HKS BOV not "blowing"

[joe645733]

hey what's going on.

recently purchased a 1jz sc300 which is putting out 560whp.

i'm putting out roughly 26psi on WOT and i have a vacuum of...i want to say -20 inches at idle?

the HKS BOV never goes off and i am getting some surge on my brand new borg warner S363 turbo. reason i replaced the turbo was because of an oil leak from inside of the turbo. currently rebuilding the turbo. i believe this particular BOV is not adjustable, but is it possible the internals can just be seized/locked up?

anyways, because it's a brand new turbo, i'd like to address the issue to extend the longevity of this fresh turbo.

thanks, guys/gals

[KAT-PWR]

...Do you have it connected properly?

[fatduece]

Thats not surge.

[Frank_Jaeger]

The flutter you're hearing is good for you and your turbo. BOVs are for making noise only.

[derass]

Is it real? There are a lot of fake ones out there, one of which came on a car I bought. It was crap, didn't work either. I changed it for a TiAL.

[joe645733]

appreciate the responses.

I bought the car as is, for the most part. As far as I can see, the hoses are hooked up accordingly. The car was tuned by megasquirt, from someone named, Jordan, who seems to be a reputable tuner. I'm assuming he would have looked or noticed something like that, but I understand people make mistakes.
Is it possible that a BOV can just be bad?

I know 100% the sound of an HKS BOV, as it makes that "chirp" sound, which personally I'm not a fan of, but aside from that, I haven't heard it once out of the month that I've owned the car. I know for a fact the sound I hear after full throttle is from the turbo. It's pretty noticeable.
I'll be goofy via text, but the turbo makes a pretty harsh "BEW BEW" noise after heavy acceleration, haha

[joe645733]

Just wish it were something where I can check with a multimeter or something. Which is why I'm asking you guys: is it possible that a BOV can just be bad? Cuz I can just replace it, as it's pretty cheap. Just wanted to confirm some opinions from others.

Thanks

[jr_ss]

I'm assuming it's an SSQV? You haven't really given any details other than it being an HKS BOV and it makes a chirp.

If it's an SSQV, it needs to see pressure change to function properly. Hook up the vac hose as close to the throttle body as possible.

[joe645733]

The flutter you're hearing is good for you and your turbo. BOVs are for making noise only.

You know what, I figured BOVs were completely useless

[Kingtal0n]

You know what, I figured BOVs were completely useless

they arn't he was trolling you. Dont believe anything anyone says on this site unless you have done your own research.

While that horrible noise you hear is happening, the shaft is being slamming into the CHRA as the wheel tries to rip free of it's housing. The tiny clearances set by the turbo manufacturer are taken up by that sight movement (that gradually becomes more and more as you keep doing this) and bit and pieces of your wheels will start to contact the housing and turn to dust, the edges of your wheel will start to look like shredded cheese. Even with no contact, the force of air molecules is enough to damage the tips of the wheel, as they get an 'ultra sonic cleaning' (high pressure fast moving air molecules squeezing between tight space in the reverse direction they are intended to flow will gradually weaken/bend/disintegrate the tips of the compressor wheel)

You need a properly functioning bypass valve if you expect the turbo to live a long life.

[KAT-PWR]

"But drifters in japan where oem turbos are close to free don't run bov's"
....Think about it
Save the turbos.
No BOV will put your turbo in a box like houdini.

[bansheeracer2003]

they arn't he was trolling you. Dont believe anything anyone says on this site unless you have done your own research.

While that horrible noise you hear is happening, the shaft is being slamming into the CHRA as the wheel tries to rip free of it's housing. The tiny clearances set by the turbo manufacturer are taken up by that sight movement (that gradually becomes more and more as you keep doing this) and bit and pieces of your wheels will start to contact the housing and turn to dust, the edges of your wheel will start to look like shredded cheese. Even with no contact, the force of air molecules is enough to damage the tips of the wheel, as they get an 'ultra sonic cleaning' (high pressure fast moving air molecules squeezing between tight space in the reverse direction they are intended to flow will gradually weaken/bend/disintegrate the tips of the compressor wheel)

You need a properly functioning bypass valve if you expect the turbo to live a long life.

