Now that turbos are on the market, I thought it might be a good time to talk about the different blow off valves on the market. Philodox has the GReddy Type S BOV. The GReddy car (shawrf1's car) has the new GReddy Type RS, and the PTP turbo car has the HKS SSQV.

I was looking at the Tial BOV, but from what I've read it might be too big for the level of boost we're running. Here's the list of contenders. Anybody with thoughts and experiences or sound bites, post them.

GReddy Type S
GReddy Type RS
HKS SSQV
Blitz Super Sound
Tial
TurboXS RFL

here is a page that has some sound/video clips to various BOV's...enjoy:D

http://www.935motorsports.com/bovmedias.htm

anyone prefer one over the other? To me i prefer the one that looks like the sliver bullet it looks cool haha....other than that i dont know the differences

Doesn't Tial have different sized BOVs? Also see what Turbosmart has to offer.

The only thing I know for sure about these devices is they relieve pressure on the compressor side, preventing damaging compressor surge. Plus, they make an awesome "pfft" sound. :D

whats the alternatives to BOVs..

I love the BOVs sound..send chills down my spine..

I prefer the louder ones, so definitely the Blitz would be my pick.

HKS Super SQV
http://www.hksusa.com/products/?id=792

"The HKS Super Sequential Blow-Off Valve (SSQV) is a dual stage pull-type relief valve. Unlike typical push type blow-off valves, the SSQV will not leak under any level of boost because the boost pressure in chamber "C" keeps the valve closed against its seat. The SSQV releases excess boost when there is a pressure alteration in chambers "A & B", not by the rate of boost pressure or vacuum in the line. This ensures a quick valve response and complete closure during idle.

Many competitors use a push-type blow-off valve design with a large valve to accommodate high boost / high horsepower applications. These large valves react slowly and require high pressure to open, and are not able to activate and prevent compressor surge at light-load conditions. On the other hand, smaller, fast reacting push-type valves do not discharge the airflow capacity required for high horsepower applications and tend to slowly open and leak as boost pressure overpowers the spring.

For maximum performance, the HKS SSQV incorporates both a small primary valve for ultra quick activation, and a larger secondary valve for additional discharge capacity. The SSQV is engineered to initially open the small primary valve at light throttle and load conditions, then sequentially opens the secondary valve for additional relief capacity under high boost and load conditions.

The SSQV is constructed of polished billet aluminum, which ensures long-term durability and a high luster look. The mounting base utilizes a circular mounting flange that combines with a C-clip snap ring and O-ring gasket to insure an excellent seal. The triple-fin discharge port design produces a powerful, unique and aggressive blow-off sound."

http://www.hksusa.com/products/more.asp?id=792

GReddy Type S and Type RS BOVs
http://www.greddy.com/

"GReddy Blow Off Valves are easily adjustable to prevent both premature boost leakage and compressor surge. Each is made of durable cast and billet aluminum frame and the valve to diaphragm ratio provides performance that cheap piston types cannot offer. The spring stiffness adjustment screw and 3 different sizes give the GReddy user the option to match vehicles with mild upgrades to heavily tuned engines. Also available in an easy to install kit form for many turbocharged vehicles."

Blitz Super Sound BOV
http://www.blitz-na.com/Blitz_Blowoff_DD.htm

"The Blow-off valve is essential to all turbocharged vehicles. The purpose of the BLITZ Blow-off Valve DD is to relieve compressor surge without reducing compressor speed. It controls boost pressure that is built up by the turbo and vents it into the atmosphere when the car is not under load (in between shifts).

This prevents pressure from backing up into the compressor housing, causing the turbo impeller blade to rapidly stop or even worse, to spin backwards (compressor surge or backspin). Doing so can be potentially destructive to the turbine wheel and shaft. Repeated stress over time can cause eminent damage to the turbo charger and eventually lead to turbo failure.

A blowoff valve is actuated by pressure changes only, ensuring quick valve responses and complete closures at idle. The BLITZ blow-off valve not only improves performance and response, but also increases the life of the turbocharger."

TiAL BOV
http://www.tialsport.com/

"For use on turbo-charged and super-charged applications (Paxton, Vortec, etc.). The body and all internal components are CNC-machined from 6061 aluminum alloy. It features a large 1.98 in (50.5mm) valve; we believe this is the largest valve available with the highest flow capacity.

