[2JZfan]

Originally Posted by DrH

I asked in another thred but I guess its more pertinent here... why a BOV instead of a diverter valve?
Another guy marketing diverter valves has this to say:

Originally Posted by Bob at Stratmosphere
1. Blow off valve sends the boosted air into the atmosphere rather than the airbox/air filter. It doesn't provide any performance gain and in most cases will trigger a check engine light.

It is also known in the Audi/VW world that everytime when you shift into a different gear under WOT, the engine will spike really rich

The check engine light and rich spike "issue" occurs only on mass air meter (MAF) equipped cars. The problem is that generally (but not always) the MAF is located before the turbo so it meters all air coming into the system (i.e. through the air filter). So then if you release some of this air to the atmosphere the computer is going to request too much fuel and you will go rich momentarily (the computer is providing the correct amount of fuel for the air that got metered, it has no way of knowing that only 80%, for example, of that made it to the motor).

None of this applies to the 335i, however, because it is a manifold absolute pressure (MAP) based speed density system. In other words, the only things that matter are the pressure and temperature of the air in the intake manifold. If you "blow-off" air prior to the throttle body, the ECU never knows this air "existed" and therefore won't be adding unnecessary fuel.

Outside of the EFI issues, some people feel that there are advantages to a recirculating blow-off (also called a bypass) valve as opposed to a vented-to-the-atmosphere unit like the Tial. The thought is that you have made it easier on the turbo because you are sending the air right back to its inlet instead of forcing it to suck the air through the air filter again. This is true, but I feel that it is a false economy of sorts. The much bigger problem is that the air has already been compressed, and thus heated, the first time it went through the turbo. Now when we recirculate it, it gets heated a second time. This makes the intercooler's job much harder obviously. I would much rather have fresh, cool, outside air used for each trip through the compressor.

And then of course there is the hard-to-deny "it just sounds cool" argument that justifies an atmospherically-dumping blow-off valve to 99% of the people.

One final thing to consider is that many blow-off valves are simply held open by manifold vacuum. So at idle, the valve may be open and therefore may allow unfiltered air to get directly into the motor (because with no boost there is no airflow going out of the valve to prevent this). Other valves, for example, the HKS super sequential, only open momentarily on the transition from boost back to vacuum. This is ideal because during normal idle and cruise the valve is closed, but when needed, it is open to the atmosphere. I have had 2 HKS valves on my car for about 5 years now and they have performed flawlessly. That's what'll be on my 335i!

[oldaccount]

Originally Posted by DrH

I asked in another thred but I guess its more pertinent here... why a BOV instead of a diverter valve?
Another guy marketing diverter valves has this to say:

Originally Posted by Bob at Stratmosphere
1. Blow off valve sends the boosted air into the atmosphere rather than the airbox/air filter. It doesn't provide any performance gain and in most cases will trigger a check engine light.

It is also known in the Audi/VW world that everytime when you shift into a different gear under WOT, the engine will spike really rich

What do you have to say about that? The reason I ask is I am trying to figure out which will work better in this car. Apparently different people have different preferences, but which one actually works best (ie gives the best performance gains?) We will probably have to wait and see. What I think MAY be telling is that the BMW people stuck with a diverter valve did they not? They must have had their reasons.

from what i understand, BOV's are pure, long grain, white rice, and dont belong on 335i's.

[PresaMat]

Originally Posted by Suareezay

from what i understand, BOV's are pure, long grain, white rice, and dont belong on 335i's.

+1

[2JZfan]

The whole "BOV == Ricer" concept is hilarious. I suppose then if you modify the exhaust to accentuate the engine's sounds that you are a redneck? Obviously nobody thinks that. So why is it that listening to one class of sounds from your car is "cool" and another class of sounds is "ricer"? Any real enthusiast will tell you that all of the performance-related sounds that a car makes when it's being pushed are a huge part of the driving experience. If you've never owned a turbo car then you might not know what you are missing. In addition to a blow-off discharge, the whine of the turbos and the rushing sound of air being sucked in are also two other highly addictive sounds that turbo owners become addicted to. Unfortunately for the turbo lover, BMW went out of their way to hide all clues of the turbo's presence.

And another thing, "ricer" is a wonderfully racist term that generally refers to mods that have no bearing on performance or function. For example neon, stickers, clear turn signals, etc. BOV's have a real purpose and of course your car already comes with hardware to perform this same function, it has just been purposely muted as much as possible.

