Blow-Off Valve !
Publié : ven. mars 01, 2002 10:15 pm
Bon ou mauvais achat ?
pour : ?
contre: ?
Merci !
pour : ?
contre: ?
Merci !
Sauf que le bruit c'est cool! ptchiiiii!!!
Page 1 sur 2
Publié : ven. mars 01, 2002 10:32 pm
t'en a une deja sur ton WRX seulement qu'elle n'est pas bruyante.
Sauf que le bruit c'est cool! ptchiiiii!!!
Sauf que le bruit c'est cool! ptchiiiii!!!
Publié : sam. mars 02, 2002 8:34 am
certain on même optenu des pertes de puissance en mettant ca sur leur wrx...
je trouve que c'est complètement une perte d'argent
je trouve que c'est complètement une perte d'argent
Publié : sam. mars 02, 2002 9:55 am
Merci !
Publié : sam. mars 02, 2002 12:15 pm
Perte de puissance?!
A moins que je ne comprenne pas le principe, je vois pas comment tu peux perdre ou gagner de la puissance quand justement le BOV sert a faire sortir la pression excessive...
A moins que je ne comprenne pas le principe, je vois pas comment tu peux perdre ou gagner de la puissance quand justement le BOV sert a faire sortir la pression excessive...
Publié : sam. mars 02, 2002 1:51 pm
je connais pas trop le principe, mais y parait que quand on laisse le bov à pression atmosphérique ca donne pas le même résultat
Publié : sam. mars 02, 2002 2:06 pm
Tu me perd là Franky.....
Atmostphérique quoi??
Blowoff valve sert juste à faire sortir l'air qui s'en allait au moteur et qui frappe le throttle body, à la place de revenir au turbo et de faire ralentir le turbo (à cause du retour d'air) ben elle sort dans le hood, ou elle retourne au turbo. Tout depend du model.
Atmostphérique quoi??
Blowoff valve sert juste à faire sortir l'air qui s'en allait au moteur et qui frappe le throttle body, à la place de revenir au turbo et de faire ralentir le turbo (à cause du retour d'air) ben elle sort dans le hood, ou elle retourne au turbo. Tout depend du model.
Publié : sam. mars 02, 2002 2:16 pm
Oki, je vais essayer de comprendre ici le ce qui se passe..
Il a 2 sorte d'installation de BOV.. Une, en recirculation, lautre, il pitch lair dans latmosphere (Bov atmospherique)
En mettant la BOV atmospherique, la voiture devrait rouler + riche que ce quelle roulait avant, car, lair qui est pitcher dans latmosphere a deja ete calculer par le Mass Air Flow qui est avant.. En recirculation, lair retourne dans lintake et ca fini la..
En t k, moi sur mon auto, je roulais en mode Atmosphere, et cetais cela que tout le monde sur iclub et ailleur m'avait donner comme explication.. Egalement, certaines voiture avec un MAF, pourrait avoir un trouble de Idle avec une BOV atmosphere (cest pas toute les voitures, certaine corrige et accepte).. Moi mon RS, javais un trouble avec cela.. mais jetais habituer, et javais trouver une methode pour pas que le char stall ..
en t k, je voie pas trop trop moi non plus, comment la Bov pourrait faire pour enlever de la puissance.. a part du fait que en roulant plus riche. cela = moins de performance..
mais bon, cest juste une theorie que je viens de sortir de ma tete la
Est-ce la bonne ou pas.. ???
Il a 2 sorte d'installation de BOV.. Une, en recirculation, lautre, il pitch lair dans latmosphere (Bov atmospherique)
En mettant la BOV atmospherique, la voiture devrait rouler + riche que ce quelle roulait avant, car, lair qui est pitcher dans latmosphere a deja ete calculer par le Mass Air Flow qui est avant.. En recirculation, lair retourne dans lintake et ca fini la..
