BOV/BPV Thread
 

****Updated 2/2015 by @Inquisitive;! Thank you!***

BPV / BOV

A Blow-off Valve (BOV) or Bypass Valve (BPV) is a pressure release system present in most turbocharged engines. Its purpose is to prevent compressor surge, and reduce wear on the turbocharger and engine. Blow-off valves relieve the damaging effects of compressor "surge loading" by allowing the compressed air to vent to atmosphere, making a distinct hissing sound, or recirculated into the intake upstream of the compressor inlet. They provide improved / quicker throttle response, better boost handling capacity / higher clamping load to maintain boost pressure more reliably and quicker spool recovery.

A compressor bypass valve (CBV), also known as a pressure relief valve or diverter valve, is a manifold vacuum-actuated valve designed to release pressure in the intake system of a turbocharged vehicle when the throttle is lifted or closed. This air pressure is re-circulated back into the non-pressurized end of the intake (before the turbo) but after the mass airflow sensor.

A blow-off valve, (sometimes "hooter valve", not to be confused with a bypass valve) performs the same task but releases the air into the atmosphere instead of recirculating it. The blow-off action produces a range of distinctive hissing sounds, depending on the exit design. Some blow-off valves are sold with a trumpet-shaped exit that intentionally amplifies the sound. Some turbocharged vehicle owners may purchase a blow-off valve solely for the auditory effect even when the function is not required by normal engine operation. Motor sports governed by the FIA have made it illegal to vent un-muffled blow-off valves to the atmosphere.[citation needed]

Blow-off valves are used to prevent compressor surge, a phenomenon that readily occurs when lifting off the throttle of an unvented, turbocharged engine. When the throttle plate on a turbocharged engine closes, the high pressure air in the intake system is trapped by the throttle and a pressure wave is forced back into the compressor. The compressor wheel slows rapidly and may even stall, and the driver will notice a fluttering air sound. The rapid slowing or stalling stresses the turbo and imparts severe turbo lag if the driver accelerates immediately after the surge event.

Disadvantages
In the case where a mass airflow sensor (MAF) is used and is located upstream from the blow-off valve, the engine control unit (ECU) will meter out excess fuel because the atmospherically vented air is not subtracted from the intake charge measurements. The engine then briefly operates with a fuel-rich mixture after each valve actuation.

The rich mixing can lead to hesitation or even stalling of the engine when the throttle is closed, a situation that worsens with higher boost pressures. Occasional events of this type may be only a nuisance, but frequent events can eventually foul the spark plugs and destroy the catalytic converter, as the inefficiently combusted fuel produces soot (excess carbon) and unburned fuel in the exhaust flow can produce soot in the converter and drive the converter beyond its normal operating temperature range.

An alternative method for utilizing both a MAF and a blow-off valve is to have the MAF located down stream between the intercooler and the throttle plate. This is known as Blow-through rather than the traditional Draw-through set up. Care must be taken as to the position of the MAF to prevent damage to the sensitive element. (I.E. on a SR20DE motor, the MAF must be at least 12" from the throttle plate, and the blow-off valve must be 6" from the MAF sensor). By using a draw-through method, the MAF won't be affected by the blow-off valve opening as the pressure is vented before the air reaches the MAF.

One approach used to mitigate the problem has been to reduce the boost pressure, which reduces the required venting volume and yields less charge over-calculation by the ECU. The air can also be recirculated back into the intake, a typical stock setup for cars with an upstream MAF sensor. The situation can also be corrected by switching the fuel metering system over to a manifold absolute pressure sensor, a conversion that usually requires a compatible aftermarket ECU or piggy-back fuel controller. The MAP sensor monitors the absolute pressure in the manifold at all times and will correctly detect the change that occurs when the valve vents, allowing the ECU to reduce fuel metering accordingly.

Operation
A blow-off valve is connected by a vacuum hose to the intake manifold after the throttle plate. When the throttle is closed, the relative manifold pressure drops to below zero bar and the resulting pressure differential operates the blow-off valve's piston. The excess pressure from the turbocharger is then vented into the atmosphere or recirculated into the intake upstream of the compressor inlet.

FYI
Most BOV/BPV will need some maintenance through the years. Basically they need to be re-oiled.

