BOV Setup for your N54

RuskiRacer

Captain
Jul 17, 2019
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If you don't like how the tial sounds with silicone inlets maybe get a gfb or a turbosmart? Its gonna make that noise with the inlets your just gonna have to live with it or get a different brand bov. 7psi spring is fine you can see it closes under boost and releases pressure very quickly.
 

IQraceworks

Corporal
Jul 7, 2020
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07' BMW 335i
Couple things:

1: BOV spring is fine. I wouldn't change it.
2: Log indicates -to me- tune is aggressive, and will use throttle control as a means of trimming a bit more than we typically see thus you're making the BOV do work. If you put a stiffer spring in you'll make the activation rate go down but you're aggressive. I assume this was done to make the car more responsive and I'm sure it works. Not shy with the WGDC.

Bottom line is I'd keep the BOV spring and ditch the tune. I'm sure it's a powerful tune and feels good but IMO it's aggressive.
The only thing that doesn't make sense to me is that I've tried several different tunes (this is the V5 E40 Stage 2+ MH OTS Tun)....and even with much milder tunes, I still get that hooting sound....and I can still get the BOV to flutter. Whatever it is....it sounds like it's reall common for some reason, and nobody has really found a "Fix" except when that change a whole bunch of things at once (new turbos, reloated inlets, aftermarket tune, etc, etc), and then the sound just magically goes away.....not knowing what really did it.
 

jareddlc

New Member
May 1, 2021
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Sorry if this was already answered, but which is the correct spring for the turbosmart bov? I may consider buying it.
 

martymil

Major General
Sep 6, 2017
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The problem with the orange is it let's the bov run almost fully open at idle.

The pink and purple is only just cracked open at idle which is perfect.

You get all the springs in the spring kit so try and figure out what suits your needs.
 

martymil

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Sep 6, 2017
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To answer a question sent by pm so I don't have to do it again

You run pink and purple together not just one spring.

One is smaller than the other but can
Be run together.
 

doublespaces

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Oct 18, 2016
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Here is a crummy video I took last night on my phone showing the BOV working. I don't see any real delay between throttle closure and BOV venting. You can hear that hooting sound a little bit...it's much louder when it's venting more boost. I was just doing a little easy power breaking to build boost....

As you can see...that 7psi spring really is too light, it's wide open and idle. My motor pulls around 19in/hg vacuum at idle....the 10psi spring really is ideal....but it makes the hooking/screeching sound even worse!

Thoughts?


BOV seems a bit lethargic? Normally they pull straight up and stick there until they go down. Your plunger is bouncing around like it's barely able to stay open.

Based on the video, I'd say that sound is occurring right as the plunger is opening or maybe even beginning slightly before.

I'm also having this issue. Happened right after when i installed the 2nd set of mods. Shop told me it could be due to the silicon inlets. They also noticed the change of sound of my BOV.

I was running the following for 2 years without any sounds.
- VRSF 5in intercooler
- VRSF chargepipe
- BMS dual cone intakes
- Tial BOV with plain spring
- 1 year later replaced all my vacuum hoses with 3.5mm silicon ones

I then installed the following, and the noise began immediately
- Pure600 turbos
- VRSF Silicon inlets
- VRSF outlets
- VRSF catted downpipes

I then did a custom tune and the sound was still there. Today i changed my spring to black and it was wide open on idle. Drove around the block and the noise was still present, i reverted back to the plain spring. I had made a video a few days ago to post for some help, i'll leave it here as well.


first clip you can hear a "flutter" and second clip, the "hoot"

I'm not sure what to do at this point to get rid of that sound.
What size/material vacuum lines do you have? Have you tested the lines and the manifold connection for leaks? Are you using a dedicated bung off the manifold or are you trying to use the stock nipple? How long are your lines? Any compromises here could slow or reduce the responsiveness of your vacuum

If someone wants to eliminate the spring from the equation entirely you could try the TIAL QRJ. They make an adapter for it if you already have a TiAL Q flange.

