Compressor Surge?
02-14-2003, 07:34 PM
#1
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Car Info: Subaru WRX Impreza 2002
Compressor Surge?
After getting my Blitz Dual Blow off valve and the Blitz SUS power intake installed I began hearing this weird spring noise whenever I don't go over 0 boost....I dunno what it is. I asked this shop and they said that whenever I don't go past 0 psi my car lets air out through the intake or some other area. I'm afraid it's air going back into my turbo....does anyone know what's wrong? My car is stock except for those 2 mods and its automatic...
02-14-2003, 11:50 PM
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I'm not sure but I know that automatics don't open the valves or whatever until it's high boost or something. This only happens when I let go of the gas. Say I go from 0-25mph and I let go I hear it. If I let go from 0-35mph it's really loud. BTW can you actually hear air going back into the turbo itself and the BOV for an automotic doesn't vent until you let fo of the gas.
Last edited by RshaoKh; 02-14-2003 at 11:55 PM.
02-15-2003, 08:29 AM
#5
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If it was leaking at idle your car would idle ruffly or even stall. I'm not sure of the sound your hearing though, if it's fluttering sound coming from the area of your turbo than it is compressor pressure surge at low rpms, I have gotten that myself with my turbo-xs BOV if I adjusted it too stiff. At high boost/high rpms people say that compressor pressure surge sounds like na shriek and is pretty nasty sounding. At low pressures on my wrx it would just make an fluttering sound(not from the BOV, the turbo) until the BOV opened up then the fluttering would go away.
If the sound is coming from your BOV area than maybe it's only opening halfway, or opening and closing an few times quickly because the boost pressure is at that level where it is building, but not enough to fully open the aftermarket BOV. That is an comon occurance with certain aftermarket BOVs, unfortunatly.
Paul
If the sound is coming from your BOV area than maybe it's only opening halfway, or opening and closing an few times quickly because the boost pressure is at that level where it is building, but not enough to fully open the aftermarket BOV. That is an comon occurance with certain aftermarket BOVs, unfortunatly.
Paul
Last edited by PaulRex; 02-15-2003 at 08:32 AM.
02-15-2003, 08:38 AM
#6
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Hmm.....I think it might be the thing with the BOV not openig all the way. Do you know what that sounds like? I have the Blitz DD Valve and the spring is as loose as it can get. The sound only happens at low rpms. Ay high rpms my BOV makes the right swoosh sound. Is the turbo on the right side of the car? When I'm in the front passenger seat I don't hear it. Oh BTW what do you mean by idle roughly? How roughly do you mean? Do you have AIM?
Last edited by RshaoKh; 02-15-2003 at 08:58 AM.
02-15-2003, 07:01 PM
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Hey, bascically I meant that if your BOV was leaking at idle, leaking air out to the atmosphere, your car would behave like it had an vacuem leak(cause it does lol), which should make it idle ruffly, like rpms going up an down sporadically, almost stalling, sounding weird etc.. OR if it leaks bad enough it could actually cause the car to just stall.
The turbo is on the left side of the engine bay(the passenger seat side), towards the back. So if your facing the intercooler from the front of your car it's to the left of it, you can't miss it, you can just follow the intake piping to it, or the intercooler piping right to it also if your not sure about it. You can only really see the compressor side, the exhuast housing of the turbo is covered with heat sheilds.
When I got compressor presure surge I would hear an fluttering sound from the turbo(not the wastegate and not the BOV), until the BOV opened up the fluttering sound would go away.(the BOV was adjusted too tightly). So i was hearing it from the right side of the engine bay when driving..
Your BOV is probaby just opening an closing an few times really fast because the pressure difference is not enough to open it fully or keep it open for an long enough time to get the "whoosh" sound. I have heard this before with some other BOVs and it sounds like what you are describing it's actually pretty common with some of them.
I using the stock one now because it's queit and doesn't cause any problems for me..
paul
The turbo is on the left side of the engine bay(the passenger seat side), towards the back. So if your facing the intercooler from the front of your car it's to the left of it, you can't miss it, you can just follow the intake piping to it, or the intercooler piping right to it also if your not sure about it. You can only really see the compressor side, the exhuast housing of the turbo is covered with heat sheilds.
