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Discussion Starter #1
I dont think the topic of Open vs. Closed BOV topic has been discussed in depth and would like to hear your experience. For clarification, I am not referring to the the bypass/recirculating BOV that can be found on the VT2 ESS kits for the E39.

Currently, I have a Tial 50mm open BOV (Open = BOV is open during start up). Although this might be the best performing BOV, it can become annoying and extremely loud when letting off the throttle. I have a vented hood, so i hear a lot more of it.

I would like to know if anyone has tested or is using a closed BOV with their SC Beast and are there any drawbacks. Open to hear both sides of the argument.
 

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im running a Greddy FV BOV, its a unique design as it has dual valves/diaphram's. if you're looking for quiet operation then this is the valve you want as it is closed at idle and always closed unless its dumping boost.
 

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For what its worth since I do not have a boosted M5, but have had previous turbo vehicles:

The noise levels when letting off throttle will not vary greatly whether using a open of closed valve. When generating boost pressure, both will remain closed, and will release as much pressure as they can per their design when letting off the throttle. The only way to mitigate this amount of noise levels is to recirculate the BOV to the intake, or route the released pressure elsewhere using pipes attached to the BOV.

Not related to noise levels, I did a lot of trial and error with a number of BOV's. I wanted to fix the fact that my turbine was experiencing surge or flutter when letting off the throttle for gear changes or deceleration. The flutter is a very bad condition since not enough pressure was relieved fast enough, causing the turbine to try and spin backwards. Using many of the top brands, I could still hear some flutter, until I used the Synapse BOV. It is the only one that totally removed turbine flutter, and was a normally open design which closed immediately when boost was present as it did not work off of vacuum but boost instead. It also had fittings if you desired to recirculate the released boost back into the intake system or route it elsewhere to the atmosphere.
 

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Discussion Starter #4
The issue I have is the constant noise when the valve opens and closes while driving. Lets face it, you cant drive on a constant speed for a long period of time and every time the throttle % changes i hear the whistling noise. It was cool in the beginning, but i cant take it anymore. Going back to recirculating version might be the solution for me, it doesn't look pretty, but it also wont scare people in the parking lots. lol
 
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Ah, so your BOV whistles when you let off even for slight throttle changes. I can see how that would be annoying. I never like BOVs that had whistling or chirping at any point of their valve cycles. The synapse one made noises, but more of just rushing air when opened. It was never noticeable at slower speeds, and only got loud when you really gave it the beans. I ran 19psi and only heard the air "wooshes" when driving spiritedly.

If you arent looking to change the type of BOV used, I would recommend recirculating. I cant see any other option with a vented hood that would attenuate the noise level from an exposed BOV.

Hope you find your answer Ruben.
 

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Discussion Starter #6

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get this Greddy FV man, i had the same issue with the stock ess valve. the whistling drove me out of my mind. this one is completely silent cause it is always closed unless it is venting excess boost.
 

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Discussion Starter #8
get this Greddy FV man, i had the same issue with the stock ess valve. the whistling drove me out of my mind. this one is completely silent cause it is always closed unless it is venting excess boost.

Are you able to post some videos
 

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Put a sock over it.
 

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Discussion Starter #10

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no, and even if i could you wouldn't hear anything anyway. just trust me man, i wouldn't tell you to get the valve if it didn't work and wasn't what you're looking for. the valve is called a floating valve as the main plunger opens when vacuum is applied to it but it has a secondary valve that is always closed and is opened only when boost needs to be vented. i've been running the valve for a couple months with zero issues.
 

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I have the same Tial Q-50 BOV on my RK Stage 1 kit. The noise off-throttle drove me crazy. Sock didnt improve much.

I bought Tials QR-housing ($60) and bolted it to the Q-50. Then I connected a 1" hose to the housing outlet and ran it to somewhere behind the front bumper, but still open. Noise is gone now! I guess I could connect it back to the inlet hose to make it a true recirculating BOV, but I dont need to.

I dont think the topic of Open vs. Closed BOV topic has been discussed in depth and would like to hear your experience. For clarification, I am not referring to the the bypass/recirculating BOV that can be found on the VT2 ESS kits for the E39.

Currently, I have a Tial 50mm open BOV (Open = BOV is open during start up). Although this might be the best performing BOV, it can become annoying and extremely loud when letting off the throttle. I have a vented hood, so i hear a lot more of it.

I would like to know if anyone has tested or is using a closed BOV with their SC Beast and are there any drawbacks. Open to hear both sides of the argument.
 

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Discussion Starter #15
I have the same Tial Q-50 BOV on my RK Stage 1 kit. The noise off-throttle drove me crazy. Sock didnt improve much.

I bought Tials QR-housing ($60) and bolted it to the Q-50. Then I connected a 1" hose to the housing outlet and ran it to somewhere behind the front bumper, but still open. Noise is gone now! I guess I could connect it back to the inlet hose to make it a true recirculating BOV, but I dont need to.
Sounds like something i might do. Can you post few pictures on how you routed the hose.
 

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Discussion Starter #17 (Edited)

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not hard at all man. you were able to get the tial welded on. removed the tial, weld up the hole, grind it flat, then drill new holes for the greddy.
 

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So SC kits on the M5 kits use BOV rather than BPV? My M62 blower kit came with a BPV instead. Your standard cheapie Bosch style unit. Mine seems to be working fine when I test it, but when I hit 11 psi and then go off throttle, the charge pipe sometimes blows out.
 

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