Turbo dumping to atmosphere?

[craiginuk]

After recently saying how I like to keep cars as standard as possible I have to admit I miss the whoosh and dump sound my turbo used to make with the induction kit fitted [] Is there a way to still get the dump to atmosphere sound with the std air filter setup?
I have a bailey dump/bypass valve fitted.

Pics below showing setup with the induction kit and now with std airfilter fitted. Is there any way to get the dump noise back?

 

[ChasR]

I say refit the air filter . Problem solved.

 

[Paul 290T]

Isn't the sound you are referring to caused by a dump valve being fitted instead of the standard Bosch recirc valve? When you lift off the throttle the dump valve opens and you hear the compressed air between your turbo and the inter cooler whooshing out to atmosphere.

Is your Bailey valve the same principle of operation as the standard Bosch valve, i.e. instead of dumping to atmosphere it connects the turbo's compressor outlet to its inlet? If this is the type of valve you have, then you need to replace it with a dump to atmosphere type instead.

 

[craiginuk]

I think my Bailey valve is the same principle as the std Bosch valve but used to sound different with the cone air filter. Can I dump straight to atmosphere with a different valve without causing metering problems?

 

[TTM]

You can, but the engine will run a tad richer on throttle lift-offs as the extra air that is normally recirculated is factored in the programming.
Will it harm over the long run? Not if you use good quality chips, I think.

 

[Indi9xx]

Boys and their toys

You can fit an atmospheric dump valve and get a funny/funky/cool (delete as applicable) noises when you lift off the throttle when boost is in progress.

If you partially lift off, when boost is present, but enough of a lift to open the dump valve and there is positive boost being created by the turbo, the engine will be a little richer and you may get funny/funky/cool flames from the exhaust tips if the exhaust system is hot, you might also get a little loss of refinement from the running characteristics of the engine, such as a less than ideal momentary alteration to the engine braking during the opening period.

However if you completely lift off, while boost is present, the injectors will be shut off during the over run, resulting no change to running characteristics or engine braking, still a funny/funky/cool noise, but no funny/funky/cool flames from the exhaust.

Unless of course you tell your chip supplier that you want funny/funky/cool flames from the exhaust on the over run during partial and full lift off, which is possible with or without a atmospheric venting dump valve.



In short, you might get pops and flames from the exhaust, but it will not damage your engine.... Unless you absolutely drove everwhere constantly trying to provoke it to do this, which will probably damage the engine eventually with or without an atmospheric dump valve....

There also might be some consideration to post lift spool up when you're back on the throttle compared to a recirculating valve, but it is likely to be minor.

 

[craiginuk]

Ah ok thanks for the replies. Maybe I should leave it as it is

 

[GlennS]

Craig, I vote for flames from the exhaust. Make it happen! It's a gloriously puerile thing.

 

[Eldavo]

When you lift off the throttle the car shuts off the fuel completely so as Jon says you'd need to keep a bit of throttle on.

My factory airbox is in need of repair (I'm going to try the plastic repair stuff Ken mentioned) and I already have a cone filter adaptor from my old car so I've ordered a large cone filter for the meantime. The adaptor needs drilling out to match the turbo bolt spacing but apart from that it's all good. I've seen dual port blow off valves on eBay for about £45 that let you change from fully recirculating to fully atmospheric or anywhere in between. I might get one and have a play about and see whether I can get flames with my new exhaust

 

[944 man]

With very, very few exceptions, there is no valid reason for fitting an atmospheric bypass valve. I wonder whether people who do this understand what it does and why it does it, and what happens when they mess about with it.

 

[CarreraRSR]

I want, no, I need boost chatter, pops, bangs and flames. []

http://youtu.be/lmb_HtUILHA

Non silenced Haywood & Scott rear exhaust section ready to be installed. More fuel needed to be burned on overrun and gear changes!! But do I block the recirculating valve to instigate the chatter through the turbo blades!!?

 

[Eldavo]

ORIGINAL: 944 man

With very, very few exceptions, there is no valid reason for fitting an atmospheric bypass valve. I wonder whether people who do this understand what it does and why it does it, and what happens when they mess about with it.

Go on then?

 

[924nutter]

if you want a cool noise drive the A3 tunnel create space and hit the rev limiter in 2nd. May not work on std exh but anyone who new K4 AFL will remember the big stainless oval outlet. Now that's puerile, and soooo loud

 

[Eldavo]

Wow Craig - I get it now!!!

Drove tonight with the new air filter setup and I get a lovely little noise when I lift off from on boost. As the air filter is less restrictive it lets some of the intake air out when it's being recirculated.

Get your cone back on - it's far from the chavvy noise of a VTA dump valve but a lovely little addition

 

[Patch234]

To get proper noise you need the following ingredients....mix with a little benzine..

Supercharger and turbo...

Lancia Delta S4

 

[George Elliott]

I agree with 944 man, and Group B would be one of my exceptions.

For a road car, its tiresome imo, a competition car, its OK, the helmet dulls out some noise, the transmission sounds like a jet engine, near solid bushings everywhere, no sound deadening, gravel bouncing off the underside, its probably drowned out in the background noise. Any way the Group B cars were a golden era of development, sadly finally terminated with Herni and Sergio's accident

But if you are a student at the local tech college, its a must have accessory on your Bora TDi, 306 turbo diesel, [8|][8|][8|]

George
944t

 

[ChasR]

ORIGINAL: 944 man

With very, very few exceptions, there is no valid reason for fitting an atmospheric bypass valve. I wonder whether people who do this understand what it does and why it does it, and what happens when they mess about with it.

I would like to think that I understand why BOVs are in place on cars, with the above making sense as to the changes that can occur and as to why an EML can come on in modern cars.

However, do you care to elaborate on when there are exceptions to fitting an atmospheric bypass valve? . A number of people I know hate fitting dump valves full stop even on tuned cars but that is another can of worms altogether.

 

[Eldavo]

I want to know too - genuinely interested!

 

[craiginuk]

Yep I do miss the sound might put the cone back on for a bit..

 

[craiginuk]

Just having a look at the bits I took off. The bracket in top pic was a bit of a Heath Robinson affair and the small pancake shape breather in the top pic I can't seem to find. Anyone know where I can get mounting brackets and a small breather that will fit? I think the existing breather pipe goes straight to stock airfilter so not 100% sure what size I need?