En t k, moi sur mon auto, je roulais en mode Atmosphere, et cetais cela que tout le monde sur iclub et ailleur m'avait donner comme explication.. Egalement, certaines voiture avec un MAF, pourrait avoir un trouble de Idle avec une BOV atmosphere (cest pas toute les voitures, certaine corrige et accepte).. Moi mon RS, javais un trouble avec cela.. mais jetais habituer, et javais trouver une methode pour pas que le char stall ..
en t k, je voie pas trop trop moi non plus, comment la Bov pourrait faire pour enlever de la puissance.. a part du fait que en roulant plus riche. cela = moins de performance..
mais bon, cest juste une theorie que je viens de sortir de ma tete la
Est-ce la bonne ou pas.. ???Publié : sam. mars 02, 2002 2:21 pm
Mike tu me voles les mots de la bouche
Publié : sam. mars 02, 2002 2:25 pm
Bon , voici l'interprétation que j'en ai..
De ce que j'ai compris, la BOV, c'est une safety switch pour pas que les PSi montent trop haut.
Par exemple, sur mon eclipse, la BOV de compagnie commençait à ouvrir vers 13 psi.
Je l'ai changée pour une HKS ajustable, de cette façon , je pouvais retarder un peu le leak et de cette façon, avoir plus de puissance vers la fin de la courbe de psi. Ainsi, la nouvelle BOV ouvrait vers 15-16?.
Faut faire attention pour ne pas la mettre trop tight car kaboum!!
Corrigez moi si je suis dans le champs, mais je crois que ca l'a ca place dans une série de mods , c'est pas la premi`re a faire mais pour les maniaques..
a+
Bbob
De ce que j'ai compris, la BOV, c'est une safety switch pour pas que les PSi montent trop haut.
Par exemple, sur mon eclipse, la BOV de compagnie commençait à ouvrir vers 13 psi.
Je l'ai changée pour une HKS ajustable, de cette façon , je pouvais retarder un peu le leak et de cette façon, avoir plus de puissance vers la fin de la courbe de psi. Ainsi, la nouvelle BOV ouvrait vers 15-16?.
Faut faire attention pour ne pas la mettre trop tight car kaboum!!
Corrigez moi si je suis dans le champs, mais je crois que ca l'a ca place dans une série de mods , c'est pas la premi`re a faire mais pour les maniaques..
a+
Bbob
Publié : sam. mars 02, 2002 2:32 pm
Pour moi un BOV c'est:
Psshhh Pssshhhh Pssshhh
ou encore le son de la wrx a Nichols que j'suis pas capable d'interpreter en langage ecrit
Si j'avais une WRX ca serait la premiere chose que je mettrais dessus!!
Psshhh Pssshhhh Pssshhh
ou encore le son de la wrx a Nichols que j'suis pas capable d'interpreter en langage ecrit
Si j'avais une WRX ca serait la premiere chose que je mettrais dessus!!
Publié : sam. mars 02, 2002 4:31 pm
personnelement je trouve que les wrx sont pas mal chequé par la police (etk dans mon cas) avec un bov aftermarket je crois que ce serait encore pire (mais je ne pense pas qu'il y a un rêglement fait pour les bov??)
si vous voulez quand même vous en acheter une, allez voir sur ebay il y en a plusieurs qui se vende à moitié prix (et la raison de la vente c'est souvent : le son est trop fort...)
si vous voulez quand même vous en acheter une, allez voir sur ebay il y en a plusieurs qui se vende à moitié prix (et la raison de la vente c'est souvent : le son est trop fort...)
