Souhlasim se vsim co rek HomoFaber, krome:
Pop off a Bov je to same. Neni a bohuzel opakuje stejnou chybu jako jini, staci si procist diskuze profesionalu, co stavi zavodni auta, napr. zde:
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There is a huge Difference in a pop off valve and a blow off valve.
A BLOW-OFF Valve is mounted on the intake before the throttle body has a spring in it which holds the pressure in the intake pipes until the throttle is close, when the throttle is close the engine goes into a vacuum which opens the valve and releases the pressure. If it did not release the pressure in the pipes, as soon as the throttle is close all the dense air(boost) from the turbo will smack a wall(the throttle plate) and that will shorten the life of the turbo drastically. There are 3 different types of BLOW-OFF Valves, you have, Vend(then make the swoosh sound every time you change gears, obviously because its venting off the excess pressure) Not Very good Unless the car is running a MAP sensor(It is releasing air that has been measured and accounted for by the cars computer), Then you have recirculating its quieter but you slightly hear it(with more boost) instead of wasting the air it sends it back to the intake side of the turbo(allows faster spool up of the turbo). Then you also have the combination BLOW-OFF Valve, it recirculates most of the air but vents just enough to have the Cool Swoosh sound.
A POP-OFF Valve is is mounted after the throttle body and used to prevent over boosting(and to regulate the manifold pressures in cart cars,
More pressure=More power). It also has a spring in it which is set to a predetermined pressure and as soon as it hits that pressure it opens and releases the excess. Most after-market BLOW-OFF Valves come with a set of spring shims(the more shims, the more pressure you can run before it leaks, some even come with a set of spring, those are the better ones to get). These are not used much outside of cart racing and drag racing but are used on some cars like the 80's 300zx, mostly because it did not have a BLOW-OFF Valve, and from what I recall the pop off valves are a cheap way to regulate pressure and Nissan did it and a few other thing to bring the price of the 300's down because everything else was ridiculously expensive(they had digital gauge clusters and digital climate control)(Its a small can on the front left"if looking at it from the front" of the intake plenum if you want to see one).
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Dokonce nekde mam i fotky POP off ventilu, akorat je musim najit, je konstrukcne odlisny (a jednodussi nez BOV), nema podtlakovou hadicku rizeni, ma jen pruzinu, kde se nastavuje tlak kalibrovanyma podlozkama. BOV jsou samozrejme vsude napr:
http://www.bidrin.cz No a ta vlna to turbo samozrejme brzdi, netvrdim, ze jej zastavi na nulu z 90.000 nebo i 180.000ot/min, ale rozhodne ho protitlak a vibrace v sani nepovzbudi...
Me po instalaci poradneho velkoobjemoveho BOV od Perrin Performance opravdu auto ziveji reaguje, a to jsem ho zapojil 50% zpet do sani a 50% do atmosfery, protoze kdyz si odfoukne jen do atmosfery, MAF uz ten vzduch ztraceny vzduch ma nacteny (prosel pres senzor) a tudiz dava prilis bohatou smes. Ta sice motor neposkodi (jako chuda), ale taky mu moc nepomuze k vykonu, ale abych mel moje psiiit, tak jsem udelal tenhle kompromis.