Open Air or Closed Loop BOV

[Rocket]

Hey all!
Tired of the moose under my hood big time! I am getting ready to do a partial tear down and rebuild. Short story, water pump pulley separated from the water pump causing a timing belt failure.

In doing the tear down and rebuild (on a budget), I am looking at replacement of the moose sounding stock BOV. I wasn't sure whether to go with something that vented into open air or does it have to vent back into the air intake?

Thanks
Rocket

[Unknownvr4]

It doesnt have to recirculate, you can have a open atmosphere one but when you shift it will run rich because its venting air that the MAF already thinks is in the system. For some people, this causes stalling but all they do is bump the throttle and that fixes the issue. If thats too big of a deal for you just get a recirculating one.

I run a nice Tial 50mm BOV :D

[mb3000]

^What unknown said. Some people will argue that it should always recirculate, but the choice is up to you. If you want something loud than an open atmosphere is for you.

I am running and open atmosphere bov with an arc2 and have no issues.

[Unknownvr4]

Oh yea... the issue is only there on the stock MAF.. If your blow thru or anything else you should be fine...

[KeithMac]

I`ve been reading up on this recently and running rich between shfts can actually have the benifit of staving off knock.

I bought my car with an open bov and it`s never stalled out on me..

[rawavr4]

I recommend the Forge bov from DR. Its $160 brand new and works great. No diaphragms to blow out like some GReddys.

[deemo99]

A Tomei bov fits with no mods also, doesn't draw any attention. Have not tried open with arc2, hrmmm....

[Rocket]

I`ve been reading up on this recently and running rich between shfts can actually have the benifit of staving off knock.

I bought my car with an open bov and it`s never stalled out on me..

I'd like to know how this would help stave off knock? The only time I ever see high knock count is under high boost. Going rich with the throttle off or during the closing of the throttle just after a big boost isn't one of those times I ever saw any knock. I am not discounting what you have said, but I would like to see some more information about it.

I have been looking at some of the HKS models right now. Will check out some of the ones listed and see what they are about. I may look at something that I can open air or modify closed/recirc. If things don't go well open air I can then always go back to closed system. I have the original MAF in place and I am not running any fuel management other than the stock ECU.

We'll see what else the thread sparks in conversation. I am interested in hearing some in depth on this :)

Rocket

[CoopKill]

Any time your running rich or lean it's not beneficial to long term health. Running rich leaves deposits throughout the system and fouls plugs prematurely.

My choice is to remain closed loop. Besides, the car attracts enough attention without the f and f whistle. Just wave out the window as you pass.



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Tapatalk Bitches! :transform:

[KeithMac]

If you drive the car hard between shifts (track work or 1/4 mileing), the extra fuel helps cool the chambers and also prevents lean tip-in. If you just do a pull then coast down it will have no benifit. Quite a few race cars are mapped to run rich on overrun to improve the reliability under extreem driving conditions.

You will never see knock throttling down, but cutting fuel can set up conditions to knock in the next pull if it`s done instantaniously.

Normal road driving wouldn`t benifit much as you say.


I'd like to know how this would help stave off knock? The only time I ever see high knock count is under high boost. Going rich with the throttle off or during the closing of the throttle just after a big boost isn't one of those times I ever saw any knock. I am not discounting what you have said, but I would like to see some more information about it.

I have been looking at some of the HKS models right now. Will check out some of the ones listed and see what they are about. I may look at something that I can open air or modify closed/recirc. If things don't go well open air I can then always go back to closed system. I have the original MAF in place and I am not running any fuel management other than the stock ECU.

We'll see what else the thread sparks in conversation. I am interested in hearing some in depth on this :)

Rocket

[TonyM]

If you're running a MAF, recirc it, vented runs like shit.

It may 'seem' fine, but after running my Greddy open for awhile, and then back to recirc it was night and day. If youre on a MAF, keep it looped, you'll thank yourself later. It isn't worth the tradeoff just for some ricer sounds.

