Compressor surge B.o.v?

[whiteDSM]

Hey, need some help. Was wondering if i was getting a compressor surge with my B.o.v, this b.o.v is aftermarket not sure what kind ( did not put it on myself). But this b.o.v is big , its releases pressure at about 3.5 or 4000 rpms but after that i will release pressure and then it sounds like a flutter from the b.o.v.

 

[1992GSX]

Sounds like nothing's wrong.....

 

[92EagleAWD]

Prob an HKS SSQV. its supposed to do that, when you let off the gas pedal that is.

 

[knochgoon24]

Does it look like this (either silver or black)?

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Mine does the same thing.

 

[DeadsEvolution1]

Same here with the HKS SSQV. It makes a fluttering sound

 

[Boost_Addict_88]

If its tha GReddy BOV, then there is a problem. I have tha Type RS (blue), and to fix my issue, I did tha single spring mod. Its easy to do. Remove tha 6(?) allen screws from tha top and pull it off. There's 2 springs inside. Pull out tha smaller spring (located inside bigger spring) and put it back together. Finally, adjust tha hard/soft screw. For reference, mine is almost all tha way down (hard).

If you have an HKS SSQV, then yes, it sounds normal.

 

[2gGSX]

Prob an HKS SSQV. its supposed to do that, when you let off the gas pedal that is.

It's not supposed to flutter--that's called compressor surge. BOV fluttering is most commonly caused by slow response. Do you have anything T'd into the vacuum line to the BOV? They really need a dedicated vacuum line from the manifold.

 

[knochgoon24]

I have yet to hear of someone running an HKS SSQV that doesn't have it flutter under low boost.

And yes, my vacuum line is a dedicated line running from the manifold BOV port to the BOV with the shortest amount of line possible.

 

[whiteDSM]

Does it look like this (either silver or black)?

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Mine does the same thing.

no, definatley not a hks. it's really long lookng unlike the hks

 

[goodhart]

It's not supposed to flutter--that's called compressor surge. BOV fluttering is most commonly caused by slow response. Do you have anything T'd into the vacuum line to the BOV? They really need a dedicated vacuum line from the manifold.

The amount of misinformation from members on this site is amazing. If you are going to make posts, then at least make sure what you are saying is legit.

Real compressor surge happens during spoolup/high boost, not when you let off of the gas. The surge noise in that video is caused by the BOV not letting all the air out in 1 smooth blow. Too tight of a BOV opening and closing over and over might not be the best thing for the turbo, if the air is actually backing up that far, but it isn't real compressor surge and the kind that ported/anit-surge compressor covers are for. People call this noise BOV surge/flutter or "internet surge" because most people on the internet don't know what real compressor surge actually is.

Compressor surge happens when the turbo is flowing A LOT of air and the motor can't actually ingest all that air. A turbo makes boost inside the compressor housing, it isn't like a roots blower/positive displacement blower that works by stacking air in the intake manifold. When air starts stacking up on a turbo car and gets stacked all the way back to the compressor housing, then surge happens. The stacked air starts stopping the spinning compressor wheel or trys to turn it backwards. When you try to stop a compressor wheel going 80,000RPMs, bad things happen.

Compressor surge is common on 2.0l motors with the 61mm turbos. The 2.0l spools the turbo to high boost levels too fast and makes more air than the motor can take in. You can try to get rid of surge by going to a larger exhaust housing/wheel, to make the turbo spool up slower. You can get bigger cams, bigger intake manifold, port the head, to try to be able to take in more air. You can goto a bigger displacement motor that can take in more air each stroke.

A ported shroud/anti-surge cover has passage ways for the backing up air to come back out the front of compressor housing and into your intake pipe to try to avoid reverse flow pressure waves from causing surge.

Basically you can't have your cake and eat it too. If you spool a big turbo too fast you get surge.

When most people experience this "flutter" is usually when they let off of the gas slowly and the BOV doesn't let off all of the pressure in one blow.

Just remember, compressor surge only happens DURING SPOOL UP.

 

[2gGSX]

The amount of misinformation from members on this site is amazing. If you are going to make posts, then at least make sure what you are saying is legit.

Just remember, compressor surge only happens DURING SPOOL UP.

Excuse me? Just what do you think compressor surge actually is? Let's call it by it's real name: compressor stalling.

When the BOV "surges" and can't release the intake charge in time, the result is the intake charge pressure wave slamming back into the compressor, causing surge/stalling.

Please stop spreading misinformation in giant bold letters.

 

[goodhart]

Excuse me? Just what do you think compressor surge actually is? Let's call it by it's real name: compressor stalling.

When the BOV "surges" and can't release the intake charge in time, the result is the intake charge pressure wave slamming back into the compressor, causing surge/stalling.

Please stop spreading misinformation in giant bold letters.

You my friend are the one spreading misinformation. The original poster of that statement, ecoli (Shane Ziegler of DB Performance) has more than likely forgot more shit about DSM's than you will ever know. After all he did tune Brent Rau's car

 

[2gGSX]

Feel free to remove your BOV and drive without it for a while.

