2012 STI and want HKS SSQV blow off valve

babynoah2012

New member
hey guys so I'm getting a new 2012 STI next month.. on my 2008 STI i bought used and it came with a HKS SSQV BOV, i really liked it due to the fact that it was loud and i love the voice overtime i revved my engine........ will it hurt my engine to get it? or is there a way to get that loud BOV sound ??? please advice is greatly appreciated .. yes I'm a noob so please don't bash me i love STI and wanna learn everything but we all got to start somewhere right.. thank you very much
 

Spamby

Meat Product Toy
There is a few posts here about to BOV or not to BOV. There is also a nice write up that pertains to turbos and this has a part about BPV and BOV. Look for the stickies in the appropriate sections.

There is much debate whether it is safe to run a VTA BOV. Some so don't and others say it's ok.

I personally don't think i t is that huge of an issue but I did a little experiment sometime back. I got a COBB hybrid BOV/BPV. I left the vlave open for about a week and drove around hearing the phssssh noise. I did notice erratic idle, backfires, and sometimes near stalling, especially after sudden throttle lifts. Why is because you have just created a leak and expelling all of the air the MAF thinks is still in the system. Your system runs momentarily rich and the computer says WTF? Buck, snort pop and wooosh.

My opinion: For noise, it ain't worth it. I would rather have a nice idle and a happier engine than a loud woosh of air. A silencer delete and panel filter may get you the woosh you desire, albeit not as loud, from the BPV.
A CAI will also give you the noise but that is another debate.

In the end, it is your call and if you can live with the undesireables that may arise, Go for it!
 

IGOTASTi

System Operator
Staff member
No bashing will happen here. Welcome. I agree with Spamby, but to each his own. :)
 

babynoah2012

New member
thanx bro i appreciate it, i did like that noise but my STI gonna run me like 35,000 and i do not want to hurt my engine at all! i love the psshhhh noise like u said but, imma look into it, i rather have a nice STI like u said then to worry about wans gonna happen, plus my dads helping me buy it for my birthday and i DOUBT and i know hell get mad ass hell if i damage my engine.. thank you guys for the help and advice! much appreciated!! ill post pics as soon as i get t
 

IGOTASTi

System Operator
Staff member
Awesome. Can't wait to see it.
 

HolyCrapItsFast

Drinks beer!
You can use a BOV on these cars with good results but you need to know what you are doing and what you can do to reduce the effects. Though I highly recommend you maintain the use of a BPV, you can successfully use a BOV with no ill effects.

First you need to get a BOV that can be adjusted... I believe a true HKS SSQV is not user adjustable but there are knock offs that are. Second... You need to find a tuner that knows how to tune for it. You will here 90% of the people out there suggest that you can't tune for a BOV but they are wrong. With know-how you can tune out most of the effects of a BOV on a MAF car and obtain amazing drivability and shifting. :tup:
 
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Batmobile_Engage

Squirrel Meat Aficionado.
Staff member
You don't NEED a BOV to get a relatively loud BOV sound. Like Spamby mentioned, removing the intake silencer will help.
I personally noticed a huge difference when I removed the silencer a few years back. The sound is even more pronounced
with an aftermarket intake (cold air or short ram) and the stock BPV, believe me.

I run a BOV but I also have a blow-thru MAF, so I don't experience the typical BOV+MAF malfunctions. Personally, I feel
this is the best setup to run a BOV in, but that generally entails adding a front mount intercooler with a blow-thru boost tube.

To each his own, but I hope you don't put that BOV on there and go get a tune JUST to get the BOV working right. Seems like
a waste of money to me.

Lastly, I'm not familiar with the options you have with the SSQV, but maybe you could still use that valve and recirculate the air
in the same configuration as the stock BPV. Once again, removing the intake silencer or replacing the intake will make a recirc valve
much louder.

P.S. Don't go over to IWSTI.COM or NASIOC.com and ask about a BOV, you'll surely be flame sprayed.
P.S.S. Don't just slap an intake on the car without a tune. You could run lean and grenade the motor.
 

finallymysti

New member
if you want the sound and keep the warranty and safe engine get the spt short ram intake. it is a ton louder than stock and keeps the warranty and engine happy.
 

HolyCrapItsFast

Drinks beer!
You don't NEED a BOV to get a relatively loud BOV sound. Like Spamby mentioned, removing the intake silencer will help.
I personally noticed a huge difference when I removed the silencer a few years back. The sound is even more pronounced
with an aftermarket intake (cold air or short ram) and the stock BPV, believe me.

I run a BOV but I also have a blow-thru MAF, so I don't experience the typical BOV+MAF malfunctions. Personally, I feel
this is the best setup to run a BOV in
, but that generally entails adding a front mount intercooler with a blow-thru boost tube.