[Rocket]

They stall becuse the BOV is open at idle (air flows into it) and air bypasses the AFM.
Sure you can tighten the spring (aftermarket) but that defeats the purpose of having a BOV in the first pace.
Likewise you can bump up the idle speed but it's still got air bypassing the AFM so it's still broken.

Steve

Ok good information. My understanding of how the BOV works was off. I assumed it was in a closed position all the time. That the on deceleration vac drop cause the controller (stock or aftermarket) to open wastegates and cause the BOV to open until pressure equalizes and the BOV would be pulled closed again. If I understand what you are saying correctly then there would never be a reason to run a stock system on open air. At idle it would be running too lean as unregulated and unmeasured air enters the system without any extra addition of fuel since the computer doesn't see the extra air in the system.

In a perfect world I would replace the stock MAF with a blow through setup and run an AEM and not worry about it. But if this information is correct then I close the loop and recirc the BOV :)

Thanks
Brandon

[green-lantern]

They stall becuse the BOV is open at idle (air flows into it) and air bypasses the AFM.
Sure you can tighten the spring (aftermarket) but that defeats the purpose of having a BOV in the first pace.
Likewise you can bump up the idle speed but it's still got air bypassing the AFM so it's still broken.

Steve

Wait what? The blow off valve is open at idle? LOL

[CoopKill]

They stall becuse the BOV is open at idle (air flows into it) and air bypasses the AFM.
Sure you can tighten the spring (aftermarket) but that defeats the purpose of having a BOV in the first pace.
Likewise you can bump up the idle speed but it's still got air bypassing the AFM so it's still broken.

Steve

Please don't post ignorant shit like this. You are going to f somebody's ride up that takes it seriously. If your BOV is open on idle, that is one bitch of a vacuum leak!

[mb3000]

They stall becuse the BOV is open at idle (air flows into it) and air bypasses the AFM.
Sure you can tighten the spring (aftermarket) but that defeats the purpose of having a BOV in the first pace.
Likewise you can bump up the idle speed but it's still got air bypassing the AFM so it's still broken.

Steve

1. We aren't talking about running rich at idle.
2. You can't believe everything you google search.
3. Do you think BOV's are "rice" just like aftermarket FPR's?

[CoopKill]

So, then if running open atmosphere the ecu must be using the o2's to keep from going lean on idle since mas is not seeing air introduced through open bov?



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Tapatalk Bitches! :transform:

[DocWalt]

Stock BOV is open at idle and during cruising. A lot of aftermarket BOVs that are designed the same will be open at high vacuum as well. Any car using a draw-thru setup runs like crap without being recirculated, even if you tune for it.

[blindmist]

Don't listen to a word steve says. He is wrong 99% of the time and only adds info that will fuck peoples shit up.

Having said that. I have run both recirc and open plenty of times. It does not affect my car either way at all that I can even tell. The logs are identical as well and you cannot tell the difference on those either. Having said that, if your BOV is leaking at idle and air is getting through, you need to replace it. My OPEN BOV doesn't leak shit when it is closed, so I have no idea what the hell he is talking about.

Also. I am still running my MAF. I think there are more variables to the BOV recirc or open as to where you are altitude wise. I am at 3300FT.

[blindmist]

That's what the o2 sensors are for.
It's to maintain the AFR in closed loop mode. By having an open BOV you're screwing the fuel trims which in turn screws the tune. The fuel trims can only compensate so much before they're pegged out.
As for BOVs being ricer items, the best ones are factory ones found on late model evos.

Steve

If you set your fuel trims with an open BOV, the ecu has no idea. The fuel trims will be spot on.

And like I have said, if you have an open BOV at idle, you need to replace it, how the fuck do you think it is going to hold boost if it can't maintain a seal with VACUUM?

A BOV (should) only opens when there is vacuum on the small side and boost on the large side. It is (in theory) similar to a Master Brake Cylinder. There is vacuum on one side, but it doesn't move until you push the pedal.

[Nihil]

Maybe Someone Should Read -->This...<-- (http://www.stealth316.com/2-bov1.htm) Jeff's Site Is Always A Good Source Of Info...And To Quote Jeff...