^This is Correct
OK this might sound weird but it worked for me
Try sparying some wd40 in the bov and the line that goes into it
and if it starts working a little bit then your valve is probably bad
it loosed mine up and made it work but i was never perfect.

[spools420a]

take it apart and see if diaphragm tore or if vacuum line is broke going into bov

[joe645733]

they arn't he was trolling you. Dont believe anything anyone says on this site unless you have done your own research.

While that horrible noise you hear is happening, the shaft is being slamming into the CHRA as the wheel tries to rip free of it's housing. The tiny clearances set by the turbo manufacturer are taken up by that sight movement (that gradually becomes more and more as you keep doing this) and bit and pieces of your wheels will start to contact the housing and turn to dust, the edges of your wheel will start to look like shredded cheese. Even with no contact, the force of air molecules is enough to damage the tips of the wheel, as they get an 'ultra sonic cleaning' (high pressure fast moving air molecules squeezing between tight space in the reverse direction they are intended to flow will gradually weaken/bend/disintegrate the tips of the compressor wheel)

You need a properly functioning bypass valve if you expect the turbo to live a long life.


Yeah, dude, I was just playing around, hah.

[joe645733]

Thanks for the responses, everyone, minus the tool, Frank.

This isn't my first turbo car, but I never did put in research with what I'm dealing with. The car is new to me and was mainly just wondering if a BOV can just simply break, internally.

But again, thanks and look into it later today

[joe645733]

they arn't he was trolling you. Dont believe anything anyone says on this site unless you have done your own research.

While that horrible noise you hear is happening, the shaft is being slamming into the CHRA as the wheel tries to rip free of it's housing. The tiny clearances set by the turbo manufacturer are taken up by that sight movement (that gradually becomes more and more as you keep doing this) and bit and pieces of your wheels will start to contact the housing and turn to dust, the edges of your wheel will start to look like shredded cheese. Even with no contact, the force of air molecules is enough to damage the tips of the wheel, as they get an 'ultra sonic cleaning' (high pressure fast moving air molecules squeezing between tight space in the reverse direction they are intended to flow will gradually weaken/bend/disintegrate the tips of the compressor wheel)

You need a properly functioning bypass valve if you expect the turbo to live a long life.

Thanks for explaining

[Croustibat]

Thanks for the responses, everyone, minus the tool, Frank.

This isn't my first turbo car, but I never did put in research with what I'm dealing with. The car is new to me and was mainly just wondering if a BOV can just simply break, internally.

But again, thanks and look into it later today

I'd say 90% second hand HKS SSQV bovs are fake, so chances are, yours too.

Even then, they are mechanical items so they can wear.

[joe645733]

Okay so I took that part of the intercooler piping apart with the BOV flanged.

As far as seeing if it's fake, it does say HKS imprinted on the top of it, the back has an engraving, and the front where if pushes in and out says sequential blow off valve. Now, I don't know how indepth knockoffs get to making their fake products look new, but it seems legit? The flange also had a serial/part number on it.
So first thing I did was put negative pressure to where the hose hooks up, and no air passed through, which id imagine is good.

Then in the front, I pushed the disc, (or whatever it's called), in, and I did feel like it was stuck. So I pushed it in and out to exercise it a bit.
Took apart all the little nuts/bolts, which then revealed the diaphram and spring. No tears on it. Cleaned it up a bit and threw some WD40 in the front of the valve, where I found it stuck.

Assembled everything back together and under boost I'm still not hearing it...the BOV is mounted roughly 2ft from the throttle body.

Still possible it can just be bad? I'm not sure if there's more parts to pay attention to in the valve?

Side note- at idle I'm at -30" and under boost I'm at 27psi.

Car is an e85 tune and running a fresh new turbo.
About you guys saying I'm affecting the longevity of the turbo, (which I'm aware of), what length in time are we talking about with premature failure?

We talking within say, a matter of week(s) I can ruin the turbo?

Thanks!

[joe645733]

How the hose diagram goes:
Out of the manifold, there a hose that splits to a T. One of the hoses goes directly to the external wastegate and the other goes right to the BOV. I've verified there's no leaks

[Kingtal0n]

Okay so I took that part of the intercooler piping apart with the BOV flanged.

As far as seeing if it's fake, it does say HKS imprinted on the top of it, the back has an engraving, and the front where if pushes in and out says sequential blow off valve. Now, I don't know how indepth knockoffs get to making their fake products look new, but it seems legit? The flange also had a serial/part number on it.
So first thing I did was put negative pressure to where the hose hooks up, and no air passed through, which id imagine is good.

Then in the front, I pushed the disc, (or whatever it's called), in, and I did feel like it was stuck. So I pushed it in and out to exercise it a bit.
Took apart all the little nuts/bolts, which then revealed the diaphram and spring. No tears on it. Cleaned it up a bit and threw some WD40 in the front of the valve, where I found it stuck.

Assembled everything back together and under boost I'm still not hearing it...the BOV is mounted roughly 2ft from the throttle body.

Still possible it can just be bad? I'm not sure if there's more parts to pay attention to in the valve?

Side note- at idle I'm at -30" and under boost I'm at 27psi.

Car is an e85 tune and running a fresh new turbo.
About you guys saying I'm affecting the longevity of the turbo, (which I'm aware of), what length in time are we talking about with premature failure?

We talking within say, a matter of week(s) I can ruin the turbo?

Thanks!

okay. first of all the HKS bypass barely qualifies as a bypass. By this I mean it barely gets the job done in small horsepower applications i.e. 300 horsepower and less. For anything 400+ you want a real bypass, a fancy tial or an HKS race or something.

Second of all, no bypass is going to work great on the cold side (near the throttle body). Think about the mass of air in the intercooler that needs to evacuate before any kind of pressure drop can be detected in the hot-pipe, by which time it is too late. Your effort trying to run the tiny HKS bypass on the wrong side is futile. It will never give your turbo the relief it needs under all situations.

Many turbo manufacturers are now integrating a bypass on the compressor itself- the proper location. They need to be as close to the compressor as possible.

Here is an example from my car
http://i9.photobucket.com/albums/a90/kingtal0n/Kingtal0ns_240sx_2/HOTPIPE/P1250932_zpshjekbruu.jpg (http://s9.photobucket.com/user/kingtal0n/media/Kingtal0ns_240sx_2/HOTPIPE/P1250932_zpshjekbruu.jpg.html)

[joe645733]

okay. first of all the HKS bypass barely qualifies as a bypass. By this I mean it barely gets the job done in small horsepower applications i.e. 300 horsepower and less. For anything 400+ you want a real bypass, a fancy tial or an HKS race or something.

Second of all, no bypass is going to work great on the cold side (near the throttle body). Think about the mass of air in the intercooler that needs to evacuate before any kind of pressure drop can be detected in the hot-pipe, by which time it is too late. Your effort trying to run the tiny HKS bypass on the wrong side is futile. It will never give your turbo the relief it needs under all situations.

Many turbo manufacturers are now integrating a bypass on the compressor itself- the proper location. They need to be as close to the compressor as possible.

bought the car as is. but thanks for your help.

and it sucks there's so much different advise out there. for example, most posts i see say the BOV needs to be close to the throttle body.

so you're saying i should have the BOV as close to the compressor, in that case, close to the external wastegate? i'm surprised the MegaSquirt shop didn't know this.

and i am currently in the 570whp region
it's weird - a lot of the people with my platform seem to have them WELDED to the throttle body, hah

[R3b]

Its all a matter of preference where the bov sits. Im not a jdm tuning god but it shouldn't really matter which pipe your bov is on.

Another thing is how did you get a hold of the 560 something hp car?? There is no way thats some craiglist find and you shelled out 10k plus unless you have loads saved up.

I got my hatch with a ka-t and the previous owner used cheapish parts mainly a china charger turbo, going to replace that soon with this new PT I have laying around and this knockoff hks. For me mine stays open at idle but it doesnt affect me much since im on a blow through setup, and the other thing was when I got on it I never herd the typical PSHHHH sound when you rev on idle which for some reason some engines can or cant make unless your two stepping, never understood that about bov's and I never really got the sound when I was in actual boost. So I ended up taking it apart and it ended up having a stick between the diaphragm.

If it wasn't for my blow through setup the car would have had a massive leak. The next thing is I put it back together cleaned it up and it was finally working, still open idle. So I took it apart again and put a washer to push to spring and diaphragm more forward I think my vac is -25 to -27. Still open on idle... took it apart again and stretched it a bit. Still open on idle, I just said fuck it and left it. Now when im driving normal I hear the very typical pshhhh noise but very long and obnoxious but when I get on it then I get the normal flutter noise from the bov. Ironically im only running around 5psi of boost since im babying the motor till a rebuild so I dont think I could have surge on such low boost.

Thats my experience with hks knockoff bov. They arent really bad but for you since your in high HP range i'd get the race version or get a tail with another spring. If you get the chance to get on a dyno ask a buddy to look at your bov or turbo. Maybe the flutter noise you are hearing is the bov which opens and closes really fast getting the TUtutu sound and not the long PSHHH.

[joe645733]

Its all a matter of preference where the bov sits. Im not a jdm tuning god but it shouldn't really matter which pipe your bov is on.

Another thing is how did you get a hold of the 560 something hp car?? There is no way thats some craiglist find and you shelled out 10k plus unless you have loads saved up.

I got my hatch with a ka-t and the previous owner used cheapish parts mainly a china charger turbo, going to replace that soon with this new PT I have laying around and this knockoff hks. For me mine stays open at idle but it doesnt affect me much since im on a blow through setup, and the other thing was when I got on it I never herd the typical PSHHHH sound when you rev on idle which for some reason some engines can or cant make unless your two stepping, never understood that about bov's and I never really got the sound when I was in actual boost. So I ended up taking it apart and it ended up having a stick between the diaphragm.

If it wasn't for my blow through setup the car would have had a massive leak. The next thing is I put it back together cleaned it up and it was finally working, still open idle. So I took it apart again and put a washer to push to spring and diaphragm more forward I think my vac is -25 to -27. Still open on idle... took it apart again and stretched it a bit. Still open on idle, I just said fuck it and left it. Now when im driving normal I hear the very typical pshhhh noise but very long and obnoxious but when I get on it then I get the normal flutter noise from the bov. Ironically im only running around 5psi of boost since im babying the motor till a rebuild so I dont think I could have surge on such low boost.

Thats my experience with hks knockoff bov. They arent really bad but for you since your in high HP range i'd get the race version or get a tail with another spring. If you get the chance to get on a dyno ask a buddy to look at your bov or turbo. Maybe the flutter noise you are hearing is the bov which opens and closes really fast getting the TUtutu sound and not the long PSHHH.

money, i guess, hah.

and disregard all of this...i'm facing another issue.

i found a 2nd BOV in the intercooler piping circuit...it's a tial BOV that i found burried in the engine bay.

my apologies; again, this is a new car i bought from someone who wasn't sure what was done to the car, himself. he bought the car as-is, as well.

i'll take the tial BOV apart tomorrow and see what's going on.

what a twist to this awesome story

[jr_ss]

I think my vac is -25 to -27.

No, it's not. Your means of reading this is wrong. Fix your gauge or buy a quality one. 22-23" is the highest you should see on a healthy motor at idle.

Side note- at idle I'm at -30".

As stated above, it's not possible. Please check, fix and/or replace your gauge or means of reading that data point.

[R3b]

I dont drive the car everyday but my vac is pretty high, maybe I over exaggerated a bit but its at least 20-25. Motor isnt really the healthiest so thats why im babying till I go nuts with a rebuild. One day is just randomly started missing and checked my full rail and 1st and 2nd injector just would open up. Replaced them and car is running amazing, had other issues with idle and afrs but was small stuff because the last owner didnt know what he was doing. Compression is 140-155-160-150, the first cylinder is a bit concerning but recently. Luckily I dont drive it much, maybe only 250 miles so a tank and a bit since im on corn. Maybe the rings are finished from the first injector not spraying nicely and leaning out. When I got the car I herd a small tiny little miss but got better after redoing the idle and timing.

[R3b]

i found a 2nd BOV in the intercooler piping circuit...it's a tial BOV that i found burried in the engine bay.

i'll take the tial BOV apart tomorrow and see what's going on.

what a twist to this awesome story

Where exactly was it, kinda strange for it to have two? Exspecially since the hks seems to be a knockoff?

Does the tial have any hoses to it? Tials work a bit differently but there easy to take apart, maybe you could get a flange plate for the hks and just run the tial, it should hold up fine with a new spring.

[Frank_Jaeger]

money, i guess, hah.

and disregard all of this...i'm facing another issue.

i found a 2nd BOV in the intercooler piping circuit...it's a tial BOV that i found burried in the engine bay.

my apologies; again, this is a new car i bought from someone who wasn't sure what was done to the car, himself. he bought the car as-is, as well.

i'll take the tial BOV apart tomorrow and see what's going on.

what a twist to this awesome story
There's your problem. You have two BOVs when you should have none.

[Kingtal0n]

Whatever you wind up doing, pressure the system when its done to 15 or 20psi. The engine from Throttle body to compressor wheel should hold that pressure for a few moments.

[joe645733]

There's your problem. You have two BOVs when you should have none.

Yeah but what if I bought a third

[Croustibat]

Car is an e85 tune and running a fresh new turbo.
About you guys saying I'm affecting the longevity of the turbo, (which I'm aware of), what length in time are we talking about with premature failure?

We talking within say, a matter of week(s) I can ruin the turbo?

Thanks!

27psi without a bov may be a bit too much, 10-15 is kind of ok.
You won't ruin your turbo in a matter of weeks bacause of a lack of blow off valve. It may take some days/ weeks off its life, but if it is not a chinabay special, its life can be counted in years.


[...]and it sucks there's so much different advise out there. for example, most posts i see say the BOV needs to be close to the throttle body.

so you're saying i should have the BOV as close to the compressor, in that case, close to the external wastegate? i'm surprised the MegaSquirt shop didn't know this.[...]


Free information dictated by "common sense" and posted on zilvia ... What could go wrong really ? Don't hold your breath too much. You need to realize businesses rely on their information being correct AND no common knowledge to work. They don't give that information away, because they may as well close their business. Meaning your only source of information is the people who actually aren't in the know, so take free informations with a pinch of salt. I doubt anyone answering the BOV position can of worm is actually working in R&D in that domain.

Anyway the megasquirt shop as you call it makes tunes. They don't need to know where to place a BOV, or if it matters.

[RB25GUY]

^ correct anything under 20 psi with any reputable turbo you will be fine i called COMP TURBOS about running a 5562 TBB without a BOV he said it was fine unless you plan on running more than 20 psi but he did suggest on the bigger turbos to run a BOV

[joe645733]

Alright so after investigating the second BOV, I removed it and it's most likely a knockoff (from Tial). Opened it up and didn't see anything visually bad, but the spring inside is super tight. As soon as I found this out, I did order a real Tial 50mm BOV.

So I did some research online and some people cut the spring to loosen some tension. So I did this just for the hell of it until my BOV comes in.
So after cutting, under boost, I'm finally hearing it open up and make noise. My question is...why am I hearing the BOV slightly delayed AFTER my surge from the turbo? Still too tight of a spring? And I was only giving it maybe 5psi from the turbo.

Thanks, guys

[Kingtal0n]

Alright so after investigating the second BOV, I removed it and it's most likely a knockoff (from Tial). Opened it up and didn't see anything visually bad, but the spring inside is super tight. As soon as I found this out, I did order a real Tial 50mm BOV.

So I did some research online and some people cut the spring to loosen some tension. So I did this just for the hell of it until my BOV comes in.
So after cutting, under boost, I'm finally hearing it open up and make noise. My question is...why am I hearing the BOV slightly delayed AFTER my surge from the turbo? Still too tight of a spring? And I was only giving it maybe 5psi from the turbo.

Thanks, guys

This is a common problem when placement is too far. move the bov closer to the compressor and the pressure drop created by it will "get there quicker". Again think of my example of the bypass on the cold side- you have to empty the intercooler volume as you empty the hot-pipe. Any pressure drop that registers in the hotpipe will also have to be recorded in the cold pipe and intercooler.

Other things that may improve response:
Make the bypass easier to open (adjustments to spring/diaphragm)
Increase vacuum signal (use large vacuum line, sole dedication to the bypass, short as possible)

I go through this debate constantly and have provided 10 examples over the years. Another example would be:
Imagine your hot pipe length was adjustable and that there was no intercooler or cold side at all. Please the bypass as far away as possible from the compressor- 20 feet away for example. Now fill the plumbing with 10psi of air pressure, and open the bypass and measure how long it takes to empty the tube. Now repeat the test with the bypass 30 feet away, then 40 feet away, then 50 feet away, 1000, 50000, infinity. As the length of the tube approaches infinity, the difference in pressure drop per unit time (change in pressure per millisecond is how we measure response) approaches zero, in other words, there is no relief whatsoever when opening the bypass since there is an infinite amount of air to evacuate. You therefore see the important of keeping volume as far from infinity as possible, that is, as close to zero (as short and small of a bypass tube connecting the compressors outlet with the bypass as possible while still meeting minimum size requirement for anticipated flow).

To put this another way, as you increase the distance from the compressor, and increase the air volume that needs to be evacuated by the bypass, the result is that it takes longer and longer to empty the plumbing, which means the pressure remains elevated for longer and longer periods of time (while it is elevated, it is causing surge condition) Whereas, if you install the bypass directly on the compressor the response is instantaneous, since it doesnt need to empty gallons of air volume from the plumbing. Indeed many manufacturers are installing their bypass directly on the compressor these days. The running engine helps evacuate what is left in the remaining plumbing, but if we consider the entire packaging together then it would also make sense to have a bypass on the cold side as well. This isn't done normally since the cost and additional complications (another place for something to leak or break, etc...) and that many systems do not need an extra bypass. I throw this out there only to make it clear what I am suggesting- that the first place I would put the bypass is on the compressor and then close to it as possible. For sure. Absolutely if possible. And then if I exhausted all the different styles and designs of bypass available within my budget (for example, if this is a budget application without access to any brand new parts) there is a niche category of cars that fit the bill for this double bypass situation no doubt. I myself run twin bypass valves on my budget street application, because it just happened that way I never planned it to be that way and it works magically, and this is not my first car with twins, so I am all for additional bypass complexity and fancy recirculate tubes if the fates have steered you there by coincidence. You should be able to get twin ill-placed bypass valves to work as effectively as one single well placed bypass.

[joe645733]

This is a common problem when placement is too far. move the bov closer to the compressor and the pressure drop created by it will "get there quicker". Again think of my example of the bypass on the cold side- you have to empty the intercooler volume as you empty the hot-pipe. Any pressure drop that registers in the hotpipe will also have to be recorded in the cold pipe and intercooler.

Other things that may improve response:
Make the bypass easier to open (adjustments to spring/diaphragm)
Increase vacuum signal (use large vacuum line, sole dedication to the bypass, short as possible)

I go through this debate constantly and have provided 10 examples over the years. Another example would be:
Imagine your hot pipe length was adjustable and that there was no intercooler or cold side at all. Please the bypass as far away as possible from the compressor- 20 feet away for example. Now fill the plumbing with 10psi of air pressure, and open the bypass and measure how long it takes to empty the tube. Now repeat the test with the bypass 30 feet away, then 40 feet away, then 50 feet away, 1000, 50000, infinity. As the length of the tube approaches infinity, the difference in pressure drop per unit time (change in pressure per millisecond is how we measure response) approaches zero, in other words, there is no relief whatsoever when opening the bypass since there is an infinite amount of air to evacuate. You therefore see the important of keeping volume as far from infinity as possible, that is, as close to zero (as short and small of a bypass tube connecting the compressors outlet with the bypass as possible while still meeting minimum size requirement for anticipated flow).