The V-Band design aluminum mounting clamp gives a very clean and unique appearance. The clamp is anodized and uses Stainless Steel hardware for a long lasting, corrosion-free appearance.

The valve seal utilizes a Viton O-ring that is clamped in place to prevent the possibility of sticking to the seat and pulling out. The valve stem and guide are Teflon-lubricated, hard anodize-coated for wear resistance. The Blow Off Valve also comes with our own machined aluminum banjo-type air fitting and bolt, with over sized 10mm hose barb for quick actuator response. The actuator has a high temp silicone Nomex-reinforced diaphragm for long life."

Turbo XS BOVs
http://www.turboxs.com/BOV/bovproducts.shtml

Blow Off Valve Type-S:
The BOV Type S is recommended for small to medium sized turbo charged engines running up to 15 psi boost. Each valve is individually tested to hold 30 lbs. of boost. Sizing of valve is based on flow and not boost pressure.

Blow Off Valve Type-H-RFL:
A new larger billet aluminum body and a beefier piston ensures the valve remains smooth under the most demanding circumstances. This valve relieves compressor pressure surge caused by changing gears or backing off the throttle quickly and is designed for turbo charged engines running up to 25 psi boost.

If you need to ask this valve is too loud for you!

whats the alternatives to BOVs..

A lot of small-frame turbo kits don't include blow-off valves. I believe they do so since there isn't much pressure on the intake side, therefore compressor surge wouldn't be much of an issue. Is it possible to live without one? Perhaps. Personally, since I plan on running greater than 12 psi (someone please hire me!), a BOV would probably be in short order.

I recommend the GReddy Type-S for any application under 18psi. If you want to hear the BOV, here's a link to a vid I shot for my Greddy Turbo Kit.

http://tyrannical.org/philodox1.wmv

Hey Jon, you said you got the Type-S for $139, and the mounting flange for $26, right? Just curious where you ordered them from.

Jeff

Hey Jon, you said you got the Type-S for $139, and the mounting flange for $26, right? Just curious where you ordered them from.

Jeff

Jeff, it was a typo. I got the Type S for $149. Still, it's probably the cheapest you'll be able to find. I bought it from an ebay vendor. Here's the link to his Ebay store.

http://stores.ebay.com/Kuruma-Motoring_W0QQsspagenameZl2QQtZkm

I think I am gonna trust HKS and Greddy Blow offs, maybe go for greddy as thier kit most likely works best with thier blow off valves. Its seem greddy is very smart when it comes to versitility and the upgradadablity of thier kits.

I think I am gonna trust HKS and Greddy Blow offs, maybe go for greddy as thier kit most likely works best with thier blow off valves. Its seem greddy is very smart when it comes to versitility and the upgradadablity of thier kits.

Well, any BOV will work.. A Blow Off Valve just releives built up pressure.. and that pressure doesn't care which BOV you use ;) But since I have the Greddy Turbo Kit, I wanted to keep everything with GReddy.

I had the HKS SS BOV on my FD so I went with the greddy type S and not that is matter the profec e-01 to boot. All greddy so far for performance upgrades.

If the kits use standard flanges you may look at GFB and Worx. Are you guys running 100% Atomosphere or 50/50? The worx bov can be adjusted for both and an adjustment for sound. Just an FYI. :) Congrats on the FI!!!

If the kits use standard flanges you may look at GFB and Worx. Are you guys running 100% Atomosphere or 50/50? The worx bov can be adjusted for both and an adjustment for sound. Just an FYI. :) Congrats on the FI!!!

My Type-S is VTA all the way.

Why do people vent to atmosphere? I always thought that the guys with BOV's making 'da big noise' were just posers.

Isn't it better to route it back into the intake to keep the turbo spooling between shifts?

Or does it not make much difference at all? On my supra my BOV was always venting straight back into the intake.

The turbo won't stop spinning between shifts unless you take an awfully long time. I don't think rerouting it has any benefit in terms of performance as long as your engine management doesn't get confused (depends on location of MAF and whether or not the computer can account for the missing air, which the EManage can...I learn more from these threads every day :) )

There is nothing "poserish" about not taking an extra step to be subtle (like rerouting the BOV vent to the airbox to mute the sound a bit). If you want the living, breathing definition of automotive poser go here. (http://www.takakaira.com/accessories/nightpager/nightpager.html)

The turbo won't stop spinning between shifts unless you take an awfully long time.