 

[goodhart]

Feel free to call Shane and tell him he doesn't know what he's talking about.

 

[LUVMY97GSX]

I actually just had a question on my car about this topic. A guy I know is running 29 psi and has his greddy type-s turned all the way hard. I turned my type-s all the way hard and it flutters even at full boost. I've heard this is bad for the turbo even though the stock bov location is pretty far from the compressor housing? My car is completely bone stock other than the type-s. Should I turn the adjuster softer to save my turbo? Or is it not that big of a deal?

 

[LandoAWD]

The semantic argument can stop now. A BOV/CBV that doesn't release in a timely fashion can cause turbo damage...like surge.

 

[goodhart]

Feel free to remove your BOV and drive without it for a while.

I never said the flutter wouldn't harm the turbo, all I gave was an accurate description of true compressor surge.

 

[JEFFREYCASTGSX]

TRUE compressor surge happens whens your riding the surge line, you know the lower part of a map,this happens under boost(and basically WOT). Bov flutter happens when your bov cannot release all the air out under NORMAL(cruise) conditions, this type will cause very little(if any) damage to a turbo.

 

[DSM AWD TSI]

I actually just had a question on my car about this topic. A guy I know is running 29 psi and has his greddy type-s turned all the way hard. I turned my type-s all the way hard and it flutters even at full boost. I've heard this is bad for the turbo even though the stock bov location is pretty far from the compressor housing? My car is completely bone stock other than the type-s. Should I turn the adjuster softer to save my turbo? Or is it not that big of a deal?

That guy you know probably had to turn his bov all the way hard so that it wouldn't leak boost at 29 PSI, and he probably gets flutter at lower boost. Flutter is bad (wears out your turbo much faster than normal) and the higher the PSI at which the flutter happens the worse. Ideally, you want zero flutter from 0.1 PSI to your max PSI. So, to answer your question, yes you should adjust your BOV softer to save your turbo. Make sure it opens at any PSI when you let off the gas and that it doesn't leak at your max boost. The type S has two ports for hoses, the top one goes to your intake manifold and the bottom one goes to your j-pipe or intercooler pipe somewhere near your turbo (that one helps it open when there is little boost).

 

[tkelly27]

Surge also happens when you don't have a blow off valve. There is no "true surge" there is only points on the other side of the surge line on the compressor map. Here is what one looks like
http://www.mygen.com/users/dbruce/m...Compressor Maps_files/280z_flow_on_T04e51.gif
You can see how 0 flow and just about any boost is on the left side of every turbochargers surge line. This can also happen when the flow is not enough for a given amount of boost and can happen at any time the compressor is making boost, spool up, or otherwise. This can even happen if a blow off valve is too small to vent enough pressure fast enough.

Surge while under operating conditions can be potentially worse because there is still exhaust energy driving the turbine. ANY surge will mess up your turbo, no matter where it happens.

Bov flutter can occur when the bov has vented enough pressure in the intake tract to allow the valve to re-seat itself. The turbo still has enough kinetic energy to create enough pressure in the intake tract to reopen the valve, and on and on. The HKS style can transition between the small valve and the big valve making a weird flutter noise. In my experience it's distinctly different than surge.

Certain valves design will limit them to blowing off a certain boost level, then shutting. If you have the spring set too high in a turboxs valve (say... to keep it closed during idle to not leak metered air) it will give you surge at lower boost level.

WhiteDSM, what valve are you running? That will help us determine where to go next.
Does it look more like this?
http://www.clubrsx.com/graphics/00000001/TXS-BOV-H-RFL.jpg
or take a picture.

 

[whiteDSM]

Surge also happens when you don't have a blow off valve. There is no "true surge" there is only points on the other side of the surge line on the compressor map. Here is what one looks like
http://www.mygen.com/users/dbruce/m...Compressor Maps_files/280z_flow_on_T04e51.gif
You can see how 0 flow and just about any boost is on the left side of every turbochargers surge line. This can also happen when the flow is not enough for a given amount of boost and can happen at any time the compressor is making boost, spool up, or otherwise. This can even happen if a blow off valve is too small to vent enough pressure fast enough.

Surge while under operating conditions can be potentially worse because there is still exhaust energy driving the turbine. ANY surge will mess up your turbo, no matter where it happens.

Bov flutter can occur when the bov has vented enough pressure in the intake tract to allow the valve to re-seat itself. The turbo still has enough kinetic energy to create enough pressure in the intake tract to reopen the valve, and on and on. The HKS style can transition between the small valve and the big valve making a weird flutter noise. In my experience it's distinctly different than surge.

Certain valves design will limit them to blowing off a certain boost level, then shutting. If you have the spring set too high in a turboxs valve (say... to keep it closed during idle to not leak metered air) it will give you surge at lower boost level.

WhiteDSM, what valve are you running? That will help us determine where to go next.
Does it look more like this?
http://www.clubrsx.com/graphics/00000001/TXS-BOV-H-RFL.jpg
or take a picture.

It is a TurboXS.I am only running stock boost in which i dont have a boost controller anymore, so it is only running stock 7lbs.

 

[whiteDSM]

So, This shouldn't flutter?