Problem with stock BPV: Why replace the stock by-pass valve (BPV)? Because it leaks. It is designed to leak. As shown in the pictures below, there is a hole in the face of the valve that is designed to allow air to flow at all times from the Y-pipe through the valve stem and into the intake hose. Another design "feature" is the plastic valve and seat. These two parts do not fit together tightly and there is no rubber seal. So air leaks around the valve face and into the intake hose. To determine this, I lit a match and extinguished it, filling the opening of the BPV from the Y-pipe with smoke from the match. Without creating any pressure I could see the smoke leak past the valve. Mitsubishi probably thinks a "leaky" BPV is a safety feature, and it might be in order to limit boost somewhat in a car that is stock except for an owner-installed boost controller. However, for the owner that likes more precise control of the by-pass air, an aftermarket valve is preferable.

This would be the only thing I could see to be "misconstrued" as an open BOV.

Just as blindmist said
how the fuck do you think it is going to hold boost if it can't maintain a seal with VACUUM? Which is why the stock one sorta sucks...it doesn't fully seal.

Has anyone checked this out? Anti-stall GReddy Type RS Module (http://www.atpturbo.com/mm5/merchant.mvc?Screen=PROD&Store_Code=tp&Product_Code=ATP-FLA-015&Category_Code=BCS)

[TonyM]

I suppose my question to all those advocating venting to atmosphere on a MAF intake system is this: what's the benefit of doing so?


Bottom line, whether your car shows any poor performance or not, there is no benefit (unless you consider the "sound" a benefit . . . perhaps some whistle tips are in order?). I'd venture that more often than not, BOVs exhibit minor leaks in high vacuum scenarios.


And like I have said, if you have an open BOV at idle, you need to replace it, how the fuck do you think it is going to hold boost if it can't maintain a seal with VACUUM?

Are you aware of how BOVs operate? The valve is held closed when under boost as the high pressure intake charge holds the valve shut. When lifting, the sudden pressure change from postive to negative pressure opens the valve. Leaking under vacuum has no bearing on whether or not a BOV would leak under boost. Leaking under boost would be indicative of poor design or defect, but the postive and negative pressure scenarios are completely different. And the bottom line is, the only reason a minor leak under vacuum would cause an issue is if you were running an open BOV with a MAF. Recirc or speed-density cars wouldn't see any ill effects. Remember, these are cheap valves by most standards, everything short of a Tial probably leaks a bit.

At the end of the day, if anyone here is honestly advocating running a vented BOV with a MAF then you're not after any performance benefit because there isn't one. If you truly must run a vented BOV to get achieve some Fast and Furious sound effects, buy the proper electronics to run speed density.

And whoever said speed density cars need to constantly be 'retuned' is clueless and obviously has never run speed density.

[green-lantern]

Yet another who is too (well 2 more) lazy to go out to the car and do some first hand tests with a factory open BOV. Stop posting crap until you've done so. It's vacuum that opens it.

Steve

Wrong! It's vacume PLUS the built up pressure from the turbo that opens the valve.

[Nihil]

I am looking at replacement of the moose sounding stock BOV. I wasn't sure whether to go with something that vented into open air or does it have to vent back into the air intake?

Thanks
Rocket

Lets skip all the sandy vagina talk and go back to basics and the solid answer...

Our system works like this, air flows through MAF, is measured and fuel is adjusted accordingly by factory ECU, when you let off gas, BOV opens and dumps air out, recirculating it into the intake system. Now, if you change that system and run Open Atmosphere, it dumps the measured air out of the system, you lose metered air, so now, you've got more fuel than air, because the ECU made it's calculations with that air you just dumped to atmosphere.

Different people/cars have different results, a lot of it has to do with driving styles and stock vs. aftermarket BOV. If you're running speed density or blow through, those systems are able to run open. Blow through setups usually have the MAF up close to the throttle body and the BOV before it, so when it dumps the air out, that air hasn't even been metered yet so it has no effect on tune, and speed density uses a Manifold Absolute Pressure sensor to measure air differently (just as the name entitles) and is usually measuring air at the manifold, that's why those two systems are able to still run (though shitty) when/if any piping comes apart or you have big boost leaks.

