Comment installer un Blow of valve sur 1.8T VW

[tom__1979@]

Comment installer un Blow of valve sur une VW Jetta 1.8T 2003???

j'ai regardé sur vwvortex et j ai rien trouvé!!!

Par contre j'ai trouvé comment désactiver les lumieres de jours...

Merci

Marc

[templar]

Salut Marc,

En tapant "how to install BOV" dans la fonction "Recherche" des forums vwvortex j'ai eu plusieurs réponses. En regardant rapidement, je n'ai pas trouvé les étapes détaillées de l'installation, mais ça ne semble pas trop compliqué...sauf pour défaire les "clamps" d"origine. Plusieurs semblent ne pas recommander de faire cette modif cependant... Sinon, souvent les manufacturiers (ou vendeurs) des pièces peuvent te fournir le mode d'installation. As-tu visité des sites comme ceux de Neuspeed, New Dimensions, Autotech, Eurosport, APR, etc?

Je crois qu'au début, la pièce d"origine faisait souvent défaut, c'est pourquoi les gens la changeait pour une "plus performante". Le problème semble réglé chez VW. De plus, il semblerait que la plupart des BOV feraient allumer la lumière "check engine" selon ce que j'ai lu...

Un meilleur "upgrade" serait une nouvelle puce électronique, genre APR. C'est plus dispendieux mais ça augmente plus les performances. Par contre, gare à la garantie si ton concessionnaire s'aperçoit de quelquechose!

Templar

[dunlop5120]

C'est quoi un Blow-off valve....j'imagine que c'est pour le turbo, mais comment ça fonctionne et c'est quoi...si quelqu'un a un lien j'aimerais bien voir ça....thanks

[100limites]

Je suis pas un expert en turbocompression mais voici tout de même ma synthèse : :roll: SVP corrigé moi si j'ai tord.

À fur et à mesure que le moteur monte en révolution, le turbocompresseur compresse l'air se dirigeant vers l'intake manifold. Mais quand il vient le temps de changer de vitesse, il faut alors que le RPM du moteur redescende le plus vite possible, ce qui n'est pas facile si l'air demeure comprimé dans l'entrée d'air et le manifold. La blow off valve permet donc d'évacuer très rapidement cette pression pour permettre au RPM du moteur de redescendre plus rapidement. C'est alors qu'on entend le magnifique ''pssshiiitttt'' (j'adore ce son 8))

http://www.greddy.com/products/images/blowoffvalves.gif

Voici la description du site www.greddy.com sur les blow off valve :

Turbo lag is the enemy of any turbocharged vehicle. Our Blow Off Valves are easily adjustable to prevent both premature boost leakage and compressor surge. Each is made of durable cast and billet aluminum frame, and the valve to diapharm ratio provide preformance that cheep piston types can not offer. The spring stiffness adjustment screw and the two different sizes give the GReddy user the option to match vehicles with mild upgrades to heavily tuned engines. Also available in easy to install kit form for most Japanese turbocharged vehicles.

[Brad]

Bonne expliquation. Et oui le son qui produit la BOV est assez thrillant, ça donne un bon sentiment de puissance mécanique, toujours est-il que le travail doit être bien fait.

[tom__1979@]

J'ai trouvé sur VWVortex que le BOV fait alumer la lumiere du check engine. Alors qu'il est mieux d'installer une diverter valve inversé, qui donne le meme pishhhhhhhhh que je recherche.

Marc

[templar]

Salut Marc,

Autrement dit, tu recherches plus le "pschitt" que l'augmentation de performance...!?

Je sais que les BOV (ou diverter valve) de marque "Forge" ont (ont eu du moins) la cote pour les proprios de VW. Ils ont peut-être ce que tu recherches.

Sinon, peut-être que des recherches d'info à des endroits comme RMR Autosport à Montréal, TRAC Racing à Laval ou même Import-Expert à Québec (tu es de Québec je crois) pourront te fournir de l'info. Il en existe plusieurs autres également.

Templar

[dunlop5120]

Et les turbos de série de VW ne viennent pas avec ou il n'est pas bon de cie..

[guy_geo]

Le problème, en fait c pas un problème, mais avec les BOV d'OEM, cc'est qu'elle renvoie l'air dans l'intake, elles osnt internes à 100%..

Imagine la tite madame ou bine le gars qui n'y connaît en mécanique qui fait l'essai et entend ce bruit pour la première fois..

Ce n'est pas tout le monde qui est maniaque comme nous..

Ma WRX à un GFB (GoFastBits)
http://www.gofastbits.com.au/

comme celle-ci.

http://www.gofastbits.com.au/2002_hybrid.jpg


J'aime bien surprendre les conducteurs l'été en changeant de vitesse lorsqu'ils ont la vitre baissée... et synchroniser le psiiiht juste quand le moteur est vis-à-vis la fenêtre.... Ça surprend toujours... :P

Quand au fait que cela produit plus de HP, je suis TRÈS sceptique..

Mais il ne faut pas oublier aussi de la nettoyer régulièrement, la mienn est nettoyés tous les 4-5000km, soit en même temps que mes changements d'huile..
Il y aura comme un dépot graisseux et noir à l'intérieur de la valve, ce qui diminue son efficacité.

POurt plus de détails:

They're engineered to produce peak performance under ALL conditions. A blow-off valve comes into play when the throttle is closed suddenly under boost conditions. A poor quality component actually slows acceleration and can cause "compression stall" … causing you to stall at the lights.

But that's the least of your problems. Imagine your turbocharger spinning at 80,000rpm pumping a truckload of air through your inlet pipes at nearly 90 metres per second … then you suddenly close the throttle. The "reverse thrust" forces produced are so huge, you can end up with a damaged turbocharger!

