Is my bypass valve loud?

foxbody302 · 06-21-2009, 12:10 AM

I have just a standard plastic bosch bypass valve routed back into my power pipe and that thing is loud at only 5#'s. Is this normal?

Listen in the video at 1:00-1:03

http://videos.streetfire.net/video/t...ort_197508.htm

Rich Gill · 06-21-2009, 07:00 AM

I doubt thats your bypass valve, they are typically really quiet

foxbody302 · 06-21-2009, 10:27 AM

I thought they were quiet too. I do not hear it in between shifts of anything just on a real heard pull and let off quick.

Anyways i just thought it was odd.

Woodard2589 · 06-21-2009, 01:10 PM

i cant really hear anything. can you hear it just revving it up sitting there. i had what i thought was a bad bearing or something in my s-trim but it turns out the idler pulley right beneath it was the sound as the bearing had went out and had quite a wobble to it.

foxbody302 · 06-21-2009, 03:27 PM

Quote:

Originally Posted by Woodard2589

i cant really hear anything. can you hear it just revving it up sitting there. i had what i thought was a bad bearing or something in my s-trim but it turns out the idler pulley right beneath it was the sound as the bearing had went out and had quite a wobble to it.

The noise im talking about is a rushing air sound at about 1 miniute and 1 seconds in the vid.

864svt · 06-21-2009, 03:50 PM

on my old 00GT my BPV was probably just as loud , but i was running 12psi, sounds about right though, dont think its anything to worry about

864svt · 06-21-2009, 03:51 PM

Quote:

Originally Posted by foxbody302

The noise im talking about is a rushing air sound at about 1 miniute and 1 seconds in the vid.

does it do it when your on the throttle? or off?

avexhype · 06-22-2009, 10:57 AM

mines louder

http://videos.streetfire.net/video/v...-up_636395.htm

p.s: YES thats the stock bosch BPV

foxbody302 · 06-22-2009, 04:55 PM

Quote:

Originally Posted by avexhype

mines louder

http://videos.streetfire.net/video/v...-up_636395.htm

p.s: YES thats the stock bosch BPV

Vented to the atmosphere i assume??

Also how much psi?

ESPSteeda · 06-22-2009, 05:10 PM

Quote:

Originally Posted by avexhype

mines louder

http://videos.streetfire.net/video/v...-up_636395.htm

p.s: YES thats the stock bosch BPV

I hate to tell ya bro, but what you hear is compressor surge. That little Bosch is not bleeding off enough air so your getting reverberation in the pipe. Thats the same problem that I had with mine since the day I put the system in. I added another BPV parallel to the original and it was fine for a little while. At 12PSI though your seriously overcooking that little valve and making the compressor freak out. I would upgrade. PM me if interested... I actually have two of those little Boschs for sale. I ended up going with a Vortech Mondo BPV.

kwikstang · 06-22-2009, 08:25 PM

Quote:

Originally Posted by ESPSteeda

I hate to tell ya bro, but what you hear is compressor surge. That little Bosch is not bleeding off enough air so your getting reverberation in the pipe. Thats the same problem that I had with mine since the day I put the system in. I added another BPV parallel to the original and it was fine for a little while. At 12PSI though your seriously overcooking that little valve and making the compressor freak out. I would upgrade. PM me if interested... I actually have two of those little Boschs for sale. I ended up going with a Vortech Mondo BPV.

ditto....turkey under the hood.

foxbody302 · 06-22-2009, 11:39 PM

I guess surge is possible, i just didn't think about it. It is a small blower only pushing 5 lbs i figured the bosch would keep up fine..

Beast_88_GT · 06-23-2009, 12:53 AM

Quote:

Originally Posted by ESPSteeda

I hate to tell ya bro, but what you hear is compressor surge. That little Bosch is not bleeding off enough air so your getting reverberation in the pipe. Thats the same problem that I had with mine since the day I put the system in. I added another BPV parallel to the original and it was fine for a little while. At 12PSI though your seriously overcooking that little valve and making the compressor freak out. I would upgrade. PM me if interested... I actually have two of those little Boschs for sale. I ended up going with a Vortech Mondo BPV.

I don't disagree but the end of the video seems a little weird. He isn't even high in the RPMs or under any load and he is still getting that sound... At less than 3000 RPMS I wouldn't think he would be spinning the blower near high enough to get that kind of compressor surge. Remember, vortech doesn't even suggest a bypass valve until you get above 6 psi.

I honestly don't hear anything on the original video near the 1 minute mark.

avexhype · 06-23-2009, 04:33 PM

no its vented back to the powerpipe.

its NOT compressor surge. i had it check out already by MANY professionals at big name shops (not saying that all of them are WRONG, but theres little chance). I thought it was CS also but, indeed it is my BPV.

