EFbomb

Maybe this is a newb question, but i was thinking about how a bov works, and i realized that since under boost the diaphram holds it shut, and it opens when you shift(hit vacuum) wouldnt it be open at idle-vac ?
and if it is open at idle, shouldnt we be putting air filters over it so nothing gets sucked in?
im just thinking of the ammount of vacuum force the motor creates at idle
(i put my hand over over the tb inlet on one of my zc's i was trying to start a long time ago and almost broke my hand cause it sucked it so hard duh), what if it was sucking that in the bov at idle...

sorry if this is a retarded question.... its friday

EFbomb

your kidding me ... nobody knows ?

B18 CYA

a bov opens at idle? ....uhhh.... the way a bov works is when you're in boost your throttle body is open and the turbo is forcing air through, then when u shift gears and let go of the gas pedal the throttle body plate closes therefore opening up your bov to release all the pressure thats left inside and preventing it from going back into your turbo compressor and ******* it up....

eg6T

its not open when idling,if you put your hand in front you wont feel a suck

Mase

if you're so concerned, tighten the screw.,

xrunner86x

i have a greddy type s and you can feel slight suction at idle, and it makes a sucking sound

Rory Breaker

Like SupaToona suggested, tighten the screw if you feel it leaking at idle.

beepy

My DSM BOV is open at idle. No problem, I just made it recirculating.

toolowsol

most bovs work by having a spring, when the charge pipe has boost, and the vacuuming tube has boost, they cancel each other out, so the only real force keeping the valve from opening or closing is the spring force. Now when you shift and the vacuum tube has vacuum in it, it is pulling up on the valve, and the boost pressure in the tube is pushing up on the valve, those two forces over power the BOV spring and open the valve. Now at idle, you have vacuum pulling up, but no boost pushing up. So you adjust the BOV so it stays closed. (force of the sping must be greater than the force of the vacuum pulling up) You do this by tightening the spring with a screw or adding washers. That way the only time it will open up is when you have boost pressure in the tube and vacuum in the vacuum tube.

EFbomb

thanks,
ILL huh... maybe well have to meet up somtime ill have my sol turboed by monday and hopefully drivable by next weekend. im in iowa

I asked because i was donated a DSM ig bov, and i dont know if their springs are very tight... it hissed at idle on my friends car when he took the recirc tube off.
i believe there is a way to crush the top of them so they hold a little better tho.



Modified by SBD at 10:54 PM 9/3/2004