The following list will be discussed below with images:

• Forge (both V1, V2 and unknown versions purchased) BPV
• Turbosmart Dual Port BPV / BOV Combination
• Go Fast Bits (GFB) Respons BPV / BOV Combination
• Forge V2 BPV
• Forge V1 BPV
• HKS SSQV BOV
• CorkSport (CS) MZR BPV
• Cobb XLE BPV / BOV Combination
• Synapse Synchronic BOV
• Forge V? BPV
• TurboXS BPV
• Tial QR BPV
• Turbosmart Kompact Plumb Back BPV
• GReddy RZ BOV
• CX Racing BOV (comes with their FMIC)
• JBR DISI Bypass Valve Return Hose
• Synapse Synchronic DV

Turbosmart Dual Port Maz Type 5 BPV / BOV Combination
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237360
Billet aluminium; Holds boost more efficiently over stock valve; BPV spring rate is tuneable to the vacuum of your car; Choice of high pressure and low pressure springs; Gain Top End Horsepower; vents to intake, atmosphere becoming a blow off valve or adjustable mixture of both, while the Sleeper version is quiet during mild boost; note: both are taller, therefore, will not work with stock air-box
Available from: Turbosmart Dual Port Maz Type 5 BPV / BOV Combination
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $482.96

Go Fast Bits (GFB) Respons BPV / BOV Combination
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237419
Dual action, twist BPV to BOV adjustable
Available from: Go Fast Bits (GFB) Respons BPV / BOV Combination
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $268.68

Forge BPV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237508
Made from billet aluminium
V1: Makes a ping / swords clashing noise
V2: stealth
Available from: Forge BPV
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $169.95

HKS SSQV BOV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424335674
Info: http://www.hksusa.com/
Nickel-plated, die-cast metal secondary valve, which is swaged to the primary valve, a stainless steel C-Clip and spring to increase sealing and durability; First Sequential Blow-Off Valve featuring a unique, pull-type, sequential valve structure and a differential pressure control system allowing for stable operating ranges from low to high boost pressures. Note that a separate flange must be purchased and fitted to the BOV before installing on your car; comes with inline filter on the vacuum line; can keep closed at idle. The recirculating kit is an optional extra (additional expense), but note that 100% VTA can damage your CAT.
Requires a separate (extra cost) mounting flange kit which is difficult to install properly (ex. CP-E, Jay Racing / JSC Speed, etc.)
http://www.mazdaspeedforum.org/forum/foru...1&d=1424335847
Available from: Hasegawa, Kitagawa, and Sigma (HKS) SSQV BOV
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $331.95

CorkSport (CS) MZR BPV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237643
Half the spring height, 30% larger piston, 33% faster to vent
Available from: CorkSport (CS) MZR
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $188.99

Cobb XLE BPV / BOV Combination
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237678
Different vent modes, pre-load adjustable, compatible with alcohol / water mix, reliably holds high levels of boost without leaks, fast venting, Teflon coated, hard anodized piston providing low sliding friction, reduces surface wear and minimizes maintenance requirements, can hold up to 60 psi
Available from: Cobb Tuning XLE BPV / BOV Combination
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $295

Synapse Synchronic BOV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237712
Eliminates the need for diaphragms by using a piston actuator that does not require frequent lubrication; can hold 60 psi yet still prevent compressor surge; can install as pull or push type valve
Available from: Synapse Synchronic BOV
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $289.95

TurboXS BPV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237751
Each flange is beefy to keep it from warping and allowing you to have the best mating surface possible
Available from: TurboXS BPV
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $239

Tial QR BPV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237783
6 spring options (3 PSI to 12 PSI)
Available from: Tial QR BPV
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $259 silver, black, red, purple, blue

Turbosmart Kompact Plumb Back BPV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237817
Available from: Turbosmart Kompact Plumb Back BPV
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $184.49

GReddy RZ BOV
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237850
Easily adjustable to eliminate compressor surge and preventing premature boost leakage while increasing boost response between shifts; made of durable cast and billet aluminium frame; valve to diaphragm ratio provides performance that cheap piston types cannot offer; spring stiffness adjustment screw; three models
Available from: GReddy RZ BOV
MS6 (?), MS3 Gen1 (?), MS3 Gen2 (? Although several Genpu owners have installed this) $360 for Type FV for RX-7