Ultimately though, running open is more for sound than performance, most of the time, when running high boost applications, does it then become more benificial to run open, because it gets rid of the excess air quicker to avoid boost spikes and surges, and you'll see some people run two BOV's to vent quicker as well, these individuals are also going to be running an aftermarket fuel system tuned properly as well...obviously, so these cars are more able and equiped properly to do so.

As for quality of BOV, any name brand is going to be good, it's the knock offs you gotta avoid, though the deal may sound good, if you buy one, you're really no better, if not worse, than the stock because it's designed to leak and a good 50% of those knock offs leak as well, and some much worse, to the point they won't hold a steady boost pressure no matter how tight you have it, because the seals are so flimsy.


Yet another who is too (well 2 more) lazy to go out to the car and do some first hand tests with a factory open BOV. Stop posting crap until you've done so. It's vacuum that opens it.

Steve

Sorry, you're right, Jeff Lucius is a total and complete moron, his website dedicated to our cars is completely worthless, forgive me?

To quote Erik Gross:

Sometimes the stock BPV is not sufficient to hold boost pressure when boost levels are increased beyond the stock settings.
The stock BPV has a hole in it (by design) and thus leaks air all the time. Note that this may have been a "designed this way on purpose" thing - modifiy it at your own risk

Yet another idiot who hasn't contributed anything at all to our platform :rolleyes3:

Stealth316.com BOV Explanation By Jeff Lucius (http://www.stealth316.com/2-bov1.htm)
Erik Gross' BOV Explanation (http://www.supercar-engineering.com/rubberducky/3S/Mods/TT/GrBPV/index.html)

[Atrosity]

Look it is god damn simple, this thread is dumb, if you have a stock maf then you run a recirculated BOV, if you run open loop on stock maf and just plug the other hole, then I will call you a ricer. If you want to run open loop then run it the right way. Get blow through pipes/gm maf or run speed density. If you are not running this set up then you need to recirculate it.

/thread

that's it.

[Rocket]

Ok the thread isn't dumb just some of the post have been sub-par. I found what I was looking for from it and that is good. Anytime there is a discussion on forum online you have to pick through the BS and pissy posts to get to the good information. I hate that it dredged up some bickering, but that happens. The technical posts are what I was looking for to begin with. I like to know why and how something works so I actually understand the part and its relationship to the rest of the system.

Sometimes a factory does something to appease gov regulations and other times it has a true function to work they way it is. The stock part in this case is not very good either by accident or by design. I will replace it and move along. Probably with something I can run in either function so with later fuel and management upgrades I don't have to spend money on something I am replacing now.

I thank all that have posted and appreciate the time you took to put in a reply.

Brandon

btw look forward to meeting many of you at the NG this year!

[a2j]

I got rid of the stock bov and was venting air to the atmosphere for 5 years now. no problem whatsoever.

[GTOJOE]

When I bought my car it had a Blitz set that had a vento to atmo bov and still retained the stock plumb back unit. Si it was using both why I don;t know but it worked fine and had no issues. When I suspected my old stock lastic bov was leaking [hooting owl] I removed it and just ran the Blitz atmo one and now have issues. I will be converting it to a plumb back system or locating an evo bov.I would love to know how other ppl manage to run vent to atmo without issues. Maybe the spring on my pos blitz is too weak.

[blindmist]

Jeeze you guys are thick. All you do is regurgitate shyte that you've read on the interweb.

No first hand testing?

At idle there's enough vacuum to lift the valve off it's seat against the spring so it's open, it leaks.
The hole in the middle goes nowhere,(why don't you test it yourself?) it's got nothing to do with leaks, again very easy to test yourself. A leaking BOV has advantages in certain situations as it will increase the airflow through the turbo without an increase in boost and therefore reduce the possibility of surging.



You do realize that there is vacuum on both sides of the valve during idle correct? Which should continue to hold the valve closed. Just like I was saying about the Master Brake Cylinder. There may be vacuum on one side, but it doesn't move till there is force in the same direction applied on the other side. If you have a BOV that leaks at idle, it needs to be replaced. Who said I didn't go out to my car right now, start it up, and test for leaks on my BOV?