Well, if you have no BOV at all, the pressure built up after you let off the throttle bounces off the throttle body and goes back to the turbo itself. That's why when you don't have a blow off valve you hear that "quacking duck" sound. That's the turbo actually despooling and spinning backwards. Then when you get back on the throttle, the turbo needs to do a full blown spool up again. Not to mention that not relieving that backpressure can damage the bearings in the turbo housing itself.

-Jon

i love the hks ss it sounds awesome IMO

i used to have the turboxs BOV on my old talon. loud as hell but probably not the best. they were just very easy to bolt on to the DSM's, mainly just clamped right on to the stock IC piping. they are really easy to control the sound of which mad eit alot of fun to drive around.

but when i go FI on my 8 i will stick with the Greddy BOV. had it on my eclipse and never had a problem with it. VERY reliable equipment from Greddy.

I bought my wife a TurboSmart BOV and was less than happy with it. The tunability of it wasn't really there, unlike the Go Fast Bits BOV I should have bought her. All you could do was loosen or tighten the spring.

The HKS SS sounds like a bird chirp or piece of metal, certainly not what I would prefer my BOV to sound like.

I agree about the blow off valves, though. The only kids I constantly hear with them are the kiddies in their SRT4s, letting you know their wrong wheel drive cars with turbos are near you. Woo.

Hey Jon, a question for you.. I installed the SSQV HKS but i notice no difference in sound compared to before when I had no BOV at all. It sounds weird when I let off the gas.. I dont know how to describe the sound , it is like a horse, like a tu tu tu tu tu, very bad. I recorded a audio clip of ot so you can advice me on this. Is it possible that the BOV is not opening because I am running only 6 psi and the SSQV is designed for higher boost? Hear the clip and let me know please.
If it is like that, i have to go to the HKS dealer and ask him why he reccomended me that BOV knowing I was going to run low psi.

I tried to post the clip but was unable due to "invalid file type", anyone who can help me on this please write ur email and I'll send it to you... Thanks


Well, if you have no BOV at all, the pressure built up after you let off the throttle bounces off the throttle body and goes back to the turbo itself. That's why when you don't have a blow off valve you hear that "quacking duck" sound. That's the turbo actually despooling and spinning backwards. Then when you get back on the throttle, the turbo needs to do a full blown spool up again. Not to mention that not relieving that backpressure can damage the bearings in the turbo housing itself.

-Jon

Hey Jon, a question for you.. I installed the SSQV HKS but i notice no difference in sound compared to before when I had no BOV at all. It sounds weird when I let off the gas.. I dont know how to describe the sound , it is like a horse, like a tu tu tu tu tu, very bad. I recorded a audio clip of ot so you can advice me on this. Is it possible that the BOV is not opening because I am running only 6 psi and the SSQV is designed for higher boost? Hear the clip and let me know please.
If it is like that, i have to go to the HKS dealer and ask him why he reccomended me that BOV knowing I was going to run low psi.

I tried to post the clip but was unable due to "invalid file type", anyone who can help me on this please write ur email and I'll send it to you... Thanks

That my friend is the blow off valve not releasing any pressure at all, hence causing the forced air to bounce off the throttle plate and go towards the turbo. The horse sound (i always say it sounds like a duck) that you hear is the turbo kit despooling very abruptly. This can be bad for the turbo, but only after a few good years of it happening.

I would say that you either 1) didn't connect the vaccume hose to the intake manifold for the BOV, or 2) have the BOV set too tight, looses it up so it takes less vaccume to open it up.

Try either of those things and let me know.

-Jon

Jon,
it should be connected to he intake manifold since it was a shop who did it for me. They have installed many turbos and they are HKS and Greddy dealers. Now, they recomended me the SSQV HKS BOV, it is a beautiful piece but what I dont know is that if that BOV is only for high pressure boost and is not opening at the psi we are running. I read somewhere that they are not adjustable anymore and I tried loosening and tightening he bolt with no improvement at all.
Any ideas? Thanks for your help...


