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Discussion Starter · #1 ·
Just curious since I'm just starting to get into engine modding...do all turbos have to have the blow off valve sound, or can that be silenced without losing performance?
 

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you can recirculate the BOV back into the intake.. you can also get a bosch bypass ( what alot of cars have stock) they're quieter both of them will keep it quiet er

what i'm doing with my setup is recirculating it
 

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This would be a good question for Turbokits to answer, from what I know is the purpose of a Blow Off Valve is to prevent damage to the turbo when the Throttle Plate Closes and the pressure inside the intake tube works its way back to the turbo, and slows the blades rapidly this creating stress on the turbo.

There is another device that instead of releasing that "trapped air" into the atmosphere it recirculates it back into the unpressurized end of the system (before the turbo)

personally, I love the sound from a BOV.

I hope im not giving wrong info here.
 

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Discussion Starter · #4 ·
I just dont like the high pitched whistle I hear from some turbos. If I can make the engine sound as mean as it performs, then I'm fine with a BOV if it doesnt whistle.
 

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There are also different shaped valves for different "sounds"
 

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I've was next to an STi in traffic once that had a BOV that sounded like the pressure relief on a semi truck's air system. RICE. I never heard the BOV on my Mazdaspeed 6, so I know it can be done quietly.
 

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I've was next to an STi in traffic once that had a BOV that sounded like the pressure relief on a semi truck's air system. RICE. I never heard the BOV on my Mazdaspeed 6, so I know it can be done quietly.

ya but the power and size of the turbo in an STi as compared to a Mazda 6 is night and day....so i guess seeing as we are now comparing a Forte Koup to an STi i guess it can be done but... i too love the sound of the BOV
 

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ya but the power and size of the turbo in an STi as compared to a Mazda 6 is night and day....so i guess seeing as we are now comparing a Forte Koup to an STi i guess it can be done but... i too love the sound of the BOV
MazdaSpeed 6 = 276HP, not far off of the STI's ratings. And, to clarify, the "power and size" of the turbo have very little to do with the sound of the blowoff valve. The sound created by the BOV is dependent entirely on the BOV itself.

A larger turbo and/or running more boost will increase the sound of the turbo, but that's it. The hissing noise it makes while it is spooling will be different. Other factors, such as heat shielding and placement in the engine bay, will also impact this noise.

To address the OP's concerns, the simple solution here is to get a quiet BOV and or get a bypass valve (also called a recirculation valve). Both will prevent compressor surge- the primary difference is that the BOV vents to atmosphere (and that effect is often enhanced by the design of the BOV), whereas the BPV recirculates the air back into the intake system.

Coles notes: if you don't want your turbocharged car to whistle, don't buy a HKS SSQV or similar BOV. That's as complicated as it gets.
 

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Also another way to go if you don't want that whistle is a supercharger. It whines but will never blow off due to it being integrated into the system. also you won't have to worry about over boosting, the boost is very reliable in a supercharger, and you will get crazy low end torque and good hp.....but if you want a turbo, 1. a recirculating bov, takes the excess boost and instead of venting to the air it goes right back into the intake pipe after the filter, before the turbo, and a atmospheric vents right to the atmosphere, some of the recirculating you can hear...barely, but there is no such thing that i have heard of a "quite" atmospheric bov, so in my opinion recirculating is the way to go....the good thing with the forte is that well in my case on the 2.4 sx there is no MAF sensor so it won't mess with the fuel mixture which ever way you go... because on some cars that do have MAF sensors you have to do a blow through type MAF on the cold pipe, so that it measures the air flow coming in after the blow off valve, because you lose air when it blows out the excess...so if you do have a MAF i would stay with the recirculating .....
 

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Also another way to go if you don't want that whistle is a supercharger. It whines but will never blow off due to it being integrated into the system. also you won't have to worry about over boosting, the boost is very reliable in a supercharger, and you will get crazy low end torque and good hp.....but if you want a turbo, 1. a recirculating bov, takes the excess boost and instead of venting to the air it goes right back into the intake pipe after the filter, before the turbo, and a atmospheric vents right to the atmosphere, some of the recirculating you can hear...barely, but there is no such thing that i have heard of a "quite" atmospheric bov, so in my opinion recirculating is the way to go....the good thing with the forte is that well in my case on the 2.4 sx there is no MAF sensor so it won't mess with the fuel mixture which ever way you go... because on some cars that do have MAF sensors you have to do a blow through type MAF on the cold pipe, so that it measures the air flow coming in after the blow off valve, because you lose air when it blows out the excess...so if you do have a MAF i would stay with the recirculating .....
Superchargers can be equipped with BOV's, and for smaller motors like what's in the Forte, a supercharger won't provide as much power as a turbocharger would for the same price point.
 

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Superchargers can be equipped with BOV's, and for smaller motors like what's in the Forte, a supercharger won't provide as much power as a turbocharger would for the same price point.
true .. superchargers are generally more expensive , and BOV's can only be put on centrifugal Sc's

for instance the supercharger I have on my car is 2400 new.. you can do a whole turbo setup for that price.. if you go custom
 

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ya this is true (im a turbo kinda guy) but he said he didn't want a blow off "noise" so why would that be such a bad thing...and you can get a good amount of hp and torque if you have the right setup and pulleys....
 

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ya this is true (im a turbo kinda guy) but he said he didn't want a blow off "noise" so why would that be such a bad thing...and you can get a good amount of hp and torque if you have the right setup and pulleys....
oh you don't have to tell me that ;):cool:

me personally I just don't like being so obvious so I want to recirculate it just to quiet it down
 

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I just dont like the high pitched whistle I hear from some turbos. If I can make the engine sound as mean as it performs, then I'm fine with a BOV if it doesnt whistle.
my friend got a german BOV in his Corolla S, sounds positively mean.
best sounding bov I've ever heard.
So yeah, there are tons of choices as to what you can make it sound like.
STI's sound pretty b.a. too
 

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Discussion Starter · #15 ·
Awesome, thanks guys for your answers. Didnt know I'd get so many lol. Corytate, do you know what company makes that BOV, if it sounds as mean as you say and they make one for the Koup I may buy it.
 

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what kinda of sound are you looking for.. my BOV just sounds like chshhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
 

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Awesome, thanks guys for your answers. Didnt know I'd get so many lol. Corytate, do you know what company makes that BOV, if it sounds as mean as you say and they make one for the Koup I may buy it.
I will ask him this weekend when I see him and get back to you.
He got his turbo kit at turbokits.com then bought the BOV separately, can't remember where
I'll get back to you though
 

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what kinda of sound are you looking for.. my BOV just sounds like chshhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

LMAO... how does that sound again?
 
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