To each his own, but I hope you don't put that BOV on there and go get a tune JUST to get the BOV working right. Seems like
a waste of money to me.

Lastly, I'm not familiar with the options you have with the SSQV, but maybe you could still use that valve and recirculate the air
in the same configuration as the stock BPV. Once again, removing the intake silencer or replacing the intake will make a recirc valve
much louder.

P.S. Don't go over to IWSTI.COM or NASIOC.com and ask about a BOV, you'll surely be flame sprayed.
P.S.S. Don't just slap an intake on the car without a tune. You could run lean and grenade the motor.

Speed density is better and easier to implement. Both methods require a tune so why not plan your build to remove all of the limitations of the MAF altogether with SD versus changing hardware and piping to accommodate a BOV by relocating the MAF. :tup: Personally I would never recommend a blow through setup. They offer to many opportunities for instability.
 

Batmobile_Engage

Squirrel Meat Aficionado.
Staff member
Speed density is better and easier to implement. Both methods require a tune so why not plan your build to remove all of the limitations of the MAF altogether with SD versus changing hardware and piping to accommodate a BOV by relocating the MAF. :tup: Personally I would never recommend a blow through setup. They offer to many opportunities for instability.

What's the main issues you see with a blow-thru MAF? I don't seem to have any problems. Not trying to get off subject, just curious...
 

HolyCrapItsFast

Drinks beer!
Oh not of topic at all as it is related to using BOV's in maf applications. :tup:

It has to do with the flow of air over the MAF and the fact that the charge is under pressure while boosting and in vacuum when cruising. To understand why it is not ideal you have to understand how the stock MAF sensor works and what it is looking for as far as flow characteristics go.

The MAF sensor is designed to meter air that is either at atmospheric pressure or slightly less as air is drawn in at ever increasing velocity. It looks at the flow rate along with temperature to derive its mass. At the same time the ECU measures ambient atmospheric pressure and uses that to calculate the mass of air.

Now when you pressurize the air you make it more dense thereby increasing its mass yet the ECU is still making adjustments to fuel based on the flow of air past the MAF at atmosphere. This will offset the calculations the ECU has to do and it can be compensated in the tune provided the ambient to pressure transients are the same every time and the air itself remains consistent. This almost never happens and I have always found blow-through setup to be less stable

Of course I'm not saying it is a no go but I prefer either stock MAF location or SD. The results are always consistent and you don't have to over compensate for a condition the ECU is not equipped to handle. :)
 

Batmobile_Engage

Squirrel Meat Aficionado.
Staff member
I see your point and I grasp what you're getting at... However, at the same time, it raised a couple
of questions that have been bugging me all morning.

Please correct me if I'm wrong:

Physics/Fluid Dynamics states that with all variables (boost tube diameter, length, etc.), except pressure,
remaining equal in two identical tubes, raising the pressure in one tube would not cause the fluid moving inside
to flow faster than in the normally pressurized tube.

I seem to remember testing this in a lab in school one time and it holds true. However, IF that is ALWAYS TRUE
then why should the engine make more power with increased boost pressure? This shouldn't necessarily flow
more air/fuel to the cylinders.

We all know that increased boost pressures (and fuel added of course) makes more power...

So back to the original thought...if pressure doesn't affect flow, then I would think a blow-thru MAF wouldn't
read differently when pressurized.

The problem is, I believe what you're saying, that it DOES affect the MAF, I just can't figure out why...
 

HolyCrapItsFast

Drinks beer!
It is not that the pressure is effecting the flow. The flow rate remains the same over the MAF. So yes you are correct in that respect. But it is that the pressure has an effect on the density of the air in a volume which equates to mass. However the ECU calculates the information it gets from the MAF and thinks it is at atmospheric pressure or less. It doesn't know that the air is pressurized so an offset is induced because the ECU is basing its fuel calculations based on ambient atmosphere or less at the MAF.

So in a normal setup the ECU calculates air mass like this... it measures the flow rate and temperature across the MAF sensor in a known volume, Then applies ambient atmosphere, then calculates the inherent pressure drop as a result of flow velocity through a known volume as it is drawn through, then calculates the g/s as the outcome. In a blow through setup the g/s calculations are set off by the introduction of pressure. As mentioned this offset can be tuned for, but when conditions change, the ECU has a harder time compensating.

If it is working for you then I would leave well enough alone :tup:
 

Batmobile_Engage

Squirrel Meat Aficionado.
Staff member
I was tuned for in Florida (89*F), but I have recently moved to Michigan and its a frozen wasteland about now. It feels like I picked up 5-10 hp from
the cold air. I've been careful, worried that maybe with colder air I might run lean, but I'm probably nuts...what do you think?
 

HolyCrapItsFast

Drinks beer!
I think your fine. Temperature is fairly well compnsated for :eek: if you want you can give us a log and we can tell for sure.:thumbup:
 
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