is a blow off valve a really good idea? does it make yu lose boost? does it make yu lose horsepower and is it a good idea for a car making lots of power?

You don't loose boost or horsepower. When a turbocharged engine spools up, it pressurizes the intake system, which forces more air into the combustion chamber. When you take your foot off the accelerator, that pressure stops instantly and the excess pressure must go somewhere. If not for the BOV, the pressure would reverse direction and return back up the intake system, creating undue stress on the turbocharger's components. This pressure return would also reduce the velocity of the compressor wheel, meaning it will take much longer to spool up again when the throttle is opened.

will it open up when making boost, spooling up? or only when yu let go of the accelerator? and is it good for high performing engines as ive since many fast cars not have them

you will not loose HP or boost, but will loose a lot of the most impotent thing. Respect. ---------- Post added 08-01-12 at 20:06 ---------- Its opend by vacuum made by closing your Throttle, closing your throttle makes big vacuum one side and big pressure the other, So it uses one force to release the other.

is it better to have it or not have it? im only asking as i bought a intercooler with a bov plumbed into it and im going to be making quite reasonable power and i want to know if its better to have it or just block it up,

If the engine runs an air flow meter it is a good idea to use a plumb-back blow off valve, set-up correctly. Running no blow off valve or a blow off valve that vents to atmosphere will cause excessive richness when the throttle is closed (only with AFM's). Running a blow off valve will also reduce stress on the turbocharger but, it isn't necessary.

if you want too run one just make sure its set high, so you have to be say 25+ PSI before it opens and not huffing your way around town all the time like a wanker. if i was running 25+ PSI i would have a bov set high, but only running around 20PSI i didnt bother and love the flutter.

Thanks guys for this info im not running a BOV either and was nor sure if i really need one

what would you guys recommend, use one or not?

use it

ok i have a adjustabe one, it vents into the atmosphere. i will probly just put it all the way to hard so it rarely comes on, im going to be running around 20 psi,

this has been discussed at great length prev, do a search and you'll find find the prev discussion