i have a flyin miata bov, and it sounds silly? it is recirculated. any where from 1/2psi and up it sounds like a turkey gobble:gay: . is this normal for this bov? are these known to be not good. since it is recirculated i expected it to be silent. other than the noise it seems to work fine.

 

I could be wrong. But I think it's your waste gate rod. I know with GReddy kits like mine they're notorious for that turkey sound if you don't tighten the accuator rod.

 

The "turkey gobble" is often the sound of compressor surge from your bov not opening enough to relieve pressure from the charge piping. You could try lubricating your bov or loosening the spring to make it easier to open.

 

Where do you get your vacuum signal from? If you have a weak vac signal it won't open much either and could possibly "flutter". My tial, which has a really strong spring, blows off clean at just about any boost level(1-2psi)

 

1 rod is tight. 2 how can it surge a 1psi? i thought surge happens at high compressor speeds. 3 signal comes off of a tb vac port; i read this is best place.

 

That's a good port to use I just wanted to make sure you weren't using a spider web of vac-t's for your signal.
Sounds like you need to clean and oil the valve and adjust the BOV spring tension.

 

only hundred miles on it.

 

spring can't be adjusted

 

Most the vacuum ports on the Miata intake manifold are too small to allow you to use a large enough vacuum line that will allow most blow off valves to function properly.

 

Ya same for me. I get compressor surge. That GFB BOV sucks ballz.

 

It isn't surging, its fluttering. The valve is just opening and closing rapidly... probably. Does it happen at any amount of positive, does it happen at the beginning of the discharge or at the tail end? What size vacuum line and is there anything else sharing that source?

 

does it really sound like turkey gobbling or wings fluttering? two very different conditions here....

 

It flutters because when the throttle closes the valve opens, relieves some pressure, closes, turbo is still spooling down because it's ball bearing, pressure builds even as it slows, BOV opens again and etc. until the turbo is spooled down. A really good BOV for a street application, where boost is "low" (like less than 20psi), will have a multi-chamber design and lower port that you run another vacuum line to, this alleviates this problem. Don't know if the FM BOV has this but if it doesn't, it should.

 

It could be as simple as the adjustment screw is just too tight....

"fluttering" is best described as the piston opening and closing rapidly...when the piston has too much preload, the vacuum in the chamber allows it to open, but the boost pressure is not enough to keep it open, so it rapidly opens and closes, and it sounds like fluttering...

this is flutter: http://www.youtube.com/watch?v=Y4bZHpT-L38

"turkey gooble" or compressor surge is caused when the boost pressure is not released out of the valve. It instead is released out of the intake, but first causes the compressor wheel to spin in the opposite direction....this is the noise you hear, it's bad for the turbo and why you have a valve to begin with.

this is surge: http://www.youtube.com/watch?v=nTnUaBWXm88

 

http://www.youtube.com/watch?v=W_Qul7MiImk&search=bov

 

I loosened and tightened mine and it is the same either way. Mine sounds more like the surge video out of the two that braineack posted.

 

it's your like this?

http://www.gofastbits.com/index.php?...b_option=basic

 

I'm really shocked by the DSM BOV's lack of prevalence in all the DIY setups. They can be had for anything from free, to $45 for a new one, will hold 18psi without so much as a leak and open normally every time. These **** ones that go on with a worm clamp make my skin crawl.

 

lots of people run them. and attach them with worm clamps.

 

How does the method of attachement really matter in how it performs?