I just found out that the wrx doesn’t have a bov. I have a 90 eclipse gsx, and i was just wondering how this works, i just thought that it was needed to release the pressure, but i guess i’m wrong now. an explanation would be appreciated. Thanks
So it’s just a valve that opens and lets the air back. because my car is recirculated but it still has a bov. Are the subaru’s just silent or something.
Yes… Remove the silencer snorkus and you will hear the BPV.
It most certainly has a bypass device it sits on the intercooler and stares you in the face everytime you open the hood.
Who wants to hear the car sneeze over that engine anyway? RobY’s almost geve me a chub listening to it.
BOV’s arent necessarily required.
Tons of factory cars came without them.
Grand Nationals get into the 10’s without them, easily.
That scooby though, has a BPV
I think it holds up to something like 20psi so theres no need to replace it until you get a new turbo.
Your car is recirculated or vented to atmosphere. If you’re valve is directed back in into the intake, then it’s recirculated. People run GReddy BOV’s that are still recirculated:
The whole point of a blow off valve is to vent the air compressed by the turbo from the piping, so that it isn’t forced back through the turbo when the throttle body closes. Atmospheric BOVs are typically run on non-factory turbo cars (hondas). All factory turbo cars (DSMs/Evo/Subaru/Audi etc. except GNs) come recirculated from the factory.
Subaru’s valve is esentially the same thing as the 1g DSM valve, and it is very quiet, as there is a ton of intake plumbing and extra crap in there to keep noise down (intake silencer located in the fender).
buick grand nationals never came with them, neither did typhoons and syclones, and they have been running around for 20 years with no problems. There are a bunch of guys making 1000+hp with 80+mm turbos and no BOV. The whole myth that you will grenade a turbo without a BOV is total BS, but it gets plenty of guys to spend 200 bucks to hear that stupid sound 
bov eliminates compressor surge
this is what i was told, so if its wrong, fell free to correct me
Imagine your throttle plate suddenly closes after boosting. any residual air left slams into the throttle plate, and bounces back into the turbo, creating a chattering noise known as compressor surge. Its the equivalent to bitchslapping your compressor wheel. Its not that dangerous to low CFM turbos, but repeated compressor surge on a High CFM turbo will f**k it up hardcore
edit: i just read n20junkies post, so i guess i was wrong :gotme:
I was laughing at the title before the video even loaded. LMAO
Yeah that was what i was thinkings, what white00s10 said, but when i was told by someone that thier wrx didn’t have a bov i was confused. they just don’t have a “bov” but something that works just like it. Thanks for clearing it up.
BOV’s are the hotness yo.
SSSSSSSSSSSSSSS PSSSSHHHHHHHHHHH
Thats the only reason I bought a turbo car!!!
/sarcasm
this ones even better… with road test.
http://www.nyspeed.com/forums/showthread.php?t=14491
Hey, read this thread, I knew BOV’s did something
Let’s take a quick look at the BOV (Blow Off Valve) and what it does for you and your car.
First, a quick history lesson.
Q. Where did the BOV come from, who could possibly have made something that sounds so cool?
A. Porsche, Duh. Developed for there race cars (early 80’s i believe) it was patented as a Pop Off Valve. You may still hear some old timers refer to it as such. (AWDrifter)
There, now you have learned something today, and can wow your drunken friends at the bar.
Ok, let’s take a look at what this little gizmo does.
The BOV releases the pressurized air from the intake pipes when you lift your foot off the throttle; either to shift, or just to hear the cool sound.
Now, why do we need to do this? To taunt others in to racing? Just because it sounds cool? Possibly, who knows with those Germans; those may have been underlying reasons, but actually the intended purpose was performance.
When you lift your foot the throttle plate closes, and that air bounces off the throttle plate and makes it way back towards the turbo. When that air gets back to the turbo it will try to spin it backwards (compressor surge).
Now when you reopen the throttle the turbo has been slowed, or even stalled, and needs to be reaccelerated. With a BOV in place, this air would never make its way back to the turbo, and the turbo would be able to continue spinning freely. Now when you get back on the throttle your turbo is still spinning from before, and will spool more quickly.
Lets take a look at BOV placement.
Some will argue that it should be near the throttle body, others say closer to the turbo.
Well, lets look where Porsche put it on their race cars.
Porsche made the BOV part of the compressor housing, and redirected the compressed air to the turbo inlet. Pretty slick, huh?
I am from the close to the turbo camp, and i will explain why.
- The air doesn’t just bounce back off of the throttle plate, there are sharp bends in the pipe, and a giant obstruction called an intercooler in the way.
- By placing it near the turbo you vent only the air that has made it back to the turbo, leaving the rest of the pipe with some pressurized air still in it.
- Having the BOV after the intercooler vents air the ic has already cooled. Kind of a waste, dont ya think?
Placing the BOV near the throttle body seems to be out of ease. Just like the boost pressure reference nipple being on the turbo housing. (We all know pressure in the housing is not the pressure in the manifold) It was just easier, and less costly that way.
Now i am sure you have been reading this and saying to yourself “Hey, i thought the BOV was to keep the turbo from getting surge and damaging it.” It does do that, but that was not its original intent.
And that my friends is the BOV and you.
i’m not sure if my logic is right with placement. perhaps newman or some other train drivers can shed some more light on it.
Yes thanks once again. I knew the purpose of a bov and the function like you stated above. But when some guy called me an idiot for thinking his wrx needed a bov, i was a little insulted. So thanks for the reply’s
actually Mr. Daze of Zero u are correct…with non-intercooled applications turbo placement also has a factor…cause lets face it…on a STS Rear-Mount FBod kit the tubo is miles from the throttle plate also reducing the effect the charged air might have on the turbo…Y didnt GM put them on their cars…well they are GM and in the mid 80s early 90s they could prolyl careless…does not having a BOV or ReCirc valve mean ur gonna kill ur car or turbo…NO it just aids in extending the life
that wasnt for you, so much as it was for the people that didnt really know the BOVs intended purpose.