[JustxOnce]

Originally Posted by 2JZfan

The whole "BOV == Ricer" concept is hilarious. I suppose then if you modify the exhaust to accentuate the engine's sounds that you are a redneck? Obviously nobody thinks that. So why is it that listening to one class of sounds from your car is "cool" and another class of sounds is "ricer"? Any real enthusiast will tell you that all of the performance-related sounds that a car makes when it's being pushed are a huge part of the driving experience. If you've never owned a turbo car then you might not know what you are missing. In addition to a blow-off discharge, the whine of the turbos and the rushing sound of air being sucked in are also two other highly addictive sounds that turbo owners become addicted to. Unfortunately for the turbo lover, BMW went out of their way to hide all clues of the turbo's presence.

And another thing, "ricer" is a wonderfully racist term that generally refers to mods that have no bearing on performance or function. For example neon, stickers, clear turn signals, etc. BOV's have a real purpose and of course your car already comes with hardware to perform this same function, it has just been purposely muted as much as possible.

+1

[boostmiser]

No offense, but why would you want a BOV boy racer sound on a 40K BMW? Why not purchase a Bailey or Forge DV (if they make them for this car, which I'm sure they do/will). Slightly louder than the stock, but definately not as loud as a BOV. They hold boost just as well.
http://www.baileymotorsport.co.uk/

[2JZfan]

No offense taken. I happen to sell turbos to customers all around the world including huge shops in Europe that have built the world's fastest street BMW's (making in excess of 1000hp). They don't seem to feel that this sort of mod is "boy racerish" and neither do I. There certainly is an element of personal preference that comes into play, but at the end of the day, trying to dismiss this as nothing but a childish gimmick is absurd. Why then do you find this same hardware on 2000+ hp domestic race cars? They certainly don't fit the "ricer" profile now do they? Again, I will use the exhaust analogy. You could make the exact same argument and say "it's a luxury car, you are paying all this extra money so that it is refined, quiet, etc.". But at the end of the day, the Ultimate Driving Machine should be that which provides the driver the Ultimate Driving Experience. This is obviously going to have a personal element. For myself and countless others, that is heavily dependent on the sounds involved. I think that those of you that take such exception to this type of mod must not have ever had any real experience with a powerful turbo car. Sure, if the only BOV you've ever heard was in the context of a 150hp Civic, you may have acquired some bad associations. The lowest hp turbo vehicle I have ever owned makes 800hp and to me, the sound of a BOV immediately conjures up the experience of driving that type of car at 150mph and grinning from ear to ear. Just because a part is used on a genre of cars that you feel is beneath you, does not mean that part should be excluded from all vehicles.

And furthermore, that Bailey piece is a BOV. Anything that dumps boost to the atmosphere is a blow off valve. There are no minimum decibel requirements, if it performs that function, that's what it's called.

[PresaMat]

I have nothing against BOVs when there is an actual improvement in performance by using them. If the car already has something that does it just as good then I see no reason to change it especially just for the sound. Now if I put a BOV on my car and it made a difference in performance (whatever kind... throttle response, HP, TQ, spoolup time etc.) more power to it. If the car is a high HP race car that needs a BOV thats cool... but I dont want to hear that sound if there is no real purpose for it. I hear it all the time on large big rig style trucks and it annoys the hell out of me.

[2JZfan]

Again, to each his own. I am the guy that literally rolls down my window when I'm next to a semi just to hear that turbo whine a little more clearly. At age 5 I already had my daughter able to identify which vehicles had turbos and which didn't based on the sounds. I am, plain and simple, a complete turbo nut. I won't deny that.

BUT, that being said, there are advantages to an aftermarket, larger capacity BOV. The first is that the quicker they are able to discharge the air, the less resistance is placed on the compressor rotation. A worst case scenario is a vehicle that has no blow-off, bypass, etc. When the driver lifts off the gas and the throttle body closes, the pressure has nowhere to go and will actually flow backwards through the compressor. This can be so violent that it can destroy the turbo. I have actually found pieces of compressor wheels stuck in the air filter on race cars from this type of flow reversal. The quicker you get rid of this pressurized air, the more the turbo is able to keep spinning unobstructed. Obivously a bigger orifice allows more air per unit time to exit. And not having anything attached to the discharge (i.e. vented to the atmosphere) provides the ideal pressure ratio to again improve flow. In addition to being easier on the turbo, the fact that the compressor wheel maintains speed better will help quicken the spool in the next gear.

The second benefit, as I already pointed out, is that by completely "throwing away" the already-compressed air, versus recirculating it, you don't have a scenario where you heat and re-heat the charge. Only cool outside air makes it through the turbo.

[boostmiser]

Originally Posted by 2JZfan

And furthermore, that Bailey piece is a BOV. Anything that dumps boost to the atmosphere is a blow off valve. There are no minimum decibel requirements, if it performs that function, that's what it's called.

