Blowoff Valve!?
- Thread starter Danny5
- Start date
RockTheShazbot
New member
Kinda want a BOV like what my buddy had on his Mazdaspeed 6. Sounded like a horse sneezing 
Certifried
New member
We need someone to fabricate some FMICs too!
AxelRipper
Member
I think some other people should be able to back me up in saying that putting a to-air BOV will screw with a bunch of stuff in the engine to make it run like garbage. Yes, it sounds cool but it screws with the emissions, and when that happens it screws with normal operation of the engine.
If you want the BOV sound, get a piece of PVC pipe, an air compressor, a BOV, and some solenoids and wire it up. Can add a BOV to anything that way! (I'd post the youtube video, but I'm at work.)
If you want the BOV sound, get a piece of PVC pipe, an air compressor, a BOV, and some solenoids and wire it up. Can add a BOV to anything that way! (I'd post the youtube video, but I'm at work.)
I'd be willing to bet that the stock FMIC will be able to support just about all the power that you can wring out of this motor, unless you start swapping out internals. For a car with a tune and other basic bolt ons (exhaust, intake, etc), I'm going to guess the factory will be fine.
My concern would be if you added an aftermarket FMIC that's too large that it would cause a pressure drop that might actually hurt performance.
kinda want a bov like what my buddy had on his mazdaspeed 6. Sounded like a horse sneezing
Lol!
Danny5
Its over 39000!
I was betting you could tune for this. Nice!
/dreams of revving on people at stoplights
Certifried
New member
I was being sarcastic
If the turbo creates enough pressure to even need a BOV or FMIC, wouldn't something blow first?
Disclaimer: I know these terms, and I know generally what they do, and that's it. I'm in absolutely no way, shape, or form, a "gear head" (other than I did take high school auto 1 and 2).... (20 years ago)
Danny5
Its over 39000!
I was being sarcastic
If the turbo creates enough pressure to even need a BOV or FMIC, wouldn't something blow first?
Don't worry about lack of knowledge. Thats why you're here on the forum!
The 1.4 already has a FMIC. When you compress something, it gets very hot!!! Hot air is not good for a motor, (think pre-detonation) so to cool it, we run it through a radiator type device in the front of the car. This is the intercooler, and since its in front, we call it a front mount intercooler.
Any car that creates positive pressure needs a way to vent that pressure when you lift on the throttle. The resulting shockwave from a throttle closure would stall a compressor, in this case, the turbo.
This would cause huge lag when you got back on the throttle. To get around the compressor stall, we need to vent this additional pressure. Since it's already been through a metering device that measures volume, most turbo cars will recirculate the air back into the system before the turbo.
But old school turbo cars, that were carbeurated, didn't matter where you vented the air, so they vented this extra boost to atmosphere, and thus the bov, or blow-off valve, was born.
And as anyone knows, when you blow through a whistle, it makes a lot of noise. So what a BOV does is make noise when step off the throttle.
Obviously not everyone's cup of tea, but I grew accustomed to the whistling and chirping of my old school turbo.
Now, want to really start a good forum brawl, lets talk about anti-lag systems and how to add it to our little Sonic motors. LOL
Certifried
New member
I've got a Mitsu 3k VR4, yeah, I *love* the BOV on that baby
BoG233
New member
Don't worry about lack of knowledge. Thats why you're here on the forum!
The 1.4 already has a FMIC. When you compress something, it gets very hot!!! Hot air is not good for a motor, (think pre-detonation) so to cool it, we run it through a radiator type device in the front of the car. This is the intercooler, and since its in front, we call it a front mount intercooler.
Any car that creates positive pressure needs a way to vent that pressure when you lift on the throttle. The resulting shockwave from a throttle closure would stall a compressor, in this case, the turbo.
This would cause huge lag when you got back on the throttle. To get around the compressor stall, we need to vent this additional pressure. Since it's already been through a metering device that measures volume, most turbo cars will recirculate the air back into the system before the turbo.
But old school turbo cars, that were carbeurated, didn't matter where you vented the air, so they vented this extra boost to atmosphere, and thus the bov, or blow-off valve, was born.
And as anyone knows, when you blow through a whistle, it makes a lot of noise. So what a BOV does is make noise when step off the throttle.
Obviously not everyone's cup of tea, but I grew accustomed to the whistling and chirping of my old school turbo.
