Blow Off Valve for 2.4

[JabawokJayUK]

Calling all diesel experts...

I would like to add a blow off valve to my 2.4, and wanted to know if this was possible and an idea of which valve I should be looking at.

I dont want this to turn into a debate about the merits of them, and yes, I know it will not effect performance etc, and yes, I accept the purists will cringe at the thought of this technology being introduced to an Alfa, but I just want to add one for ****s n giggles.

So that said, any ideas which one, where I might go next to figure out next steps etc?

Thanks!

[AlexT]

..you realise that the combination of a blow off valve + diesel engine will make your car sound like a bus, right?

[JabawokJayUK]

It already dumps the air back through the turbo and with no DPF its a very loud woosh, that will be exaggerated when the decat and straight through exhaust get fitted. This upgrade will stop the pressure being pushed back through into the turbo and out the exhaust, so will change the sound and reduce turbo back pressure (i think).

either way, it already sounds like a tractor, so in for a penny.....

[wynne71]

Do these cars have a re circulatory dump valve or an atmospheric one?
If it is the former, an atmospheric valve will play merry hell with the performance and turbo lag.

[AlexT]

would be so kind to talk me through the way this blow off valve exactly works then? I'm not sure I understand how air is dumped back into the turbo. I'm not being sarcastic, I mean it!

[wynne71]

From my Saab petrol turbo days there were two types (probably go this wrong, but from memory....).

Atmospheric: the ones that you usually hear strapped to Scoobies etc. As the pressure builds in the turbo, some is used to spool the turbo under load, what isn't required is "dumped" back into the air, under the bonnet. Hence the massive psssffftttt noise you sometimes hear when the pimped turbo cars go by.

Re circulatory: the boost built up and then not used (as above) is then re fed into the system, prepping the boost for the next stage. A more efficient system but prone to worn valves. In the Aero I had a Forge aluminium one was used to swap for a failed Saab plastic one, held the pressure for longer creating more boost over a shorter time.

Hope I am at least somewhere near correct........

[adamcot]

Those are correct Wynne, but a diesel has no throttle body as such, and therefore a dump valve won't work

The noise you can here is merely the turbo spooling and slowing down, no worse than that. You won't hear that on a turbo petrol as most have re-circ valves which masks the noise. Nothing to worry about

[Daniel350]

Also most Turbos nowadays (Including Alfa petrol and Diesel) are Variable Vane Turbos. They don't have Dump valves at all as they aren't needed. The vanes are Variable therefore at low RPM they allow a smaller amount of pressure to be built up quicker helping alleviate the old Turbo lag a bit and then when the Pressure reaches a pre-determined pressure the ECU backs of the vanes therefore reducing the boost,

Instead of the old days where fixed vanes where the manufacturer decided how big the turbo was therefore how much pressure it could create. (Larger turbos created more power but also more lag as proved when a Evo with 420Bhp had a drag race with some small family car on Top Gear starting at 30Mph in Top Gear and the Evo lost). When the predetermined pressure was reached the turbo carried out as before but the Dump valve, dumped the excess pressure.

[JabawokJayUK]

All about blow off valves:

+ YouTube Video

Blow off valve attached to various Diesels:

+ YouTube Video

+ YouTube Video

+ YouTube Video

Now, if it does effect performance, its NOT going to happen, but if it does what I think it does, then it cant hurt.

[David C]

Originally Posted by Daniel350

Also most Turbos nowadays (Including Alfa petrol and Diesel) are Variable Vane Turbos. They don't have Dump valves at all as they aren't needed. The vanes are Variable therefore at low RPM they allow a smaller amount of pressure to be built up quicker helping alleviate the old Turbo lag a bit and then when the Pressure reaches a pre-determined pressure the ECU backs of the vanes therefore reducing the boost,

Instead of the old days where fixed vanes where the manufacturer decided how big the turbo was therefore how much pressure it could create. (Larger turbos created more power but also more lag as proved when a Evo with 420Bhp had a drag race with some small family car on Top Gear starting at 30Mph in Top Gear and the Evo lost). When the predetermined pressure was reached the turbo carried out as before but the Dump valve, dumped the excess pressure.

You are talking about wastegates, not dump-valves.

[Alfadisiac]

The second video:
The dump valve was dumping pressure whilst the bloke was still revving! Now I'm now expert, but a dump valve shouldn't dump until the foot is taken off the accelerator!

[JabawokJayUK]

From what I have read there are lots of different types of valves that can be tuned as to when they open. Perhaps that one was just not set up right.

[adamcot]

I'm not saying you can't fit one, but why would you

There is absolutely no performance or reliability gain from running one on a diesel engine

If you just want the sound, maybe go and buy an Impreza, as you have the wrong car

[JabawokJayUK]

Originally Posted by adamcot

I'm not saying you can't fit one, but why would you

There is absolutely no performance or reliability gain from running one on a diesel engine

If you just want the sound, maybe go and buy an Impreza, as you have the wrong car

Thanks Adam, quality comment there, as I said at the start, its not a debate, and I have my reasons. The beauty of life is choice, and this is mine, I am asking for advice if people have it, not opinion.

