quieting down a bypass valve

[Maynor]

If you're not running the bypass plumbed in recirculation mode, a filter does help quiet down the noise. Note: it only quiets it, its still very noticeable.

I agree with Chris, the filter does act as a slight restriction but I was also using a very small filter. I'm sure if I spent more time plumbing the space for a bigger one, it would not be such a big deal.

I'm using a Procharger Big red recirc. bypass, without the recirc hose connected. If I had to do over, I'd have the discharge face up towards the hood instead of down towards the ground because it kicks up a LOT of dirt and dust even at idle which makes it impossible to keep the car clean.

John

 

[01greycobra]

^ It's only six screws that hold it, you should just be able to twist it. I was running a Procharger Big Red open valve and it was noisy as hell with air bouncing off of everything under the hood. I have switched to a Big Red recirculating valve now and run it open. The air going in one direction and not bouncing off of anything has quieted the car down alot. Still loud as hell, but nothing compared to what it used to be.

 

[bullittbuild]

Mine isn't too loud. BOB can you post pics of yours here is mine

 

[B0B]

i wonder if it being too restrictive is what caused the bearings to go out in my head unit???? i had 250 miles on my new motor when the bearings went out, the procharger was fine when i put it back on the car with 10k ish miles on it.

all my setup consists of is two stock procharger bypasses, i welded an extra pipe onto my dishcarge tube thats right after the head unit, then put another stock procharger bypass on it. seems like having two of them would be enough to compensate for 16+ psi right? they're just vented to the atmosphere and they are really loud. i would consider a big red recirculating type with a filter on the end but would that be enough? this setup is gonna make around 20 psi

 

[Chris98vobra]

i wonder if it being too restrictive is what caused the bearings to go out in my head unit???? i had 250 miles on my new motor when the bearings went out, the procharger was fine when i put it back on the car with 10k ish miles on it.

all my setup consists of is two stock procharger bypasses, i welded an extra pipe onto my dishcarge tube thats right after the head unit, then put another stock procharger bypass on it. seems like having two of them would be enough to compensate for 16+ psi right? they're just vented to the atmosphere and they are really loud. i would consider a big red recirculating type with a filter on the end but would that be enough? this setup is gonna make around 20 psi

The two stock bypass values may not be enough. I doubt it would cause the bearings to go out but it could cause belt slip on shifts and deceleration. You are also likely losing boost through them because the stock ones aren't designed to seal off as much boost as you are running.

I think I finally got my blowoff as quiet as it will ever be. I routed the air through large radiator hoses to behind my headlight and connected one of these.

It is K&N RU-0820 with dimensions of:
Flange Inside Diameter: 2.438 in (62 mm)
Flange Length: 0.625 in (16 mm)
Flange Type: Centered
Height: 6 in (152 mm)

I can still here a little rushing sound but the filter will flow more than the blowoff and pipe going to it so I know it isn't going to restrict. Not sure of anything else I could possibly do.

Chris

 

[MKSVT]

The filter at the end of it does nothing for sound and if anything restricts the airflow from exiting to a degree.Procharger includes mini filters with some kits just for a cleaner look under the hood. Your best bet is to run it closed. Procharger makes and open and closed version of the race valve for a reason.Compressor surge will not only kill your headunit in self contained applications it will do some damage on the seals. Ive had this happen to me and wound up not only paying to have the blower rebuild but having to buy a bigger valve aswell.

 

[Maynor]

The filter at the end of it does nothing for sound and if anything restricts the airflow from exiting to a degree...

I disagree with the first point and agree with the second. I ran a small filter at the end of a cut down radiator hose and it definitely quieted down the discharge sound. Not as much as routing the discharge to the intake but noticeable enough.

However, the small filter does act as a restriction and belt slip issues occured occasionally. I think the way Chris98Vobra did it it is probably as ideal as it could get if you wanted to keep it open to atmosphere.

That being said, I stopped running a filter all together and live with the noise. The whoosh I don't mind. Its the high-pitched whistle (different than the supercharger whistle) I've never been crazy about.

John
Novi'd 99 Cobra
LS2 M3

 

[Chris98vobra]

The filter at the end of it does nothing for sound and if anything restricts the airflow from exiting to a degree.Procharger includes mini filters with some kits just for a cleaner look under the hood.

Not correct. As I said earlier I tried the small one and it DID decrease the sound but the restriction concerned me. So I bought another one. The one I am using is MUCH larger and certainly larger than the flow from my blowoff, Even when I stapped an old gym sock around the end it was quieter. To say it wouldn't quiet it down is like saying a muffler does nothing.

Try it yourself and you will hear.

 

[MKSVT]

Would you put air filters at the end of your tailpipes?

I was going to do this but never did because i was told by a tech at procharger that it would do nothing for the sound. With all the responses from here i went outside and attached the largest filter i had laying around
that fit to my race valve. I wouldnt say it muffled the sound but it did distort the tone to a degree. I still consider it pointless/restrictive. The air is rushing out for a reason why anyone would put anything over it to silence and block the airflow path is beyond me. Procharger make the two different designs for a reason. You want it quite i would suggest recirculating it rather then making a contraction with an airflow restrictor and dirty sock at the end.

That's just my opinion.