CX Racing BOV (comes with their FMIC)
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237882
Available from: CX Racing BOV (comes with their FMIC)
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $399

JBR DISI Bypass Valve Return Hose
http://www.mazdaspeedforum.org/forum/foru...1&d=1424237913
Direct (5 layers silicone & 4 layers of reinforcement) replacement for OEM, which will show signs of deterioration and cracking within a year degrading performance to eventually throwing a CEL.
Available from: JBR DISI Bypass Valve Return Hose
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $35 in red, blue, black or white

CP-E Helihose
http://www.mazdaspeedforum.org/forum/foru...1&d=1424335925
4-ply reinforced silicone hose, helical cut throughout for flexibility, steel wire routed through the hose to prevent kinking, while maintaining extreme flex, two SS liner clamps are included, providing clamping pressure without tearing silicone, gloss silicone finish with CP-E logo, 14.5” in length, made in the U.S.A., lifetime warranty
Available from: CP-E Helihose
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $64.48

CorkSport (CS) DISI Silicon Bypass Valve Hose
http://www.mazdaspeedforum.org/forum/foru...1&d=1424335989
Made from long lasting, four-ply reinforced, high quality, molded silicone for a strong flexible connection for ideal flow from the bypass valve to the turbo inlet pipe, comes in black, red, blue or white with two T-Bolt clamps
Available from: CorkSport (CS) DISI Silicon Bypass Valve Hose
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $39.99 in black, red, blue or white

Synapse Synchronic DV
http://www.mazdaspeedforum.org/forum/foru...1&d=1435169446
Eliminates the need for diaphragms by using a piston actuator that does not require frequent lubrication; can hold 60 psi yet still prevent compressor surge; extremely fast response (< 25 msec) to eliminate compressor surge, 6061 aluminium, use a bolt on adaptor or weld Al or SS flange
Available from: Synapse Synchronic DV
Caps for Synapse Synchronic DV
MS6 (Yes), MS3 Gen1 (Yes), MS3 Gen2 (Yes) $282.95; standard black cap (or colours: blue, red, orange, raw - add $29.99)

Nice write up!

This should be made a sticky

@Raider will probably merge it into the NEWB thread.

Actually waiting for him to add it.

Sorry, actually Just saw this. Can you add Forge v1 and v2? Blue springs no shims. Oh and this is. Sticky. Will mess with the main thread in the am. @RhoadBlock to updated the newb thread.

I'll throw $ your way when I get to a computer.

blue 2 shims you mean, killahpanties.

For me, no shims. Wild.

I will work on it tomorrow at some point. I'm finishing some Christmas shopping. Hope it's okay for now.

Very nice, detailed write-up. This will be great. We better not have any more threats with questions concerning this matter.

I will add a link to where these can be bought from. Thanks for the input guys..

Good write up Ryan,

A few spelling mistakes and grammar mistakes but overall well done.

Just a few quick things I saw....... (all my own personal suggestions)

Many videos are available to help you decide between which sound you would like for your car.

*purchase
**separate

BPV/BOV

lolwut?

How about pick one or the other inefficiently combusted fuel or unburned fuel.

It should be chosen. Lose an "o"

/ Grammar Nazi.

^ lol nice

Adding it to the Newb thread now.

@irishking03 also, change the Forge link from a link to a pic. And I'd put a one or two line gap in between each brand, just so all the pics don't run together. You don't necessarily have to add a link to each one if you don't want to. You can probably just mention at the top that most, if not all, can be purchased from several of the forum vendors. Just link the Vendor Section or something. Good work bro.

Thanks Pal. I will fix. I kinda just through this together and forgot to look over it. Im trying to do it but I just got laser eye surgery last night and I cant quite look at the computer for to long with out my eyes bothering me. But as soon as I can I will change this.. Thanks again

I added Forge Photo.. I added a line after each company branded BPV.. WIll edit tomorrow. Eyes are bothering me a bit tonight.. A little off topic but laser eye correction was done yesterday morning and my shit is all dry.. "NO HOMO"

@irishking03
Just figured Id throw my .02, my HKS came with a flange already mounted and a direct bolt on cost a lil more but well worth the simplicity. Dont want to get newbs confused if they run into it online. Also might want to put that most of these bov/bpv need regular maintnence, re-oiling(the hks dosnt)

Nice thing about hks and mounting the flange yourself is that you can "clock" the hks before tightening down the snap ring so the vacuum inlet does not rub the hood and align the hks body to not rub the oem shroud cover if still using stock tmic.

