therefore, I assume that they're not used on diesel engines as there's no throttle.

Is there any way to make a dump valve quiet without reducing its effectiveness?

you can fit a recirc valve which does the same job, but instead of dumping to the air it dumps back into the inlet side of the turbo or supercharger

 

[HDi fun]

To Glaymore:

Thanks, that seems to be quite a novel approach. Is there any benefit doing this with a diesel engine? I'm happy to consider minor physical mods if there's a benefit.

 

[claymore]

To Glaymore:

Thanks, that seems to be quite a novel approach. Is there any benefit doing this with a diesel engine? I'm happy to consider minor physical Modifications if there's a benefit.

the reason for a bov is to releive pressure as the throttle butterfly is shut, as you dont have a bytterfly on a diesel i think it would be pointless, but don't quote me on this, i'm not that much of an expert

 

[pgarner]

Hdi you can fit dump valves / recicuating valve to a diesel engine but it takes a lot of work and mods. and i dont think you get any better preformance

 

[pgarner]

HDI have a look at
http://www.zen19051.zen.co.uk/prod01.htm
cant see the 2.2 406 on their list but the 1.9s there so they might do one

 

[HDi fun]

They don't list the 2.2 HDi engine. The 1.9 is the XUD unit which is very different.

Do you think there's a benefit for me if I fitted a dump valve to my car?

Or should I just keep the accelerator down hard during upchanges?

This is really a needless question because I don't find the 2.2 with a custom map to be underpowered.

But (even at my age ), I'll take more

 

[pgarner]

i wouldnt bother had a look and another forum suggested using the £300 to buy uprated injectors as the valve only made a sound. i wouldnt think any performance would be benefited it

 

[HDi fun]

I'm thinking that I might need to get the injectors replaced at some point. They get a right royal bashing in HD engines, remapped or not. Perhaps reconditioned or remanufactured ones would be a good way to keep the costs down.

 

[obi_waynne]

Get yourself a panel air filter if you haven't already - they are washable so last forever and you will get marginally more top end power from it. Do you run an injector cleaner through it from time to time?

 

[HDi fun]

Still using Peugeot OEM filter to comply with warranty t's and c's.

I do run Forte Diesel Treatment though it every couple of months and I always use premium fuel.

Quite often use Millers Diesel Sport additive which is said to help look after injectors

 

[obi_waynne]

The 900bhp (ish ) remap doesn't count as a mod with the T&C's wheras a washable direct replacement air filter does? Crazy town!

 

[pgarner]

why not get the filter or even a proper induction kit for it. if the car has to go into the garage just put the old airbox back in

 

[HDi fun]

For insurance purposes the remap is a mod, and they're aware of it> clearly I've only told them its 190ish bhp, not the full 900

For warranty it's in factory 136bhp tune as far as Peugeot is concerned. And they've not noticed during the 45,000 miles it's been in remapped tune. Although one technician who drove it on a quick test drive did comment discreetly to me in the waiting area that 'there's no way that car's standard.'

 

[Izo Azlion]

For insurance purposes the remap is a mod, and they're aware of it> clearly I've only told them its 190ish bhp, not the full 900

For warranty it's in factory 136bhp tune as far as Peugeot is concerned. And they've not noticed during the 45,000 miles it's been in remapped tune. Although one technician who drove it on a quick test drive did comment discreetly to me in the waiting area that 'there's no way that car's standard.'

Wait what? 900bhp?

WTH are you driving? A ****in F-22 Raptor? Haha Have I been here this long and totally misinterpreted what kind of car you have?

 

[HDi fun]

No, I'm only kidding - it is about 190bhp.

It's Waynne's post where he's questioning the sense of warranty T's and C's that allow a remap without question but won't allow you to fit a high flow panel filter allied to my trademark sarcasm.

 

[obi_waynne]

Sarcasm, now there is a high form of wit!

We were just kidding - I did exaggerate a bit. I might have said 187bhp and got into a major row with HDI so I thought it best to play safe

 

[Izo Azlion]

Damn my gullibility.


Mine'll be up closer to that in the next two weeks. Taking it out to Votex to get it Revo'd

 

[obi_waynne]

Is that a switchable remap? I'd like to hear your comments of the revo remap. (I [presume you mean 900bhp? )

 

[pgarner]

All revo remaps are switchable as far as im away you just need to get a port switch to change. does cost another £150 thou

 

[HDi fun]

Waynne, I'm not really all that nasty. And I do rely upon sarcasm to get me through. Blimey, I drive a diesel and even like it. That's quite sad really. In the big scheme of things.

TO be totally honest I'd rather dump the lively Pug, dump the Seat D thing and move me, wife and kids to a patch of land in the middle of nowhere.... operate a farm smallholding, do some private contract work and live off the land year in year out.

I;m not even that interested in biodiesel really.

hdi (Paul Anderson) has had enough and more of the crap that British living brings.

 

[obi_waynne]

I was being sarcastic too Paul

I've got to agree with you there Paul. I'm all for going "back to basics". I've just bought a couple of fruit trees and we are going to start to grow our own food. I've not bought a ready meal for 3 years. We seem to spend too much time supporting a frustrating lifestyle in this modern rat race.

 

[Izo Azlion]

Is that a switchable remap? I'd like to hear your comments of the revo remap. (I [presume you mean 900bhp? )

Yeah. I'll be getting the Select Switch too, its not cheap but frankly for the ability to turn it off/not worry when it goes in for its service, makes it all fun. The Select switch may have to wait a month (I cant fork out all that kind of money at once without screwing my living costs, haha)

Looking forward too it though.

I'll let you know how I get on with my 900bhp GT TDI Sport, hahaha

 

[pgarner]

izo look for them on ebay i got a sps2 ( has 95 and 98 ron swiches and anti theft ) for £30 and made sure it works now just have to get the car in for the map

 

[pgarner]

Waynne, I'm not really all that nasty. And I do rely upon sarcasm to get me through. Blimey, I drive a diesel and even like it. That's quite sad really. In the big scheme of things.

TO be totally honest I'd rather dump the lively Pug, dump the Seat D thing and move me, wife and kids to a patch of land in the middle of nowhere.... operate a farm smallholding, do some private contract work and live off the land year in year out.

I;m not even that interested in biodiesel really.

hdi (Paul Anderson) has had enough and more of the crap that British living brings.

Sorry HDI but itll not work. youd only be out there a couple of weeks and then a Tescos would suddenly appear over night

 

[obi_waynne]

With a McDonalds and Starbucks next door. (At least you'll be ok for food )

 

[Izo Azlion]

Damn my gullibility.


Mine'll be up closer to that in the next two weeks. Taking it out to Votex to get it Revo'd

Didnt want to create a whole new topic for it, but my Golf is being Revo'd tomorrow morning!!

They're giving me a Courtesy Vauxhall Corsa for the day! (They're keeping it in for a few hours, plus im working so its for the best)

Cant WAIT!!!