BOV placement - your thoughts.

[Tiwing]

I just found out all the SMRT people hang out here now! ... So, let me ask you:

As far as i know, there are 2 schools of thought on where to properly place a BOV or recirculating valve.

1) is within 14" from the throttle body. The reason for this is to allow the reverse pressure wave coming from the TB to be released sooner, and allow air that is still being pushed by the turbo a place to escape.

2) is that it should be placed on the pipe immediately after the turbo, in order to best release turbo compressor surge that would result from the throttle body being closed.

In the case of a plumb-back, the return line should always go into the pipe before the turbo.

MSP uses approach #2. I've converted my MSP to #1, with no ill effects. My GTX uses approach #1 stock. I have an option to do it either way on my GTX. Which approach do you believe is best... From what I know and have learned I'm leaning towards #1 - plus it's a little easier to make it work in this position on the B6T motor.

[CasopoliS]

two things to think about

if you are venting the BOV, you are venting mostly hot air on the hot pipe, and cold air on the cold pipe.

To me, ideally you would keep the cold air in the system.
My BOV is on the cold pipe and I recirculate hot air off the pipe. That is just how it was setup... I think either way would work.

Also, many people have moved the MAF close to the TB, and many add injectors close to the TB.... so if there is a BOV there it might take up space for future modifications. Just another thing to think about....

[RyanJayG]

the whole reason for a BOV is two fold.... help reduce re-spool-up time, and preventing compressor surge... the best place to prevent the surge is as close to the turbo as possible. This is why they exist, not to sit in the top of the engine bay looking cool.

[Mr.Win]

http://www.msprotege.com/forum/attachment.php?attachmentid=69183

i find this works best. Assuming that you want to vent, with these cars recirc would be best.

[Tiwing]

broken link.. the attach IDs only work from within the board i believe. It's for my other car though, I'm happy with my dual port on my msp. :)

[Mr.Win]

fixed

[CasopoliS]

I agree with Win

but only if you recirc off the cold pipe. IMO you really really need to recirc at least some of that air in our cars.

Talk to 505, he has done many many BOV/BPV setups. Hell he even ran two BPV's once. He has sounds clips, etc.

[505zoom]

...Talk to 505, he has done many many BOV/BPV setups. Hell he even ran two BPV's once. He has sounds clips, etc.

Haha, and I am actually running just a single BPV on the hot pipe for now.(boom7)

Just put it wherever will be cleanest on your setup. I really haven't seen much difference in performance by switching the valve location, and I've ran with valves on both ends of the pipes, both towards the middle, etc. Since you are venting out of a pressurized pipe, it's going to perform very similar no matter where it is.

[BRIAN MP5T]

By the book it's supposed to be a the TB...

[Jeph]

Interesting discussion. To me it seems to make more sense to put it near the turbo since you are mainly trying to fight off compressor surge, closer to the turbo would be better.

[BRIAN MP5T]

That is why I disregarded the BOOK

[Tiwing]

Brian I was waiting for you to chime in. 505 too, I read (and learned) a ton from you. I've also read "the book". I'm glad y'all have so many different opinions! The one I like best is 505's, " Just put it wherever will be cleanest on your setup.". Makes sense to me. :)

[Peepsalot]

Yeah, besides the whole before MAF vs after MAF issue, I really can't see the placement making a significant difference.

[Killer 8]

i would think it would be best to put it behind the BOV so the gain and lost of boost would be read at a point that it can get the right reading before it gets to the chambers

[Mr.Win]

I agree with Win

but only if you recirc off the cold pipe. IMO you really really need to recirc at least some of that air in our cars.

Talk to 505, he has done many many BOV/BPV setups. Hell he even ran two BPV's once. He has sounds clips, etc.

Well you take that placement along with blow through MAF close to the TB as possible and your money IMO

[505zoom]

As far as I see it based on flow and physics, it is better to release the air closer to the TB. I will try to explain my thought on it...

Since you "cap" off the intake pipe at the TB when you shift, venting close to there will allow all of the air in the system to remain travelling in it's natural direction through the pipe and towards the motor. If you vent out of a pressurized pipe near the turbo, then the air might try to reverse itself briefly to go towards the valve (high pressure vs lower pressure theory), in turn hindering the airflow to SOME degree.

Like I said earlier, I have seen little to no difference by moving the valve around, so I want to emphasize the "to some degree" part. I am just going off of physics theory here, purely for the sake of arguement. In my honest opinion at this point in time, put the BOV or BPV wherever it will fit best for the particular setup. Signal line to the valve should be taken into consideration and should be as short as possible, and then you just need to decide whether you want to show it off or hide it.

Just my opinion on it.

[JDM Sam]

Yea, it doesnt really matter as long its between the tb and turbo and the valve has a good strong vac source to open it. The msp seems to like bovs on the hot side more though from my experience, but the downfall it discolors the hks housing b/c of the heat.

[Mr.Win]

Speaking for the msp i think the set up i posted would be best for venting. If using a BPV then i agree with 505

[BRIAN MP5T]

i would think it would be best to put it behind the BOV so the gain and lost of boost would be read at a point that it can get the right reading before it gets to the chambers


No, Basically,

Moving the Mass Air to directly before the TB would allow for the most accurate read.

I had issues with my Fuel Injectors so I wanted to keep it a bit further than I would have chosen.

[BRIAN MP5T]

As far as I see it based on flow and physics, it is better to release the air closer to the TB. I will try to explain my thought on it...



Your post is 100% Max Boost Logic.

Fath of flow. In mine, the air is forced back and forth because my BOV is at the turbo.

Sometimes you have to choose the best for you and not the best in theory. :)