GO FAST BITS Hybrid blow-off valves overcome the problem by venting most of the non-required intake pressure into the atmosphere, while a small portion is vented back to the turbo and airflow meter-enough to stop problems such as excessive fuel use, backfiring and engine shudder at half acceleration (experienced with purely venting-to-atmosphere valves).

The majority of factory-installed blow-off valves vent ALL the air back into the inlet pipes, usually after the air flow meter. That also means the pressurised air is returned to the turbocharger in a HOT condition … and hot air produces poor power!

POur le reste, c bine long, mais ça explique pas mal tout...

And How Does a GFB Valve Do All Of This?

1-2) Most turbo cars have some form of factory blow off valve (sometimes referred to as bypass or anti-surge valves), most of which dump the excess turbo pressure back into the inlet to reduce or eliminate the associated noise. It is common for factory valves to open at very slight vacuum signals, meaning that whenever your manifold pressure is not experiencing boost, the valve is wide open and is recirculating a significant amount of air from the turbo's outlet to it's inlet. This means that for about 95% of the time that you are driving your car, the turbo is trying to generate boost but can't until the valve shuts. In this condition you might as well take the turbo off the car!

If a slight throttle increase is made (say to maintain speed on a freeway up a small rise) and the manifold pressure makes the transition from vacuum to boost, the valve closes. So the rather significant amount of air that has been pumped around in circles by the turbo is now pressurised and directed at the engine. The end result is an annoying surge that makes freeway speeds difficult to maintain.

A GFB Blow Off Valve uses the correct spring pressure to keep the valve closed until it is needed, so that the turbo's energy is not going to waste at light throttle applications. End result? You now use less throttle to drive the car around for the 95% of the time that is not spent on boost, meaning better fuel economy.

3) A factory blow off valve is only designed to cope with factory levels of power, and tests performed on a variety of them show that they leak significantly at boost pressures as low as 3psi! Why waste that boost? It is also important to realise that a small boost increase of 2-3psi will quite dramatically increase the speed of the turbo and the airflow passing through it, and it is almost certain that a factory valve will not be able to vent the required volume quickly enough to prevent damage to the turbo.

Quite often a factory valve will be undersized, and will compensate by staying open for ridiculous periods of time. GFB Blow-Off Valves utilize an acetal seal in the closed position to ensure NO LEAKS under boosted up conditions, and the generous porting will easily vent larger quantities of air more rapidly. The spring pressure is also adjustable to enable the valve to be tuned to the boost level being run.

4) If you want people to know that you are driving a turbocharged car, you need the WHOOOSH noise between gear changes! GFB Blow-Off Valves come in a range of venting arrangements to suit your needs. Choose from the silent operation of the plumb back model, to the ear-shattering twin trumpet Bovus Maximus. Or for the best of both worlds in cars with airflow meters the hybrid allows some air to be plumbed back to keep the ECU happy, while still gracing pedestrians with that distinctive roar!

How a Blow-Off Valve Works:

Most Blow-Off Valves utilise a piston or stem valve, using a spring to return it to the closed position. The inlet port of the BOV is plumbed into the inlet tract of the engine somewhere between the turbo outlet and the throttle body, and is usually arranged so that the boost pressure pushes the piston against the spring. The other side of the piston is a sealed chamber that is connected to the inlet manifold after the throttle body via a vacuum hose.

When the throttle is open and the turbo is making boost, there are relatively equal pressures on both sides of the piston, allowing the spring to keep it tightly shut. When you close the throttle rapidly, the increase in pressure on the turbo side of the piston and resulting vacuum on the manifold side create a large differential, which snaps the valve open and allows the turbo to freewheel.

What Does a Blow-Off Valve Do (apart from the noise!)?:

The vast majority of turbo owners fit aftermarket blow off valves simply for the signature noise that they make between gearshifts. While that may be reason enough to fit one, they do actually serve a more important purpose than that. A common misconception is that if a turbocharged car doesn't make a "whoosh" noise, it doesn't have a blow-off valve. Almost every modern turbo car will have some form of blow-off valve, except that the vented air is returned to the inlet tract before the turbo to muffle the sound.

A good analogy for what happens in a turbo system when you close the throttle is water hammer in household pipes when you turn the tap off too quickly. The same thing happens when your turbo is spinning at about 100 000 RPM, pumping pressurised air into the engine. When the throttle butterfly snaps shut for a gearshift, that air (which can be travelling at up to 90 metres per second) has nowhere to go except back the way it came and out through the turbo. This is bad for a number of reasons. First, slowing the turbo from maximum RPM to practically zero in less than a second is obviously going to place a lot of strain on the turbo. Secondly, since the turbo has stalled, the lag when you open the throttle again is increased.

The BOV is designed to release excess pressure under these conditions to allow the turbo to freewheel, which both prevents damage and reduces lag. The noise is achieved simply by venting the air externally.
8)

[louis4]

Salut a tous je voudrais savoir comment ont fait pour que mon turbo fesse le fameux pshiiit que vous parlez quoi quil est déja chippé;je pense avoir a peu pres 200 hp quoi que je suis un peu plus rapide que la nouvelle GLI anyway si ya moyen de faire ciler davantage le turbo ca serait magnifique merci

LOUIS

[dunlop5120]

Il te faut une BOV externe et non interne...elle expulsera alors l'air vers l'ext. au lieu que dedans l'intake. Mais t'auras aucun gain, même qu'une BOV trop ouverte ou trop fermé peut endommagé ton turbo. Ordinairement le best c'est d'intaller un boost/vac gauge pour lire le vac et setter comme la BOV d'origine.