Hks comes with an inline filter on the vacuum line.

The cpe helihose is a great replacement recirc hose as it is flexible and reinforced with copper wire.

The flange mine came with allows for 360 degrees of rotation.

Yes you can rotate 360* but once the snap ring is set completely, the hks should not move. Thats how my flange kit worked. If it does, then a leak could occur since the seal should be tight on the flange. What kit do you have? I bought the cpe kit which uses the hks snap ring. Maybe yours is different, idk.

Oh for sure once the ring is in place that son of a bitch is fucking solid lol. As to what brand Im not sure. I bought it from a non msf vendor n its only description was that it was 2010 specific. Looks almost exactly like the photo up top.

Haha! Ya you had me wondering what kit allows for 360* movement when installed. But since yours is solid, its all good.

Maybe add a description of the stock BPV. It's a dual-chambered design, and works really well as long as the glue seal on the top doesn't leak.

I can provide pics of the stock BPV I have disassembled in my garage.


Tapadatass

I will add that later today when I get a chance.. Thanks

do it.. Thanks man.

Just added note in RED that says basically you can buy the hks from a few vendors and add the flange and recirc kit.

Doesn't Synapse have a BOV for the DISI? Or was there a fallout I missed back in the day?

http://synapseengineering.pinnacleca...acturer&mid=12

I will add it just incase someone does come across it.

Can anyone confirm that the cobb tuning xle bpv Model#771650 for the mazdaspeed 3 is the same as the cobb tuning xle bpv Model#724650 for the Subaru Impreza WRX 2008-2012? They look identical on cobb's website. I would save almost $50 online if I purchase the wrx one from here:

Cobb tuning 08-10+ WRX and 05-09 LGT , Engine Performance, Subaru 2008+ WRX / STI performance parts, Subaru Performance

If this has been covered already I apologize...

I was running that on my car for a while.

Excellent valve, holds up to 60 psi and is very fast.

usename Robry has it on his car now.

a few posts up, I asked a question about the cobb xle valve. Whats your take, you think its the same as the wrx one?

Also, how are you running it? with full circulation, does it make any sound?

It is a high quality bpv, without a doubt. I bought it because I like Cobb products, and it is specifically advertised as being meth resistant.

I'm running it in full recirc.

It does make a sound, but not quite as loud as a full VTA BOV would.

If you have an open element intake such as an sri or cai, that is what lets most of the sound out of the intake system from a bpv.

I'm not sure whether or not the dimensions for the wrx and the mazdaspeed are the same on the flange, so I can't tell you for sure whether or not the xle for the 2 applications are identical.

Edit: see post below

^ my forge v1 and stock bypass worked fine on my friends legacy gt so i don't see why the cobb xle shouldn't work

@codyb154

this is awesome - thanks so much

i like the cobb xle -- AWESOME

Any suggestions for a Forge V1 with CP-E nano and turbo inlet? which spring / shim combo? Thanks!

Holy crap. Search button lol.

Sent from my T-Mobile G2 using Tapatalk

Great thread. Thanks :)

Thanks for thread good info

I am currently in the market and finalizing all the paperwork for my 2011 ms3. I already have a small list of parts I am looking to buy without voiding warranties. The only part that I have been reading about and sort of worried about is the BOV. I am leaning towards the turbosmart dual port 50/50, my friend has this exact piece but I think I would like to hear a little more from a forum. I know I can run full recirculation, but I also want to know that if I keep it 50/50 will my car run rich? It will be my first modification to the car along with a corksport stage II short ram intake. I am worried about the car running rich and causing ecu problems them eventually totally ruining my car. So any information would be greatly appreciated. I was also wondering if any lights on the dash come on such as engine check when you put on the BOV.

Thank you

Future ms3 lover

You need to worry about other shit before you worry about a bov/bpv, the stock one is fine until you up the boost levels a lot. Get more mods first that matter, that should be down the road.

~Sent from my GNexus running Aokp~