That my friend is the blow off valve not releasing any pressure at all, hence causing the forced air to bounce off the throttle plate and go towards the turbo. The horse sound (i always say it sounds like a duck) that you hear is the turbo kit despooling very abruptly. This can be bad for the turbo, but only after a few good years of it happening.

I would say that you either 1) didn't connect the vaccume hose to the intake manifold for the BOV, or 2) have the BOV set too tight, looses it up so it takes less vaccume to open it up.

Try either of those things and let me know.

-Jon

That my friend is the blow off valve not releasing any pressure at all, hence causing the forced air to bounce off the throttle plate and go towards the turbo. The horse sound (i always say it sounds like a duck) that you hear is the turbo kit despooling very abruptly. This can be bad for the turbo, but only after a few good years of it happening.

I would say that you either 1) didn't connect the vaccume hose to the intake manifold for the BOV, or 2) have the BOV set too tight, looses it up so it takes less vaccume to open it up.

Try either of those things and let me know.

-Jon
Jon, the famous philodox :) I have my type s greddy BOV vacuum hose connected to a t fitting that goes to the greddy boost sensor and vfad port on throttle body. Is that wrong? Should I reroute it to one of the intake barbs on the passenger side of the engine? Also the bottom barb on the bov is left unconnected, right?

thanks

Chris

Okay guys. I have my BOV connected to the manifold port on the drivers side of the engine right next to the throttle body. I am not too familiar with the type of BOV that you're using Lschiavo. I use the Greddy Type-S since it's completly adjustable and good up to 18psi or so. If you're using a BOV that's rated for very high boost applications, then there is a good chance that low boost may keep it from opening properly. If Jeff (Mazdamaniac) is still watching this thread, got any suggestions for these guys?

oh yeah, Chris, doesn't matter much where you have it connected, you'll get a pressure/vaccume from any ports on the intake manifold. I just have mine on the other side since I don't like tubing all over my engine bay :-p

-Jon

Hey guys can u vent to atmosphere??
Is it ok to vent to atmosphere on our engines?

Hey guys can u vent to atmosphere??
Is it ok to vent to atmosphere on our engines?

That's how mine is setup. It's just not a turbo unless that BOV makes the whooosh! sound. hehe.. you'll have no issues with a VTA setup.

Jon,
The BOV is working fine. I tested it disconnecting the hose (recirculator) and it blows the air. I can hear it now while driving. No issues at all by venting to atmosphere. Thanks for your input.
Now, the squeeking duck or horse is still there. I talked to a guy today that seems to know a lot about this and he told me that since I am running the stock pipe and midpipe, the sound is that too much air is getting in the system (with the new intake with the turbo) and it can get out because the pipe that is connected to the manifold (and the rest of the pipe) is not big enough to release all the pressure. As a consequence, the pressure bounces back creating something "I dont remember the term name" something like back pressure or like it and it sounds like that and backfiring too. He told me that the way to get this fixed is getting a bigger pipe all the way to the exhaust pipes. Sounds something logical to you?
As he said, "In other words, too much air in, no enough air out.."

Someone with the same problem?

Thanks


That my friend is the blow off valve not releasing any pressure at all, hence causing the forced air to bounce off the throttle plate and go towards the turbo. The horse sound (i always say it sounds like a duck) that you hear is the turbo kit despooling very abruptly. This can be bad for the turbo, but only after a few good years of it happening.

I would say that you either 1) didn't connect the vaccume hose to the intake manifold for the BOV, or 2) have the BOV set too tight, looses it up so it takes less vaccume to open it up.

Try either of those things and let me know.

-Jon

That sounds about right. Do you have an aftermarket exhaust? I have a borla exhaust with 3" pipe from the cat back. No issues. Maybe there's too much pressure and it's bouncing your exhause gas back to the turbo (bad juju). Keep in mind that a turbo is acutally a restriction on your exhause system, so there may be some logic in it.

I have a racing beat exhaust, but it is not the first part of it (don't know these terms) I have only the back part of it. So the part that is connected to the manifold is stock. I think that will solve the problem. Any ideas on a good one ??
Thanks
Is it 2.5" stock??? What diameter would be good for the turbo??