As for the scooby comment, you know, the one thing I hate about the alfaforum is the purist comments. At least on scoobynet people are open to innovation and new ideas.

PS putting a thumbs doesnt take the edge off your comment, does it ?

[AlexT]

man, seriously, what do you expect? I don't mean to offend you, but it sounds to me like a really unnecessary/chavvy idea that doesn't really marry well with the class and style of an Alfa 159, cos all it does is adding a very annoying WHOOOOSH sound to your car.

Scooby drivers are renown for the open mind attitude, all in all they drive minging looking cars

[JabawokJayUK]

Strangely I expect people to open to new ideas and accepting of other peoples tastes, but clearly I am in the wrong place for that.

I keep forgetting we are all driving the most amazing auto-mobiles ever created. built to such a super high specification with no compromises, that should only ever be polished, adored and occasionally driven, very sedately, in-case we get a stone chip or a splash of water on them. Oh wait, I remember, Alfa is owned by Fiat, so that's all crap then. Incidentally, there is a decent amount of info on this subject for the JTDM engines on the fiat forum so perhaps I should ask the question there instead.

My 159 is a work in progress that Alfa started, and I will finish with as many fairy lights, chavy noises and engine bending performance tweaks as I deem appropriate for me, with or without the approval of my peers. I am always amazed by the number of Alfatrolls on here, its truly astounding.

[Joomoo]

will it pass mot?

[stefanocirillo]

A neighbour of mine has a alfa GT 1.9 Jtd with a dump valve. I will try and find out how he did it for you...

[AlexT]

it's a matter of personal opinions, what you call alfatrolls probably would call you alfachav; funny how you diss the folks that like to take care of their car but get your knickers in a twist if someone says something about your project.

Each to their own really, but expressing such "innovative ideas" in a public forum and not expecting some raised eyebrows or sarcastic comments is naive to say the least.

[JabawokJayUK]

yes, all current mods will pass an MOT, as proven by all the other forum members that have made them and had there cars MOT'd recently. I don't plan on making my car unsuitable for road use just yet, but I reserve the right to turn it into a track toy at some stage.

[JabawokJayUK]

Originally Posted by JabawokJayUK

Calling all diesel experts...

I would like to add a blow off valve to my 2.4, and wanted to know if this was possible and an idea of which valve I should be looking at.

I dont want this to turn into a debate about the merits of them, and yes, I know it will not effect performance etc, and yes, I accept the purists will cringe at the thought of this technology being introduced to an Alfa, but I just want to add one for ****s n giggles.

So that said, any ideas which one, where I might go next to figure out next steps etc?

Thanks!

@ AlexT.

I only dis those incapable of reading the first post.

[JabawokJayUK]

Originally Posted by stefanocirillo

A neighbour of mine has a alfa GT 1.9 Jtd with a dump valve. I will try and find out how he did it for you...

Thanks Stephan, you just restored my faith in the forum, any pointers you can give on type / model to aid my research are appreciated.

[coxy1]

Originally Posted by JabawokJayUK

Strangely I expect people to open to new ideas and accepting of other peoples tastes, but clearly I am in the wrong place for that.

I keep forgetting we are all driving the most amazing auto-mobiles ever created. built to such a super high specification with no compromises, that should only ever be polished, adored and occasionally driven, very sedately, in-case we get a stone chip or a splash of water on them. Oh wait, I remember, Alfa is owned by Fiat, so that's all crap then. Incidentally, there is a decent amount of info on this subject for the JTDM engines on the fiat forum so perhaps I should ask the question there instead.

My 159 is a work in progress that Alfa started, and I will finish with as many fairy lights, chavy noises and engine bending performance tweaks as I deem appropriate for me, with or without the approval of my peers. I am always amazed by the number of Alfatrolls on here, its truly astounding.

Good for you, you paid for it paint it pink with yellow spots if you want.

Not to hard to reto fit your dump valve, inset a sleave in the intercooler to manifold pipe with a take off for your dump valve. You would need to by an adjustable pressure dump valve so that you could adjust the blow off pressure to suit. The hardest part would be finding a pressure take off to operate it, poss tee into the boost guage pipe ?. As to how well it would work, noise wise, with the varible vain turbos I dont know as it may pressure down very quickly. Not broken one yet so not has the chance to play. All the bits you need should be on here

Alloy T Piece Joiner - Polished Alloy T Connector - Choose Your Size

Have fun

[JabawokJayUK]

Coxy, you rock.

Cheers for that!

[Joomoo]

why not spend the money on bigger turbo with no whoooch ,not big fan of whoooch
by the way, last month my turbo was doining wheeee wheee.... had to rebuild it