BOV flutter?

[Ingwe]

Ran a couple searches and couldn't find anything relating to this specific noise. Posted it here as I figured the turbo gurus would find it quicker than chit chat.

This is what i'm referring to. The noise after he lets off the gas...



I've been in quite a few factory turbo cars and none of them make this noise. A friend of mine has a Seat Leon tuned with a bigger IC and downpipe etc. and his makes the noise. When I googled it, it seems ricers love it and actually try to get the car to make the noise. Of all the vids i've seen of turbo'd mustangs on this board, i've not heard any of them make it. I just assumed it was bad purely because i've not heard factory stock cars with turbos make it.

Anyone know what causes it and if it is good, bad or just ugly (sounding)?

 

[Bobby]

The reason a factory bov doesnt make that noise is that it blows back into the intKe tube so you will never hear it. The one that you are refering to vents to atmosphere. We use one that vent to atmosphere as well. You hear it on our kits everytime you let off the gas as long as there is pressure in the pipe.

 

[CPRsm]

That sound is turbo surge, bad for the turbo.

 

[Bobby]

Is that what he is refering to or just blowing off to atmosphere. I was just refering to blowing off to atmosphere. Yes surge is bad. Anti surge compressor covers help along with an extra bov so it want back up into the turbo and surge.

 

[lito]

Any new turbo kit you could buy today for your car will be blow thru so it will have a blow off valve, it vents to atmosphere, our turbo cars are 9x% open wastegate (exhaust waste for pressure control is thrown to the atmosphere too and not thru the exhaust system and silenced) so they are really loud at boost so is hard to hear the pressure relief on the valve.

Also, most of the valves provided kits do not have trumpets so don't sound too much.

In this video at around 1:30 you can hear a turbosmart race BOV.

 

[JeremyH]

The sound is compressor surge from the bov not operating properly.

 

[BlackMustang690]

The sound is compressor surge from the bov not operating properly.

Yes +1 on this, my procharged mustang sounded like this for a about 2 months, I liked the sound but a couple of months later it went out and had to purchase a new one bov

 

[Ingwe]

Is that what he is refering to or just blowing off to atmosphere. I was just refering to blowing off to atmosphere. Yes surge is bad. Anti surge compressor covers help along with an extra bov so it want back up into the turbo and surge.

Not the blowing off to atmosphere. What I would describe as a bird-like sound starting high pitched and descending in tone in a 'flutter'. The wastegate releases excess exhaust gasses after a certain psi and the BOV releases trapped gasses between a closed throttle plate and the turbo so both should sound like a hiss (in my educationally limited guess) right?

Any new turbo kit you could buy today for your car will be blow thru so it will have a blow off valve, it vents to atmosphere, our turbo cars are 9x% open wastegate (exhaust waste for pressure control is thrown to the atmosphere too and not thru the exhaust system and silenced) so they are really loud at boost so is hard to hear the pressure relief on the valve.

Also, most of the valves provided kits do not have trumpets so don't sound too much.

In this video at around 1:30 you can hear a turbosmart race BOV.

Thanks Lito. I'm familiar with the process but I'm talking about the sounds at 1:41 and 1:44 in your video. Is that the BOV making the noise?

That sound is turbo surge, bad for the turbo.

The sound is compressor surge from the bov not operating properly.

Cars that seem to be operating well with aftermarket kits don't seem to do it (or as Lito said, maybe the wastegate is so loud that I may not be hearing it).

This is a good article I found after googling compressor surge http://www.gfb.com.au/tech/tech-articles/11-the-truth-about-compressor-surge

Don't hear it on other turbo cars like Jason's (jodadejss06gt)

Jeremy's

and several other's whose videos I couldn't find to link.

Seems most of the ricers love the noise and actively try to get their cars to make the sound!

 

[CPRsm]

Silly ricers. All you need to do is over tighten the bov spring and it'll make that noise til the compressor nut comes off lol

These you can hear a single WHOOSH, no surge





About 32 seconds in during this one here

 

[TheKurgan]

Yep that is from the gears getting yanked back an forth...not good. Needs a smaller spring or loosen it up.

 

[lito]

The sound is compressor surge from the bov not operating properly.

That is what I initially thought when I got the race port installed, welded it pre IC (stock location was on the IC exit), then got an extra set of springs for it and could not go any lower or it will open at idle, checked everything while on the dyno and sound came from the valve bouncing, no damage to the turbo that we could check, at the end I got tired of pipes, heat and melting stuff and took everything out. I could be wrong though.