That sounds about right. Do you have an aftermarket exhaust? I have a borla exhaust with 3" pipe from the cat back. No issues. Maybe there's too much pressure and it's bouncing your exhause gas back to the turbo (bad juju). Keep in mind that a turbo is acutally a restriction on your exhause system, so there may be some logic in it.

Jon,
The BOV is working fine. I tested it disconnecting the hose (recirculator) and it blows the air. I can hear it now while driving. No issues at all by venting to atmosphere. Thanks for your input.
Now, the squeeking duck or horse is still there. I talked to a guy today that seems to know a lot about this and he told me that since I am running the stock pipe and midpipe, the sound is that too much air is getting in the system (with the new intake with the turbo) and it can get out because the pipe that is connected to the manifold (and the rest of the pipe) is not big enough to release all the pressure. As a consequence, the pressure bounces back creating something "I dont remember the term name" something like back pressure or like it and it sounds like that and backfiring too. He told me that the way to get this fixed is getting a bigger pipe all the way to the exhaust pipes. Sounds something logical to you?
As he said, "In other words, too much air in, no enough air out.."

Someone with the same problem?


Thanks
Your theory makes sense, I have the same problem right now and I have the racing beat exhaust with stock cat (my turbo would not run with the sr high flow cat). however, I think there is a "happy medium" using the type s BOV. I had it way to light (loosing boost) and it did not do it at all. i then got it way too tight and now it does it once in a while. I am in the process of lightening the BOV every night after work and testing it out the next day at work. I will keep you up to date with what i find, hopefully we will not have to opt for another new exhaust, my bank account hurts after the turbo still!

Lol, I tried adjusting the bolt on the BOV with no happy results. Mine hurts too but If i dumped almost 7K (Kit+Installation around $1,600 and meters) i am not going to stop for an exhaust even if I have to ask for a loan LOL :D .
Is your sound like a horse??? Does it backfire while idling too????
But hey you know what?? I have that sound even if i am not on boost, even in vacuum if i release the gas I hear it. It is not that loud but stilll in the background i can hear it.
Isn't it horrible?? Sometimes when i let off the gas very easy and gentle it wont do it at all. weird... By the way how much an exhaust cost?? What is the name of the part I need? Thanks


Your theory makes sense, I have the same problem right now and I have the racing beat exhaust with stock cat (my turbo would not run with the sr high flow cat). however, I think there is a "happy medium" using the type s BOV. I had it way to light (loosing boost) and it did not do it at all. i then got it way too tight and now it does it once in a while. I am in the process of lightening the BOV every night after work and testing it out the next day at work. I will keep you up to date with what i find, hopefully we will not have to opt for another new exhaust, my bank account hurts after the turbo still!

yea, i am getting the same sound, mine idles fine, nothing but an occassional pop at idle, no back fires under throttle, just the little ducky sound when i let off the gas, figured out that now it only makes that noise under vacuum and have not been able to get the Bov to adjust it out since there is no boost there under vacuum. Exhausts usually cost around 550 up, i may sell my racing beat and try the greddy one but with the stock cat I can not imagine that it will take care of the problem, but i dunno. Did find a post under the puerto rico turbo thread that said to change the bov to 5/16 to get rid of any sounds under vacuum, i am going to look into that too. I will keep ya posted as to what i find out.

lschiavo, actually it was you that was asking for advice in the puerto rico turbo thread :) lol
Why don't you keep me posted, your doing a better job haha

Where is the best place to have the flange welded onto the intercooler pipe for the Greddy Turbo kit? Is there even a such thing as a better spot for it? I have ordered the Greddy Type RS BOV along with my Turbo kit which should be here in a couple weeks.
Thanks

btw...Please forgive me if I missed this info in my reading. If it has already been answered, simply tell me so and I will look harder!

TurboXS is CRAP. I've had two Greddy Type S bov's. Both have leaked after a year or so. But it was an easy fix. Tials are too big for yous guys application. Also Greddy/Trust doesn't make the type s anymore either. So if you guys see some on ebay make sure they are not "Greddy STYLE".

As far as adjusting the type s, I was able to hold 10-20psi with the screw adjusted halfway out of the bov and then the tighting nut was put on. So crank that screw all the way down and then back it out a little more then half way and go from there.

Thanks GTAW, I appreciate the info! This just goes to prove that one becomes smarter by associateing with those smarter then them!

Regards,
Sillybastard :beer05: