$0.16 BOV mod

[SeeeeeYa]

Originally Posted by Rescuer

is it OK to drill the hole on the back side?

Someone needs to rescue you from doing this.

Read the thread. You don't know what's happening and are going to ruin something until you know how this works.

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[Rescuer]

i read it once before, but still learning so there is confusion factor.
read whole thread a 2nd time, am feeling more confident about it. will do this mod and drill the hole where it should go along that spine part.
thanks

i've also checked out your bullet TMIC mod which seems very very interesting.

[SeeeeeYa]

Originally Posted by Rescuer

i read it once before, but still learning so there is confusion factor.
read whole thread a 2nd time, am feeling more confident about it. will do this mod and drill the hole where it should go along that spine part.
thanks

i've also checked out your bullet TMIC mod which seems very very interesting.

It's good you took that the right way, more than one have ruined theirs by drilling in the wrong place, or by drilling too far into that "spine," as you call it. What is to be drilled through is an internal tube... and the hole is to be drilled carefully just far enough to enter the outside wall of that tube. That inner tube is an air channel between the bottom of the valve and the top of the diaphragm. After the plug is installed into the end at the bottom of the valve, the little hole that's drilled reopens that tube to atmospheric. The little felt piece over it lets it breathe but protects against entry of foreign matter.

And in response to the question earlier asked about why it wasn't done this way in the first place... It is, in a JDM model, but with a slightly softer spring. The ideal option for an STi is, arguably, the JDM part, if cost is no object. Personally, I think it becomes perfect after this mod.

Thanks for the comment about the BP Mod. You can find more info here.

[isotopesope]

I just did this mod today for $0.00 at work, before heading home. Right away I noticed a better response and enjoyed the lack of hypersensitivity of the bpv from subtle throttle changes. Seems nicer, in the brief driving I have done with it, but it REALLY changed the sounds more than I was anticipating. Also, is it normal to sound so fluttery at lower boost shifts? Its sounds mean at full boost, but is a short stutter sound at mid boost shifts, and super fluttery at lower boost. This is on my 08 wrx, with a Cobb SF intake and a OTS stage one map.

I did this mod in hopes of alleviating a subtle off throttle deceleration boost leak I have been noticing. I don't hear it when I put the stock airbox back on. It is illustrated quite well here:
http://forums.nasioc.com/forums/show...6&postcount=61

A few folks with this sound fixed it by buying an aftermarket bpv or bov. I was hoping this would fix my problem, but I am still hearing it, though now at a higher rpm.

Thoughts?

[isotopesope]

so after rereading this thread yet again, i have noticed others describing a fluttering. is this the surge folks are talking about? i am only hearing it during shifts or letting up on the throttle. it is not happening while under boost.

also, what is the consensus on the drilled vent hole? i used a 1/16" (.0625) jobbers drill, and glued a piece of felt like material over it... though others are saying they used a 3mm (.118") and other are saying they used the drill that came with their 1/4-20 tap, which is probably a #7 drill (.201") that is a huge variance in sizes! would using a difference size vent hole essentially "tune" this mod to work differently?

[SeeeeeYa]

Originally Posted by isotopesope

so after rereading this thread yet again, i have noticed others describing a fluttering. is this the surge folks are talking about? i am only hearing it during shifts or letting up on the throttle. it is not happening while under boost.

also, what is the consensus on the drilled vent hole? i used a 1/16" (.0625) jobbers drill, and glued a piece of felt like material over it... though others are saying they used a 3mm (.118") and other are saying they used the drill that came with their 1/4-20 tap, which is probably a #7 drill (.201") that is a huge variance in sizes! would using a difference size vent hole essentially "tune" this mod to work differently?

That's my theory, and it works for me. YMMV

http://forums.nasioc.com/forums/show...&postcount=256

[isotopesope]

cool, we'll i am going to stick with the 1/16 hole.

so is that fluttering i am getting the "mini-surge" you think is beneficial? and thus a symptom of why it does "feel" better to drive? the drastic change in noises was unexpected.

i appreciate your theories and experience on this mod, and also am going to make your bulletproof mod myself, whenever i get some time and a turbo blanket and install this DP i've had laying around for way too long.

[SeeeeeYa]

Originally Posted by isotopesope

cool, we'll i am going to stick with the 1/16 hole.

so is that fluttering i am getting the "mini-surge" you think is beneficial? and thus a symptom of why it does "feel" better to drive? the drastic change in noises was unexpected.

i appreciate your theories and experience on this mod, and also am going to make your bulletproof mod myself, whenever i get some time and a turbo blanket and install this DP i've had laying around for way too long.

I wouldn't call it beneficial, it just isn't detrimental. It is, however, as you say, an accompaniment of the change that feels good to drive. I don't hear it myself, my AEM CAI is down in a sealed fenderwell. The reason you hear it is because your intake magnifies ALL intake sounds. I only hear my BPV vent during higher-boost shifts, and it's not all that loud even then.

Your car will like the mods you mention. You will have more power, less heatsoak, and a far more reliable vehicle.

[ride5000]

Originally Posted by isotopesope

that is a huge variance in sizes! would using a difference size vent hole essentially "tune" this mod to work differently?

there is no appreciable airflow through this hole, only a reference pressure.

so, no.

[isotopesope]

Originally Posted by ride5000

there is no appreciable airflow through this hole, only a reference pressure.

so, no.

cool, thanks. after re-re-re-re-reading this thread, i did come across some references to that. i honestly am finally beginning to grasp the how's and why's of how this mod works. this is my first turbo car and i have a pretty sophomoric understanding how the turbo system works in general.

this fluttery business still weirds me out and is pretty bad at low to mid boost shifts or throttle lifts. i noticed seeeeya's comment:
http://forums.nasioc.com/forums/show...&postcount=191

Originally Posted by SeeeeeYa

Now that I've gotten my WGDC tables to account for the modded BPV I have quicker spool and more power, all from the same 22.5psi I've always chosen. I may change that now .

The light compressor surge I initially got with a quick throttle lift has largely disappeared after tuning my WGDC, AND learning to drive without snapping the throttle shut.

while i still have yet to log anything since the mod, i feel too green to dare start tweaking with my tune myself, but i also think my driving habits are also coming into play too, in terms of trying to not "snap the throttle shut." though sometimes even rolling off the throttle is giving me flutter.

AND i still have that weird squeaky noise, which was the entire reason i did this mod. others with my same noise said the stock bpv was the culprit and went away with an aftermarket one. i just want to get these issues resolved before installing my DP and etc.

[gordon75]

I have see people crush the cap but does not always work

[mechatricity]

I did this yesterday just for the heck of it. I'm running a Td04 @ 18PSI so i'll likely revert back until i have i have reason to believe the BPV can no longer hold my boost pressure (getting EBCS + retune next week), as the surge is loud and consistent at any boost level.

I spent 30 minutes driving around town giggling like a school girl.

http://youtu.be/g5WvHL-nTRM

[isotopesope]

well, my faithful DIY'ers, i've caved in for the bling. C.R.E.A.M. the fluttering was too disconcerting for me, so i reverted my bpv. i then recently bought a forge recirculating one. i installed it last night; it seems to be the happy medium between less hypersensitivity and MUCH less fluttering. i get a tiny bit running the yellow spring, but it's very slight and not often at all. it also cured that annoying squeak i was getting, which is the "hole" reason i tried this mod in the first place.

as a side note, i drilled out my .062" vent hole with a #7 drill, tapped it, then installed a super short 1/4-20 set screw to plug it... i also took a second super short set screw and drilled a .062" hole through it, so i could swap back and forth between stock and modded functionality easily, and also allowing me to experiment with various vent hole sizes, depending on my set screws. i installed a DP, tried the modded function again, but still was not into it, and went back to stock.

cliffs notes: blah blah blah blah blah

[SeeeeeYa]

I think some of the differing experiences of people who do this mod is the direct result of their driving... and a lack of understanding of how the characteristics of the modded BPV map onto that driving experience.

For example; knowing that their system will now maintain a boost level once developed (say 6-8ish psi), instead of always operating from square one, HOW one manipulates requested torque (mashes the pedal) changes relative to the same car without the mod. Drive without making boost and not much changes. But drive at a more moderate level that involves making a little boost and your pedal use and shifting changes. With the mod, you can make use of that resident boost by shifting smoothly and keeping torque requirements evenly flowing to provide a more muscular, but moderate, acceleration experience.

But ask for torque that involves the same boost, and all you wanted was that one moment of pedal experience so you drop back to where you should have been in the first place... and you get "flutter." It's telling you you didn't work the machine right. Like sticking a sharp stick in its ribs makes it grunt, instead of tapping it on the flank to let it know you want more forward motion.

If you drive to HEAR the BPV vent, you are likely abusing the car by driving amateurishly, and on a graph your requested torque inputs would be a sawtooth. The throttle is your voice, commanding action. Not a request for audience participation.

If you don't consider the changed machine the modded BPV enables, and ask for torque in an incorrect gear, you will push your turbo past its surge line, and get flutter. Again, uneducated pedal use. Get an automatic transmissioned car, it will do your thinking for you.

When driven right you may never even hear your modded BPV vent... until it VENTS! appropriately... like at the shift point of a WOT run. That vent will be distinct, and almost surprising in quality.

But row your poor abused machine like a girl being taught how to drive a manual and your world will be a frustrating mix of clutch stink, jerky bobbing uneven progress, and weird noises from the sadly reined stallion under the hood.

My STi, in example, should flow forward. Authoratatively smooth and powerful, or elegantly regal and with grace. Until the time comes to unsheath its sword, and all hell breaks loose. An STi is not for amateurs. Those with lesser machines in imitation provide comic relief.

[isotopesope]

hmmm, interesting analogies. perhaps i am driving it inappropriately, or rather not adequately adjusted enough to suit the mod, or turbos in general? granted, this my 7th manual vehicle in 20 years, but it is my first turbocharged car. i have only driven n/a prior. it has taken a lot of getting used to the nature of this new beast, in many ways. i must say, personally, i don't often shift past 3k, and typically maintain moderate acceleration levels... even still, i found it hard to avoid that flutter. maybe i do drive it like crap and i am naive.

your earlier comment about not "snapping the throttle shut" had an impact on me, because i definitely have found myself doing that.

i must say though, that weird squeak is what was so unnerving, and i noticed it most often when not even getting into boost and driving super conservatively, without hearing it vent. the forge piece solved that noise, which i am grateful for.

[mechatricity]

Originally Posted by SeeeeeYa

I think some of the differing experiences of people who do this mod is the direct result of their driving... and a lack of understanding of how the characteristics of the modded BPV map onto that driving experience.

For example; knowing that their system will now maintain a boost level once developed (say 6-8ish psi), instead of always operating from square one, HOW one manipulates requested torque (mashes the pedal) changes relative to the same car without the mod. Drive without making boost and not much changes. But drive at a more moderate level that involves making a little boost and your pedal use and shifting changes. With the mod, you can make use of that resident boost by shifting smoothly and keeping torque requirements evenly flowing to provide a more muscular, but moderate, acceleration experience.

But ask for torque that involves the same boost, and all you wanted was that one moment of pedal experience so you drop back to where you should have been in the first place... and you get "flutter." It's telling you you didn't work the machine right. Like sticking a sharp stick in its ribs makes it grunt, instead of tapping it on the flank to let it know you want more forward motion.

If you drive to HEAR the BPV vent, you are likely abusing the car by driving amateurishly, and on a graph your requested torque inputs would be a sawtooth. The throttle is your voice, commanding action. Not a request for audience participation.

If you don't consider the changed machine the modded BPV enables, and ask for torque in an incorrect gear, you will push your turbo past its surge line, and get flutter. Again, uneducated pedal use. Get an automatic transmissioned car, it will do your thinking for you.

When driven right you may never even hear your modded BPV vent... until it VENTS! appropriately... like at the shift point of a WOT run. That vent will be distinct, and almost surprising in quality.

But row your poor abused machine like a girl being taught how to drive a manual and your world will be a frustrating mix of clutch stink, jerky bobbing uneven progress, and weird noises from the sadly reined stallion under the hood.

My STi, in example, should flow forward. Authoratatively smooth and powerful, or elegantly regal and with grace. Until the time comes to unsheath its sword, and all hell breaks loose. An STi is not for amateurs. Those with lesser machines in imitation provide comic relief.

You have quite the imagination.

[henria86]

I love this mod so much better response time

[ride5000]

what's wrong with flutter and surge?

been driving with that soundtrack for 100k miles at silly boost.

[greenplates]

An STi is not for amateurs ^