[stratos_335]

Hi everybody,

I had some free time so I thought it was a good idea trying to change the wooshhh sound of my Synapse BOV because I was bored with the sound of it.

It is not easy to describe the sound of my BOV. The Synapse BOV has an outlet as an option to use it if you want to convert it into a diverter valve. If you have this outlet attached then the BOV makes a higher frequency wooshhh sound.

Here is the optional outlet attached to the BOV:




the sound is noticeable even with 1-2 psi and just gets louder at higher pressure when the air is released without changing its pitch.

I removed the outlet to see how the BOV sounds without it. It doesn't sound at all from 0-10 psi but it gets a hoarse deep sound above that pressure. It's OK if you want a stealth setup.

Here comes some engineering, some CAD designing and some machining. A piece of Aluminum will be machined so it takes the form that I want.

At the following pictures you can see the stock outlet and the new outlet I designed and manufactured:



And here is the new outlet:



The new air outlet has a conical shape inside and outside. When you reduce the outlet area then the air is compressed increasing its pressure. The goal was to create a whistling sound when the air is released to the environment.

I also crated 4 holes perpendicular to the main axis of the outlet. I also wanted to mill the upper side of each hole to create the whistling effect. but it was late in the evening so I packed everything to return home.

In order to replace the outlet you need to get the BOV off the chargepipe so that you can have access to the worm screw that holds the outlet attached to the BOV. When I was removing the BOV, the sealing o-ring at the bottom was cut in the middle and got inside the chargepipe (f@ck Murphy's laws). I removed the chargepipe from the intake and took the sliced o-ring out.

I installed the chargepipe and the BOV back and got out for some testing after warming up the engine. At lower intake pressure I got the same woosh sound as before. But after increasing the pressure the BOV started to have a subtle whistle when releasing the excessive pressure. The goal was almost achieved.

Here is the stock outlet during designing:




And here is the new one:





So, the next day I tried milling the top of the holes to create a whistling effect. The new redesigned part would look like this:



And the edge would have a knife sharp edge like this:



After 5 minutes of milling the new outlet looks like this:







The goal was achieved. The bleeding sound has now a higher pitch even at lower intake pressure without getting annoying. The sound didn't change dramatically but it changed into a higher pitch note.

Thanks

Stratos

[Brey335i]

You and Big Tom should get together and start cranking out 335i products

[vasillalov]

Sound clip?

[Focus]

Originally Posted by vasillalov

Sound clip?

Seriously..you didn't make this thread about how nice it sounds without a clip !~!~!

[Tee212]

cute

[Jeff@TopGearSolutions]

Originally Posted by vasillalov

Sound clip?

Originally Posted by Focus

Seriously..you didn't make this thread about how nice it sounds without a clip !~!~!

[Bullet]

Originally Posted by Brey335i

You and Big Tom should get together and start cranking out 335i products

[cwn23]

Epic fail if there is no sound clip!

[kdiggz]

so you made a whistle tip?

[Jeff@TopGearSolutions]

[import36]

Originally Posted by kdiggz

so you made a whistle tip?

...and the whistle goes woo woooooo!

[Zechariaha]

Originally Posted by Jeff@topgearsolutions

bahahahaha

[thebigragu99]

Originally Posted by import36

...and the whistle goes woo woooooo!

That's the funniest vid ever !! Whoo woo!!

[stratos_335]

It is very easy to get a video when the car is standing still but is has a much different sound when the car is moving. I'll try to get a video for you but I don't give any guarantee that you will notice the difference as there will be a lot of noise due to the open window when cruising...

I'll post a video, maybe tomorrow

[CALWATERBOY]

Originally Posted by stratos_335

It is very easy to get a video when the car is standing still but is has a much different sound when the car is moving. I'll try to get a video for you but I don't give any guarantee that you will notice the difference as there will be a lot of noise due to the open window when cruising...

I'll post a video, maybe tomorrow

Very nice indeed.

Now....can you mill for a dual or quad tone whistle?

Imagine a slowly rotating head driven by gas movement, varying tone and volume. Audodesk that for the ol' CNC machine.

[IcebergM4]

Originally Posted by Jeff@topgearsolutions

[Magic-Man]

No clip? Thread fail

[Bertholf]

Good Morning, my Name is William Bertholf and I would love to order one of your discharge flanges you made for your BOV, I have been looking for a way to change the sound, would you be willing to make one for me at a cost? Also by chance can you email me a sound bit of the BOV with your discharge flange on it?

Thank you so much my cell is : 757-634-4671, email: wbertholf@gmail.com

[rooringhusky]

I wouldnt mind one either. Seems like a small change that could be fun. Let me know if you don't mind making another please

[AMERICUS]

Wow, thread revived from 2011...

[Snypa]

...still no sound clip.