Now, want to really start a good forum brawl, lets talk about anti-lag systems and how to add it to our little Sonic motors. LOL
Thanx for the info I'm not a Turbo guy .I kind of new how it worked but the specifics I am sorely lacking . I have all ways rand a blower system . No big problems with Turbo just when I started all turbos had lagg Blowers had power at all times . Old school and misted the bout on turbos is all .
wingman
Active member
A BOVs’ function is to release excess boost pressure from the intake system when the throttle is closed. A perfect example of this is during on boost gear changes. Without a BOV, upon shutting the throttle, the pressurised air caught between the free-spinning turbo and the shut throttle is forced back through the turbine blades, this, in turn, forces the turbine to slow down or stall. This phenomenon is often referred to as “compressor surge” or “cavitation” and it places undue load on the turbocharger bearings, significantly shortening the lifespan of the turbo or even causing serious damage.
The secondary function of a BOV is to reduce the “turbo lag” effect between gear changes. Without a BOV, the compressor surge slows the turbine down, which then takes longer to spool up again when the throttle is opened. With a BOV, the excess boost pressure is released, keeping the turbine spinning and thus reducing the turbo lag effect.A BOV is usually mounted on the intercooler pipework between the turbocharger compressor and the throttle body, ideally on the throttle body side of the intercooler. A vacuum line connects the upper chamber of the BOV with a vacuum/boost source from the intake manifold. In its resting position, a spring holds the piston shut against the intake port.
Under boost with the throttle open, the blow-off valve remains shut. Upon shutting the throttle, vacuum is created in the inlet manifold, this vacuum combined with the pressure in the intercooler pipe forces the piston to open, releasing excess boost pressure in the intake system.
There are two main types of BOVs; atmospheric (or VTA – vent to atmosphere) and recirculating (Plumb Back). The difference between the two types is in how they dispose of the vented boost pressure.
Atmospheric BOVs vent the excess boost pressure out of the system into the atmosphere – hence the “atmospheric” name. These BOVs usually produce the much sought-after “whoosh” sound.
Recirculating or “Plumb-back” type BOV vents the pressure back into the intake system before the turbocharger inlet. They are practically silent compared to their atmospheric counterparts and are recommended for applications where the car needs to comply with noise or emission restrictions. They are also a good choice for off-road or rally applications where a sealed BOV system offers superior reliability and protection against damage caused by dirt, mud, sand etc.
The secondary function of a BOV is to reduce the “turbo lag” effect between gear changes. Without a BOV, the compressor surge slows the turbine down, which then takes longer to spool up again when the throttle is opened. With a BOV, the excess boost pressure is released, keeping the turbine spinning and thus reducing the turbo lag effect.A BOV is usually mounted on the intercooler pipework between the turbocharger compressor and the throttle body, ideally on the throttle body side of the intercooler. A vacuum line connects the upper chamber of the BOV with a vacuum/boost source from the intake manifold. In its resting position, a spring holds the piston shut against the intake port.
Under boost with the throttle open, the blow-off valve remains shut. Upon shutting the throttle, vacuum is created in the inlet manifold, this vacuum combined with the pressure in the intercooler pipe forces the piston to open, releasing excess boost pressure in the intake system.
There are two main types of BOVs; atmospheric (or VTA – vent to atmosphere) and recirculating (Plumb Back). The difference between the two types is in how they dispose of the vented boost pressure.
Atmospheric BOVs vent the excess boost pressure out of the system into the atmosphere – hence the “atmospheric” name. These BOVs usually produce the much sought-after “whoosh” sound.
Recirculating or “Plumb-back” type BOV vents the pressure back into the intake system before the turbocharger inlet. They are practically silent compared to their atmospheric counterparts and are recommended for applications where the car needs to comply with noise or emission restrictions. They are also a good choice for off-road or rally applications where a sealed BOV system offers superior reliability and protection against damage caused by dirt, mud, sand etc.
Certifried
New member
TURBOSMART didn't have the answer to that too?
LOL
If you're going to copy and paste from a website, at least reference it
TURBOSMART: How does a BOV work?
AxelRipper
Member
Stock tune requires a metered amount of air through the engine to be fully known, if it isn't (such as a BOV venting to atmosphere) then you have an unmetered air leak and check engine light comes on.
Also, I'm pretty sure the bypass valve isn't set to a certain pressure, but is controlled to control the amount of boost. I may be wrong on this one though (BNR could probably give more insight)
BoG233
New member
So you would need a duel port BOV to get the woosh and to keep the check engine light off . Right ?