How to Make a Loud BOV Quiet.
 

Wrap that bitch in foam.

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It's a lot quieter now. Just easing around town without boosting, I don't hear it. Before you'd hear it no matter what. If I get on it some and make a few PSI, I sometimes here it, but barely. Probably not audible from outside the car. Full boost, you hear it, but it's not much louder than at a few PSI. I'm gonna try wrapping a little piece of metal around the foam where the BOV vents tomorrow. This may make it quieter and will help keep from blowing all the foam out. Currently have 3 zip ties holding the foam.

The intake is now 10x louder than the BOV. Working on a solution there too.

I have to assume you like your cars quiet. I don't think you would enjoy my car! :giggle:

why didn't you just recirc. it?

ditto

LOL pat and his never ending quest for all things quiet:giggle:

Hahaha Someone wants a sleeper...

How to Make a Loud BOV Quiet.

Wrap that bitch in foam.


NOT...you probably reduced the flow by a good amount. BOVs or BPVs need to be fast-acting in order to shift huge quantities of air before the charge line between the compressor and throttle body shoots up in pressure, thus causing a reversal of flow and the resultant turkey gobble.

Use a bypass valve if you want a quiet BOV. If its good enough for Formula 1 and every single OEM or factory racecar ever made, its good enough for you. subaru has the best OEM bypass valve and you can have one for $20 if you look.

with his intake consisting of a 6" (just a guess) pipe I seriously doubt recirculating the air back there will make it any quieter...that is unless he'd extend the intake and install the stock airbox or something.


is that a heat shield you are working on in the first picture Pat?

Anything is quieter than a blowoff valve. I have a 6" pipe too and I can barely hear my bypass valve.

+1

Basically I couldn't recirculate it. At least, not easily. The intake is basically a filter on the turbo, with no room for anything else.

Yes I'm going for the sleeper look, and sound matters too. :fawk:

Whether it hurt flow or not... I really don't care. This turbo surges/flutters (whatever it's called) when I shift below 3500. That is, until the BOV finally stops dragging it's ass and opens. Still does the same thing as before with the foam, only now I hear "flutter-flutter-silence...". I should probably get a softer spring for the BOV so it will open sooner.

I'm gonna wrap the air filter in foam too after I build enough heat shields to feel safe doing it. Don't care if that hurts performance either. I want a quiet, reliable, fast car. In that order. :giggle:

Maybe. ;)

I now understand

if "some" users had let lazzer finish his electronic BOV this could have be remedied :)

Sigh. I agree. I PM'd Philip after he banned him and philip said drop it or I was banned. I know he's back now that philip is gown, but he doesn't post much.

Side note- I keep looking on google for info on how to make an intake quiet, and all I'm getting is "how do I make my intake louder"....

I think while browsing through FM's 700 some-odd (probably more now) pictures they have in their album, I saw a few of a car with what looked to be a large chunk of foam that was carved hollow with holes cut into it for air flow placed over the filter, and that it did a great deal in quieting the intake.....At least I think it was in FM's photos...

There are electric BOV's out there.. I've heard interesting good things about them.

Indeed, I've seen those pics. They even dyno'd a car with a FM cold air intake w/ and w/o the foam, and said the foam made no difference in HP. Someone else on m.net also did with and w/o the foam on a dyno and got the same results. Only thing is all these people that put foam on them have badass cold air intakes. I can't do anything like that.

:bowrofl: that is what you get when you try to go against the flow in a world filled with ricers

Hang in there Pat. I like my intake and BOV quiet too. I might even go to a *gasp* recirculating setup.

The stock BOV on the new GTI is electric, I found that out when installing a new BOV on my buddy's. Pretty nifty design, and I dident know they were electric.

increase the diameter of the flow cross section = lower mach numbers = quieter

http://gallery.y8s.com/d/423-3/bigbov.jpg

is that you? :bowrofl:

yes, OR use a pre-compressor throttle body mounted like that:


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Notice that this doesnt replace the actual throttle body which is still in the original location, but it closes in conjunction with it, thus removing any possibility of flutter. An e-BOV might be easier and simpler though.

Yeah, I bet I could port on this BOV a bit and make it quieter. Pretty sure it's designed to be loud.

GFB Electronic BOV

Super expensive though. :td: They also have the Stealth which is basically the same, but without the electronics. I've read alot of great reviews about GFB online.

Vash-

mine is a GFB I love it.. it is super loud though

hey pat, here's something for ya:

The All-Electronic Blow-Off Valve!

I also found a local supplier ;-) for the e-BOV @ $18.47 each:

Toro 1 In. In-Line Jar Top Valve with Flow Control (Slip) - 53707 at The Home Depot

The controller doesnt have to be so complex, just something that goes to ground at closed throttle since you don't run a MAF. Or even a vacuum switch if you want to get fancy.

Probably also depends on the kind of foam you're using. The samekind principles for making a firearm silencer probably apply. Another material worth considering is steel wool.

Well, I'm gonna do the intake next before I finish up the BOV. But I was figuring I'd wrap the BOV in another layer of foam, then wrap it in sheet metal and put a couple hose clamps. Might be too restrictive, but if so, I can make the steel band smaller. So we'll see. I'm not wanting to change BOV's right now. I can't while I'm at college.

I've read that even a long hose helps muffle the sound- and you can aim the exit. I haven't tried it yet... my eBay bov isn't that loud.

sexiest 1980s 1500hp 4cyl ever made if im not mistaken (which i prolly am)
bmw m12 engine?

I believe its a BMW, yes.

I bet a tube sock would work great, just double it up.

I had a lawnmower foam air filter on mine. That cut noise down by half... There's k&n style breather filters on eBay that will fit most bovs.

Did you use foam with a combustability rating? Wat if you backfire :( Some foam likes to burn.

Good point. Never heard of that. Link? This is walmart special foam. I'm sure there's something better out there, but I wouldn't know what.

I put a small piece on my manifold and it smoldered to nothing.

APS makes a good Recirc.

Pat, I agree with you about the noise levels. After I installed a midpipe and header, my car was much louder than I wanted. Before, I could step on it and not get too much attention, but now I get unwanted attention. The added noise isn't worth the 4-6 WHP that is gained.

Well if it just smolders it's probably flame retardant already. Why not hold a match to it? If it burns slowly it's the good stuff. If it goes WOOSHpoof then it's bad.

Here's a link to some foam:

Flame Retardant Foam

Why not just change the frequency? Stick a really big dog whistle on it.

my bov is rerouted and still loud as fuck.