When I got compressor presure surge I would hear an fluttering sound from the turbo(not the wastegate and not the BOV), until the BOV opened up the fluttering sound would go away.(the BOV was adjusted too tightly). So i was hearing it from the right side of the engine bay when driving..
Your BOV is probaby just opening an closing an few times really fast because the pressure difference is not enough to open it fully or keep it open for an long enough time to get the "whoosh" sound. I have heard this before with some other BOVs and it sounds like what you are describing it's actually pretty common with some of them.
I using the stock one now because it's queit and doesn't cause any problems for me..
paul
02-15-2003, 10:42 PM
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Hmm..I'm really scared that it's compressor surge. I heard aftermarket BOV are ONLY for bigger/aftermarket turbos....maybe the BOV wasn't designed for the stock WRX....I really don't wanna mess up my turbo. =( Could you describe compressor surge at low rpms? If I gently give my car gas it always makes that sound. It sounds painful for the turbo... I have the Blitz DD BOV. Do you know if it has anything special to prevent compressor surge? Also do you know if it's really bad if it compressor surges at low rpms only?
Last edited by RshaoKh; 02-15-2003 at 11:54 PM.
02-16-2003, 10:27 AM
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Compressor surge at low rpms isn't as bad for the turbo as high rpm/high boost situations, but I'm sure that over time it could become an factor into bending or breaking something IMO.
The only thing thats throwing me off about the sound is that your hearing it when your getting ON the gas, where I would only here the sound when getting off tha gas(when the TB closes and pressure builds up). I never owned the blitz BOV so I don;t know how it works compared to others, however aftermarlet BOV are not just for larger turbos. However the stock BOV will work fine up intil 18-19psi IIRC, and I have no problems using it running 16psi everyday.
Not for nothing, but this post would get alot more attention on NASIOC.com, I know it's whack but it seems that the board moves alot faster there and more people would get to view it. If you havn't posted it up there go ahead and see what happens IMO.
Have you tried adjusting the BOV stiffer? Or adjusting it at all?
Paul
The only thing thats throwing me off about the sound is that your hearing it when your getting ON the gas, where I would only here the sound when getting off tha gas(when the TB closes and pressure builds up). I never owned the blitz BOV so I don;t know how it works compared to others, however aftermarlet BOV are not just for larger turbos. However the stock BOV will work fine up intil 18-19psi IIRC, and I have no problems using it running 16psi everyday.
Not for nothing, but this post would get alot more attention on NASIOC.com, I know it's whack but it seems that the board moves alot faster there and more people would get to view it. If you havn't posted it up there go ahead and see what happens IMO.
Have you tried adjusting the BOV stiffer? Or adjusting it at all?
Paul
Last edited by PaulRex; 02-16-2003 at 10:29 AM.
02-16-2003, 10:35 AM
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Well it should at highrpms, but I just got quick fluttering noises from my turbo at low boost low rpms when my BOV didn't open when it should have.
It could be your wastegate flapping around, but with my car I never usually hear my wastegate however alot of people say they do. I'm using an MBC so maybe thats an factor.
If your sure that it's not your BOV making the noise then I can only assume it's either compressor surge, or the wastegate flapping, or something I havn't thought of because I'm not teh expert on this lol. Try adjusting the BOV and see if that helps.
It could be your wastegate flapping around, but with my car I never usually hear my wastegate however alot of people say they do. I'm using an MBC so maybe thats an factor.
If your sure that it's not your BOV making the noise then I can only assume it's either compressor surge, or the wastegate flapping, or something I havn't thought of because I'm not teh expert on this lol. Try adjusting the BOV and see if that helps.
02-16-2003, 10:40 AM
#12
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Hmm....what does your fluttering sound like? Mines sorta like a tight spring trying to close or something winding down. It's really deep sound. What should the wastegate sound like? Also how long does the compressor surge sound last on low rpms? Mine last about 2-3secs.
Last edited by RshaoKh; 02-16-2003 at 10:45 AM.
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