To put this another way, as you increase the distance from the compressor, and increase the air volume that needs to be evacuated by the bypass, the result is that it takes longer and longer to empty the plumbing, which means the pressure remains elevated for longer and longer periods of time (while it is elevated, it is causing surge condition) Whereas, if you install the bypass directly on the compressor the response is instantaneous, since it doesnt need to empty gallons of air volume from the plumbing. Indeed many manufacturers are installing their bypass directly on the compressor these days. The running engine helps evacuate what is left in the remaining plumbing, but if we consider the entire packaging together then it would also make sense to have a bypass on the cold side as well. This isn't done normally since the cost and additional complications (another place for something to leak or break, etc...) and that many systems do not need an extra bypass. I throw this out there only to make it clear what I am suggesting- that the first place I would put the bypass is on the compressor and then close to it as possible. For sure. Absolutely if possible. And then if I exhausted all the different styles and designs of bypass available within my budget (for example, if this is a budget application without access to any brand new parts) there is a niche category of cars that fit the bill for this double bypass situation no doubt. I myself run twin bypass valves on my budget street application, because it just happened that way I never planned it to be that way and it works magically, and this is not my first car with twins, so I am all for additional bypass complexity and fancy recirculate tubes if the fates have steered you there by coincidence. You should be able to get twin ill-placed bypass valves to work as effectively as one single well placed bypass.


Your first couple parts is what I needed. I understand the further it is, the greater the pressure drop will occur.
Appreciate it.
This knockoff BOV is actually before the intercooler, roughly 2ft away from the compressor side of the turbo.
I've cut the spring in two parts and I'm almost getting there.

BUT, what's too easy of a tension spring? I'm cutting increments of maybe a half inch at a time. But again, I did get it making some noise.

Thanks again, dude.

[R3b]

The tail springs are based on vacuum pressure, make sure you get the right one because if you get too light of a one it will be a massive leak and too heavy it wont open nicely.

[Kingtal0n]

So this is how the adjustment goes. Ideally, a bypass will hang open at idle. The one on my hotpipe in the picture on page 1 of this thread hangs open all the time at idle. So I have the spring setting adjusted fully loose. This is how the OEM bypass operates, and this is what you want on a MAF car. Allowing the bypass to recirculate at all idle will minimize noise at the maf sensor. The maf is very sensitive to the incoming air, and if the bypass shuts as the engine returns to idle, the compressor wheel's mild surge behavior will be detected at the maf sensor, even if you cannot hear it (I can hear it easily because I run OEM exhaust but many do not). In other words, to keep the incoming air signal to noise ratio consistent at the maf sensor, you want the bypass to open very easily under all situations and stay open- except wide open throttle of course. Too loose of a spring/diaphragm and it may leak under boost situations. So there is a borderline between a weak setting that allows the bypass to open easily- and stiff enough to hold boost pressure.

If the bypass is not recirculated, then you cannot run an open bypass at idle. The only time you can allow it to open is when RPM > 1400 and TPS voltage < 0.5v~
In other words, above idle, full throttle lift situations. This is when the ECU pulls 100% fuel (complete fuel cut) so it is safe to blow up the maf signal with an atmospheric bypass. This is what the HKS SSQV shines at doing- it generally mixes very well with MAF engines because of it's inherent characteristic of only opening during this scenario.

[R3b]

Or you can run a blow through setup with the maf or go towards map tuning so you dont have to worry about leaks and recirculating 24/7 like a normal maf setup. Just my .02, I love my blow through ka-t, could basically run with no bov, turbo or even a blown coupler. There is downsides but im loving it.

[fatduece]

bovs are for suckers