What is a BOV?

Sarge · rice boy Joined: 27 Nov 2002 Posts: 31

I am not a complete deadshit, i know it means blow off valve, but what exactly does it do? and what kind of preformance does it deliver, and how much $$?

BlueTC · petrol head Joined: 22 Oct 2002 Posts: 1148

Commonly found on EFI Turbo motors,

BOV pevents charged air from turbo to throttle body when closed (to change gears) does not re enter the compressor housing and cause backspin to the turbo,

so in english vents charged air into the atmosphere when the throttle body is closed, to help the life of the turbo

Im sure Gene will have a more understandale explanation

regards

Sarge · rice boy Joined: 27 Nov 2002 Posts: 31

after reading it 3 times i undastood it Very Happy

so do you put these on seperatly or do they come on a turbo, if they come seperatly, how much $?

peteymate · tinkerer Joined: 15 Aug 2002 Posts: 306

no they dont come with a turbo, but depending how much u want to spend, i think u can get them for about $180 upwards

Sarge · rice boy Joined: 27 Nov 2002 Posts: 31

cool, thanx for the info

cheers

BlueTC · petrol head Joined: 22 Oct 2002 Posts: 1148

Me im not going to say a price

but there are many different ranges like:
Turbosmart
G REDDY
HKS
Trust
RBR
GFB

the reason why i dont say a price is cause im not a sales person and dun wanna get sued for givin false info

regards

Sarge · rice boy Joined: 27 Nov 2002 Posts: 31

man, no one round here is going to sue shit Razz

we're all after a bit of helpful info, the most that will happen is someone will come and say "you wanka, it wasn't $15 it was fucken $3500" Razz

Gemini Driving Yobbo · petrol head Joined: 26 Feb 2002 Posts: 3897

i saw a BOV at autobarn today for $160

please dont sue me

Gold TX Sleeper · backyard mechanic Joined: 05 Feb 2002 Posts: 509

A blow off valve is used to help keep the boost pressures high inside the inlet tract/piping to the throttle body. They are normally fitted somewhere in the piping between the throttle body and compressor outlet side of the turbo. They are bassically a mechanically operated diaphram that vents/bleeds excess boost inside the inlet to the atmosphere. On an M.A.F sensor equipped engine the excess boost is plumbed back into the inlet of the turbos compressor to be recurcuilated through the turbo, there is a good reason for this but to keep the post shorter i'll leave it out (bassiacaly it's a computer thing). On a M.A.P sensor equipped engine the excess pressure bled by the B.O.V can be vented to the atmosphere.
O.K, when a turbo spools up, the boost pressure is sent from the turbo, through the piping to the throttle body. When the throttle body is open, the boost has somewhere to go - inside the engines combustion process. But when the throttle body is closed suddenly (as BlueTC stated during gear changing) the excess boost has nowhere to go inside the inlet piping. Under high boost applications it has two choices 1) slowly bend/damage the butterfly in the throttle body to get into the plenum, or 2) revert backwards into the turbos compressor. If it reverts back into the comressor it slows the turbo down resulting in lost boost and damage to the turbos compressor wheel.
Picture having a tiny fan on full blast, then picture putting a bigger one facing it on full blast. The bigger one will slow the smaller one down due to the higher air flow being forced upon its blades.
This is where the B.O.V comes into play, inside it there is a diaphram operated by a spring set at a certain pressure. When the boost pressure inside the inlet suddenly rises due to a sharply closed throttle butterfly, the excess boost is vented out through the B.O.V. So when you snap into the next gear, your turbo will have an easier time building the required boost and your throttle body butterfly will survive alot longer.
They are bought seperately, from places like AutoBarn (where the hell did Yonnee disappear to?) and various turbo specialists. They range in prices from about $100 all the way up to an overpriced $500. Turbo Smart is an Australian company that has a wide range as do G.F.B (Go Fast Bits). They regularly advertise in Hot 4's and Fast Fours with a small catalogue and supplier locations.
Man i gotta cut down on the caffeine!!! These posts are getting longer, but at least they're completely answered i spose. If anyone finds any faults in this post, please point them out so this guy gets the right info.
Cheers,
Jasyn...

MR_GEMI · Posted: Tue Dec 03, 2002 9:56 am Post subject: Re: What is a BOV?

mate that was one of the best posts ive ever seen!!
_________________

peteymate · tinkerer Joined: 15 Aug 2002 Posts: 306

hahahhahahahahahaha

beasty · tinkerer Joined: 07 Oct 2002 Posts: 88

You can pick up BOV's from as cheap as $45 brand new these BOV's come factory fitted on SAAB's and are the only BOV's the cops cant touch. because the don't release the gases back into the atmospher these are the ones the plumb back into the front snout of the turbo

beasty · tinkerer Joined: 07 Oct 2002 Posts: 88

You can pick up BOV's from as cheap as $45 brand new these BOV's come factory fitted on SAAB's and are the only BOV's the cops cant touch. because the don't release the gases back into the atmospher these are the ones the plumb back into the front snout of the turbo. They are made by bosch.