hi u guys doing? new to the forum, glad to be here, well heres my question, maybe be a dumb question but, i have a swapped T-II 91 in a N/A 90 Shell anyways i got a used Greddy BOV on, and i've played with it a bit but the hiss doesn't really......well............hiss, after playing with the spring tension screw i kinda heard some hiss after rev the engine to near damn 7000 RPM now excuse my ignorance but isn't it supposed to hiss at lower RPM's????????????

and i was under the impression that it was supposed to be a clearly hear hiss, i mean i had to rev it hard to hear something and yes i can see the valve opening it's not like it's tightned to where the valve doesn't open, i was just under the impression that it should hiss louder and under a lower load on REV's???????

again it's Greddy BOV..........any ideas?????????????????

 

Techically speaking, if it is venting well enough... You may not even hear it. Its not supposed to make sound, its supposed to vent air. You should be able to put your hand in front of the exit of the bov and rev the motor and feel when it opens. Air should exit the vent tube. If not, its not opening. You will want to make sure you have it hooked to a correct vacuum source. If it is hooked up by the throttle body, then it may be hooked to a pressure only source.

 

If you're doing this just free revving the engine (by the sounds of it you are) then there won't be much positive manifold pressure to vent.....which equals low amounts of noise from the BOV.

 

This is what I'm understanding also. Does it make noise if you drive it and boost it?

 

hmmm it's what i thought according to classicauto's reply i have been "freerevving" since i have the car lifted currently cuz i'm still doing work on it, i haven't had a chance to drive it "underload" yet, but yes i have a buddy rev the engine and i can see the valve lift on when lifting off the gas on the vent.......ok thanks guys.

 

sounds like its working fine.