Well technically, I believe the Bailey DV is more of a recirculation valve. It dumps the excess pressure back into the intake track vs. into the atmosphere. But maybe the make another product that is a BOV? Anyhow, I understand if there is a market, then make it. Just not my personal preference. And that's what it's all about, personal preference. Good luck.

[2JZfan]

Originally Posted by boostmiser

Well technically, I believe the Bailey is more of a recirculation valve. It dumps the excess pressure back into the intake track vs. into the atmosphere. Anyhow, I understand if there is a market, then make it. Just not my personal preference. And that's what it's all about, personal preference. Good luck.

I'm not sure where you are getting that idea from, look at the picture on their website:



First of all they call them "dump valves", referencing the fact that they "dump" to the atmosphere. Secondly you can just look at the valves and see that they are made to discharge to the atmosphere, they don't even have a place on them to hook up a hose in order to recirculate back to the intake (the air escapes through the "slots" on the red and silver ones, so how would you divert that back to the intake??). The blue one even has a horn attached specifically to make the sound louder than normal. Talk about "boy racer"

[Drag Limited]

any chance of maybe a SSQV flange or other flange options for some of us loud BOV fans?

[boostmiser]

Originally Posted by 2JZfan

I'm not sure where you are getting that idea from, look at the picture on their website:

Ok, they obviously started making several products which I was unaware of. The one I was referring to for VW/Audi's, which I used to run. It's the DV30 (p.4 in their brochure) piston recirculating valve...aka, diverter valve. Which is also what the stock 335i has. I ran it on a 1.8T Jetta and from what I remember, it made throttle response a tad better, it held the boost longer and I think I also got another 1-2 psi of peak boost. Also, the Forge unit was nice too because you could change out springs and rebuild when/if necessary.

[TommyBahama]

Originally Posted by Suareezay

from what i understand, BOV's are pure, long grain, white rice, and dont belong on 335i's.

[eurotekm3]

1st post on e90....


would the BOV kit void the warranty?

[Drag Limited]

Originally Posted by 2JZfan

The check engine light and rich spike "issue" occurs only on mass air meter (MAF) equipped cars. The problem is that generally (but not always) the MAF is located before the turbo so it meters all air coming into the system (i.e. through the air filter). So then if you release some of this air to the atmosphere the computer is going to request too much fuel and you will go rich momentarily (the computer is providing the correct amount of fuel for the air that got metered, it has no way of knowing that only 80%, for example, of that made it to the motor).

None of this applies to the 335i, however, because it is a manifold absolute pressure (MAP) based speed density system. In other words, the only things that matter are the pressure and temperature of the air in the intake manifold. If you "blow-off" air prior to the throttle body, the ECU never knows this air "existed" and therefore won't be adding unnecessary fuel.

Outside of the EFI issues, some people feel that there are advantages to a recirculating blow-off (also called a bypass) valve as opposed to a vented-to-the-atmosphere unit like the Tial. The thought is that you have made it easier on the turbo because you are sending the air right back to its inlet instead of forcing it to suck the air through the air filter again. This is true, but I feel that it is a false economy of sorts. The much bigger problem is that the air has already been compressed, and thus heated, the first time it went through the turbo. Now when we recirculate it, it gets heated a second time. This makes the intercooler's job much harder obviously. I would much rather have fresh, cool, outside air used for each trip through the compressor.

And then of course there is the hard-to-deny "it just sounds cool" argument that justifies an atmospherically-dumping blow-off valve to 99% of the people.

One final thing to consider is that many blow-off valves are simply held open by manifold vacuum. So at idle, the valve may be open and therefore may allow unfiltered air to get directly into the motor (because with no boost there is no airflow going out of the valve to prevent this). Other valves, for example, the HKS super sequential, only open momentarily on the transition from boost back to vacuum. This is ideal because during normal idle and cruise the valve is closed, but when needed, it is open to the atmosphere. I have had 2 HKS valves on my car for about 5 years now and they have performed flawlessly. That's what'll be on my 335i!

you sir are correct!

I hope/expect to see at least an aftermarket charge pipe flanged to use the HKS SSQV as it has always been the best atmospheric BOV IMO!

[2K5 325i]

Sick post!

The CP-E TIAL kit looks tight. What is the expected price to be?

and

Will the product negatively effect the performance of the car due to excess boost being "dumped" or will it not?

If two 335's raced, one with a CP-E TIAL BOV- and one without, (same driver) would there be .0001 difference in performance?

Many thanks ,
-Chris

[aznevoviii]

the BOV kit is not only for the sound effect, but it also helps car breath better. Stock rubber hose VS CP-E's Aluminum piping (larger than stock pipe) will breath better.

The price will be right around $350 ish...

Check with CP-E, call them up, and you can order it from there.

make sure you say your from e90post, and he will give you discount.

talk to Josh.

thanks

-John