Random photo:
1623984087679.png
 

IQraceworks

Corporal
Jul 7, 2020
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07' BMW 335i
Keep in mind that the video I took of the BOV in operation was when I was doing some light power braking in my garage. The motor was only making a couple of pounds of boost.......I'm sure if it was WOT making 20psi, the BOV would have been open much longer....more boost, and a stronger vacuum signal when letting off the throttle.

All that aside......it still doesn't make any sense that with the oem inlets (the only thing that changed in the entire equation)....the BOV operated and sounded great! The only thing that changed was the addition of the silicone inlets.

Even under light throttle and low-boost conditions....I get a funny "hoot" noise now.......under WOT and big boost....it's a "screeeeech" noise.

I'm glad I'm not the only one who had this happen after installing silicone inlets......after searching online, it sounds like it's extremely common......and aside from completely changing their setup (new turbos, new tune, relocated inlets, etc)....nobody has ever found a fix, or even the actual cause. Just lots of speculation....
 

doublespaces

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Oct 18, 2016
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Keep in mind that the video I took of the BOV in operation was when I was doing some light power braking in my garage. The motor was only making a couple of pounds of boost.......I'm sure if it was WOT making 20psi, the BOV would have been open much longer....more boost, and a stronger vacuum signal when letting off the throttle.

All that aside......it still doesn't make any sense that with the oem inlets (the only thing that changed in the entire equation)....the BOV operated and sounded great! The only thing that changed was the addition of the silicone inlets.

Even under light throttle and low-boost conditions....I get a funny "hoot" noise now.......under WOT and big boost....it's a "screeeeech" noise.

I'm glad I'm not the only one who had this happen after installing silicone inlets......after searching online, it sounds like it's extremely common......and aside from completely changing their setup (new turbos, new tune, relocated inlets, etc)....nobody has ever found a fix, or even the actual cause. Just lots of speculation....
Have you tried a stock tune?
 

IQraceworks

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Jul 7, 2020
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Wouldn't running a stock tune on a car with DP's, inlets, E40 in the tank and all the other common bolt-on goodies cause all kinds of issues??
 

doublespaces

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Oct 18, 2016
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Wouldn't running a stock tune on a car with DP's, inlets, E40 in the tank and all the other common bolt-on goodies cause all kinds of issues??

I haven't been on a stock tune in a long time but can you flash stage 0 without checking the OEM downpipe option? Regardless that should only give you cat codes, which are largely superficial AFAIK.

The ethanol will create an issue but you don't actually need to drive your car to do this test so you should be fine since you won't be putting any load on the engine. I've driven an e50 tune on acn91 many times, I just can't get into the boost at all. Easier to do on a big single than twins though.

The other mods shouldn't create a problem as far as I can tell, you just need to fire it up and rev it a few times from a stand still right?

In any case, reverting back to stock inlets is obviously out of the question but the only thing I can suggest is to work backwards and eliminate as many variables as possible.
 

IQraceworks

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Jul 7, 2020
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I understand what you are saying.....but the only variables that have changed were the addition of the silicone inlets......BOV didn't change, spring didn't change, tune didn't change, etc,etc....

My new RB TWO's will be ready next week......so after I get those on, with the new custom tune.....I will have to see if I still have the same hoot-owl noise.
 
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RNM

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Jun 3, 2019
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I originally had relocated metal vrsf inlets and then switched over to bms stock location silicone inlets and the sound remained the same (sounds good, not like the owl sounds in this thread) despite using different bovs (tial and raceport). I am running larger td04 turbos, but I am not sure if they also play a role with how the bov sounds (I am currently using raceport as I am a ricer). :)
 

N54TT

Corporal
Jul 21, 2020
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Not sure if this is relevant or not, but I have relocated inlets and when I let off the pedal the first whoosh I hear is from the filters then I hear the Tial Q bov release right after. Any thoughts?
 

IQraceworks

Corporal
Jul 7, 2020
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Just an update.........just got my new RB TWO's installed, and I'm working on getting the custom tune all dialed in. Same squawking chicken sounds out of the BOV. I think at this point, I've just come to the conclusion that it's the nature of those silicone inlets.