hey all, can anyone tell me how does that thing work that makes this pssss sound in cars with turbos like subaru impreza wrx?
sorry for lack of vocabulary but im new.
i heard there are things that just make noise and have nothing to do with hp's. How do these work??
Does it like go off when you push clutch???
i have no idea on the topic and im curious.
that psss thing would be nice in fiero, sad thing, mine is auto.....
thanks, dominik

I think what your asking about is a BOV aka Blow Off Valve. None the less, read this site http://auto.howstuffworks.com/turbo.htm

thanks !! that's what i was thinking about.

quote Originally posted by dozol: hey all, can anyone tell me how does that thing work that makes this pssss sound in cars with turbos like subaru impreza wrx? sorry for lack of vocabulary but im new. i heard there are things that just make noise and have nothing to do with hp's. How do these work?? Does it like go off when you push clutch??? i have no idea on the topic and im curious. that psss thing would be nice in fiero, sad thing, mine is auto..... thanks, dominik

The BOV or in some cases the compressor bypass, vents compressed air between the compressor wheel and the throttle blade. If you are at boost and suddenly let your foot off the gas (closing the throttle blade) compressed air is trapped between the compressor wheel and throttle blade and can cause damage to the VERY fragile compressor wheel.

The BOV vents this compressed air to atmosphere (hissing), a compressor bypass vents back to air intake and helps the turbo (compressor wheel) spool up faster, for example between shifts.

A BOV will "hiss" weather it is an auto or manual, assuming you eventually let off the gas ..........Paul

I had a WRX and now I have a Legacy GT. I have yet to hear the BOV make any noise from either car. The factory ones are quiet. All the ones That you can hear have aftermarket BOVs which are noisy.

yea, but you have to have turbo to have one, right?
can you just buy something that makes this noise and has nothing to do with power?
would that work with auto tranny?
just curious, thanks, dominik

Yes, thay DO sell things that make the "Pssst" sound. I think one that even shoots out a little spray of smoke-stuff.
They also have little things that make the supercharger sound, i believe...
Might as well weld one of these on and call it a day:

[This message has been edited by FieroRumor (edited 05-23-2005).]

quote Originally posted by dozol: yea, but you have to have turbo to have one, right? can you just buy something that makes this noise and has nothing to do with power? would that work with auto tranny? just curious, thanks, dominik

not sure why you would want a phony BOV, but you could always hook up a little compressor and hit the on trigger between shifts

quote Originally posted by avengador1: I had a WRX and now I have a Legacy GT. I have yet to hear the BOV make any noise from either car. The factory ones are quiet. All the ones That you can hear have aftermarket BOVs which are noisy.

That's because the factory cars use what I call the Compressor Bypass, a sealed system. The CB connects to the compressor outlet tube, and then to the compressor intake. It does the same thing as a BOV except that rather than venting to atmosphere, it routes the compressed air back to the compressor intake. I installed a Miller-Woods turbo on my 2.8 in 1990 and they used the compressor bypass rather than the BOV. As I have said the CB keeps the compressor "spooled", the BOV just vents to atmosphere, thus the "hissing" noise. If you disconnet the CB tube to the compressor inlet it will "hiss" also.

You must have either the BOV or the CB, or you will damage the compressor wheel. The CB makes more sense, the BOV makes more noise. Take your pick.........Paul

I remember seeing a gadget that made the blow off sound, there also was one that made a fake turbo sound. You might find it on the forum as it was here that I saw it.

A functioning BOV also helps to keep you from shooting the headgaskets out the side of your block, ask FieroX about that one.

JazzMan

APC probably sells them...

[This message has been edited by 2birds (edited 05-23-2005).]