Wrong! It's vacume PLUS the built up pressure from the turbo that opens the valve.

BINGO!!! We have a winner. 17Hg-in should not be enough vacuum to even budge a BOV. It need to have the 17Hg-in PLUS 0psi> on the other side of the BOV to open. If the vacuum alone at idle moves the valve, IT NEEDS TO BE REPLACED.


Jeeze you guys are thick. All you do is regurgitate shyte that you've read on the interweb.

Coming from the guy who thinks 90% of your problems are busted ring lands and everything needs an engine rebuild.
Who wants to start a tally on the ABSOLUTE FUCKING RETARDED SHIT steve says? Ill help start, the tally is already in the 50's or so.

[J_Parker]

Jeeze you guys are thick. All you do is regurgitate shyte that you've read on the interweb.

Steve, I'm not going to tell you to STFU&GTFO this time, because you do at times have very useful input, try being a little more polite to the people on here, and chances are good they'll return the favor. It seems to me that you fly off the bloody handle every time someone says something that opposes your input...

My Dr. Phil rant is done. Nuff said.

As for me, I have (had) a stock BOV and an HKS raceport type BOV hooked up to recirculate and vent to astmosphere when needed. But when I finish my biild I'll be going straight atmosphere with an HKS SSQV.

[Rocket]

OK this thread is deteriorating very quickly from something useful to a pissing match. If I could find a way I would hit the close button now. I will be posting more questions shortly to debate on, but I would like the debate to be full of useless boring technical information and personal antidotes about how it effects your car :) I am not pointing fingers and won't either. But please keep the personal nature attacks out of my threads please? You don't have to agree with each other, but you can post opposing opinions without falling to shit throwing :)

Thanks!!!!

If a mod wants to close this thread that would be fine. There is some good information in here and I hope it helps someone else out. When I get the old BOV off I will play with it and find out exactly how it works myself and then maybe post up something on it with pics ;) :)

[blindmist]

You're the winner

Haha, wow. Come up with your own stuff maybe?

I'll let my reputation on the board stand as my credibility.

[Lithium]

Mitsubishi used a recirc system for its draw thru setup thus it should stay that way. Mitsu put more time and money into R&D then anyone on this board (excluding the vendors). Venting to atmosphere offers no performance benefits yet may yield poor engine characteristics, knowing this the idea shouldn't be entertained. venting to atmosphere should only be done on blow-thru and MAP setups, even on those setups the performance gain is slim to none. That being said I personally have a blow thru with a vent to atmosphere setup. I'm glad I have a 4runner to drive daily because my BOV could get annoying real quick.

[J_Parker]

I have one on the Soarer that is vent to atmosphere, and I am happy as hell that it's an auto, they do get irritating quite quickly if you have one that doesn't sound good at all.

[Patryn]

Get one of the blow off valves you can switch between the two, open or closed loop. Synapse, HKS SSQV, and Tial QR come to mind. I seem to have less to no compressor surge running the synapse in closed loop verses running the old HKS SSQV open loop on my car. Either way there are a lot of bov on the market which allow you to switch between vented and non-vented.

[IPD]

ok, rather than start a new thread, i'm going to resurrect this one.

i'm going to a GM MAF in blow through (BOV immediately before the sensor). now i'm content to run open or recirc, but i'm not aware if there's any methods to keep it recirc w/o keeping the stock bubble. i get the impression that running recirc eliminates the need for "surge tubing" (which, as it was pointed out to me, is essentially a constant boost leak). i'm also looking to keep surge levels to a minimum. i'll be running an FMIC & a td05 kit; so i'm not sure that it's possible or even advisable to keep the stock bubble. i'm also unsure if it's better to get separate intakes for front/rear, or to stick to 1 combined intake. any suggestions/advice? i need to figure out what i want before i pull put down a couple hundred on a new intake.

[Nihil]

most blow through setups are vented to atmosphere and have individual intakes for each turbo from most of the setups I see. I'd start another thread specific to blow through setup and vented bov vs recirc. Yer gonna get people all excited in this thread and argue again lol