One difference: mine has a metal insert instead of the stock plastic diaphram.

Also, i never go past -5 vacuum in that vid either so there is no boost factor pushing back on the compressor wheel. Even then, vortech doesnt specify using a BPV till above 5 psi. Still, my max boost is 9 psi at redline.

93coupee · 06-23-2009, 05:27 PM

might wanna see if the bypass valve is loose on where it hooks up at....

before i hose clamped mine inplace on the inlet and outlet of the bypass valve is was quiet... then id get into hard...and it would blow it out of the discharge side of the intake and then it was loud like yours..now thats it clamped in doesnt blow it off and its not loud...i was thinking about going with a Mondo and venting to Atmosphere so i would be loud! but i dont have enought room on my 94 anywhere... i know they make a mini verson of the mondo which i might try

Quote:

Originally Posted by avexhype

no its vented back to the powerpipe.

its NOT compressor surge. i had it check out already by MANY professionals at big name shops (not saying that all of them are WRONG, but theres little chance). I thought it was CS also but, indeed it is my BPV.

One difference: mine has a metal insert instead of the stock plastic diaphram.

Also, i never go past -5 vacuum in that vid either so there is no boost factor pushing back on the compressor wheel. Even then, vortech doesnt specify using a BPV till above 5 psi. Still, my max boost is 9 psi at redline.

ESPSteeda · 06-24-2009, 03:17 PM

Quote:

Originally Posted by avexhype

no its vented back to the powerpipe.

its NOT compressor surge. i had it check out already by MANY professionals at big name shops (not saying that all of them are WRONG, but theres little chance). I thought it was CS also but, indeed it is my BPV.

One difference: mine has a metal insert instead of the stock plastic diaphram.

Also, i never go past -5 vacuum in that vid either so there is no boost factor pushing back on the compressor wheel. Even then, vortech doesnt specify using a BPV till above 5 psi. Still, my max boost is 9 psi at redline.

I beg to differ with you (not trying to be a d1ck) but I have been fighting that exact same problem for over 2 years in my car. What Vortech says the valve should handle and what it realistically does are two TOTALLY different things. I had a single Bosch valve on my setup from the get go and I was only seeing about 6-7psi at 6000rpm. That little valve would surge on anything above 3000rpm. Even worse, if I pulled the vacuum line off, it would surge just revving it up at 2000rpm and up. The fact that you were never past 5 inHg (-5 vacuum) is irrelevant because your boost/vacuum gauge reads from the intake side behind the throttle plate. As you close the throttle, you get more vacuum on the intake side and more positive pressure pushing back on the turbine, hence the need for the bypass valve. If you are above idle on the compressor side of the throttle plate, you are building boost. Tap a boost gauge in somewhere between the throttle plate and compressor and you will see what I mean. Mine would flutter over 20psi at under 2000rpm. You either have one of two things happening. Either your vacuum line to your BPV is not working and that noise is strictly the pressure bouncing the diaphragm in the valve (compressor surge as well) or your over burdening the valve and thats compressor surge on the turbine. Either way, after two years of arguing with Vortech and adding parallel valves, and changing this to modify that, I can assure you, its not supposed to sound that way. Being that it happens at such low RPM, I am going to say option A and I would check the vacuum supply to the valve. Put a vacuum gauge on it and make sure your getting full vacuum.

Good luck

foxbody302 · 06-24-2009, 05:37 PM

I want to upgrade to a blowthrough and use a blow off. Im just not sure how that would be with no intercooler. It is kinda a short shot from the blower to the tb.

ESPSteeda · 07-01-2009, 12:36 AM

Quote:

Originally Posted by foxbody302

I want to upgrade to a blowthrough and use a blow off. Im just not sure how that would be with no intercooler. It is kinda a short shot from the blower to the tb.

You can do it. I have seen a few peoples setups that had the non intercooled pipe with the BPV. You MIGHT be able to get by with a dual BPV setup, like I had. More than likely you will still have surge. You really need a mini race or the mack daddy mondo.

foxbody302 · 07-07-2009, 12:44 PM

Quote:

Originally Posted by ESPSteeda

You can do it. I have seen a few peoples setups that had the non intercooled pipe with the BPV. You MIGHT be able to get by with a dual BPV setup, like I had. More than likely you will still have surge. You really need a mini race or the mack daddy mondo.

I might try that when i go to get another tune towards the end of the year. Supposedly the blow through is easier to tune with??

Juiced88Coupe · 07-07-2009, 06:47 PM

Here is a quick vid with my Mondo. I know that 9psi is not that much, but even with the little powerdyne on a 351, it released ALOT of air. Now with my v2 on the truck it moves quite a bit more. I also did have some small cs prior to moving to the mondo.

http://www.youtube.com/watch?v=f_feG8he7cU