Publié : sam. mars 02, 2002 6:23 pm
moi je suis d'accord avec franky, des gars sur le i-club avec des wrx on eu une perte de puissance avec des bov aftermarket.... Le fait que la bov athmospherique te fait rouler riche entre les shift fais boger le turbo!!! donc apres le shift 1-2 le turbo va boger pour 1 sec avant de repartir!!
en passant franky j'ai acheter ma wrx...elle va etre prete dans 3 semaine, jai deja acheter un greddy profec b boost controller et une greddy boost gauge, spring h&r, painted side skirt.... si tu est disponible tu pourrait venir avec moi voir andre pour l'exhaust, je vais y aller un mardi
en passant franky j'ai acheter ma wrx...elle va etre prete dans 3 semaine, jai deja acheter un greddy profec b boost controller et une greddy boost gauge, spring h&r, painted side skirt.... si tu est disponible tu pourrait venir avec moi voir andre pour l'exhaust, je vais y aller un mardi
Publié : dim. mars 03, 2002 1:01 am
Bob rs. Je crois que tu parle de waste gate et non de BOV. non??? 
Publié : lun. mars 04, 2002 9:54 am
C'est long mais c'Est ce que ca fait !!!
En passant on en vend des bov !!!
Julien Pilon
Lachute Subaru
GFB Blow-Off Valves are the only valves on the market to boast these unique features:
· The brass piston features a taper that in the closed position seats against an acetal seal that means it WILL NOT LEAK under boost. The bore also features a quad-ring seal to maintain the integrity of the vacuum signal that opens the valve for quick reaction. All the other valves in this class rely on the diameter of the piston for sealing, and after a while the wear associated with the operation of the valve will increase the amount of air that leaks out through the bore.
· During operation the piston of a blow-off valve shuts rapidly onto the stop, where the acetal seal in the GFB valve cushions the impact. Other valves do not have this feature, and eventually the soft brass piston can become severely damaged, causing jamming problems due to brass flakes.
· Manufacture of GFB products is carried out on the latest multi-axis CNC machines under the international quality standard ISO 9000.
· GFB Blow-Off Valves are physically smaller whilst retaining the same high airflow characteristics of other valves, however the smaller size means they are more suited to modern engine bays.
· GFB Blow-Off Valves are versatile. They can be mounted in two different ways, either as a push fit inside the factory rubber hoses with a variety of different sized fittings to suit all turbo vehicles, or they can be mounted onto a 1 inch O.D. steel or alloy pipe.
· The piston uses less material for low inertia, which translates to a faster response time.
Why Fit a GFB High Performance Blow-Off Valve?
Four reasons:
1) Driveability
2) Fuel efficiency
3) Boosting up applications (factory valves can leak like a sieve!)
4) The noise!
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.
En passant on en vend des bov !!!
Julien Pilon
Lachute Subaru
GFB Blow-Off Valves are the only valves on the market to boast these unique features:
· The brass piston features a taper that in the closed position seats against an acetal seal that means it WILL NOT LEAK under boost. The bore also features a quad-ring seal to maintain the integrity of the vacuum signal that opens the valve for quick reaction. All the other valves in this class rely on the diameter of the piston for sealing, and after a while the wear associated with the operation of the valve will increase the amount of air that leaks out through the bore.
· During operation the piston of a blow-off valve shuts rapidly onto the stop, where the acetal seal in the GFB valve cushions the impact. Other valves do not have this feature, and eventually the soft brass piston can become severely damaged, causing jamming problems due to brass flakes.
· Manufacture of GFB products is carried out on the latest multi-axis CNC machines under the international quality standard ISO 9000.
· GFB Blow-Off Valves are physically smaller whilst retaining the same high airflow characteristics of other valves, however the smaller size means they are more suited to modern engine bays.
· GFB Blow-Off Valves are versatile. They can be mounted in two different ways, either as a push fit inside the factory rubber hoses with a variety of different sized fittings to suit all turbo vehicles, or they can be mounted onto a 1 inch O.D. steel or alloy pipe.
· The piston uses less material for low inertia, which translates to a faster response time.
Why Fit a GFB High Performance Blow-Off Valve?
Four reasons:
1) Driveability
2) Fuel efficiency
3) Boosting up applications (factory valves can leak like a sieve!)
4) The noise!
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.