Tony D Posted September 6, 2009 Share Posted September 6, 2009 Likely your answer is to bleed off flow. Likely your RPM is too low to take the flow the turbo is putting out, and that is causing a surge. Cracking the BOV and letting it blow off would return stable flow to the comporessor section. Porting the hot side would only work if you are having a problem that the turbo is not able to bleed exhaust and this is causing an overspeed of the wheel. If the wategate is closed because you are calling for more boost, then the only way to eliminate sugre at that point is to bleed excess flow off the compressor side to reach the stable flow point of the compressor. It seems counter-intuitive to blow boost to make it stable, and make the turbo come on harder, but that is what you might have to do. Another issue is if you aren't flowing through the engine well. This raises the boost level higher than the surge point at lower rpms. Till engine demand matches flow capability of the turbo, minflow surge can occur at well below peak natural surge point. A centrifugal compressor can surge at ANY pressure (as you are finding out!), it's all a matter of flow. Keep it flowing, and it will stay happy. Blowing off flow is likely cheaper than making your engine able to handle the flow through the combustion process... Link to comment Share on other sites More sharing options...
90clipser Posted September 7, 2009 Share Posted September 7, 2009 Yeah, I tried the wastegate and it got worse. So I'm guessing like you mentioned at lower rpms so my demand for that kind of flow is just not there. I've been lookin into ways of getting rid of this and nothings really been helping. I was looking at some anti surge housings and I've realized how the turbobygarret page mentioned the porting of the shroud. I'm sure I could get a local machine shop to port it like the turbonetics housings. Would this help bleed of the pressure problem I'm having at lower boost levels and lower rpms? It's not like I'm getting huge amounts of surge. It's really slight. I'm just over the edge of not having any. Link to comment Share on other sites More sharing options...
ktm Posted September 10, 2009 Author Share Posted September 10, 2009 I've been lookin into ways of getting rid of this and nothings really been helping. Lighter spring on the BOV. Link to comment Share on other sites More sharing options...
90clipser Posted September 11, 2009 Share Posted September 11, 2009 I'm still running the best choice for a BOV ther is for my car, factory. But it's been garage modded which eliminated all of my throttle lift surge. I took my compressor housing to a local machine shop and had them do anti-surge porting on it. It got rid of the surge but the flow going back into my intake is upsetting my MAF... Atleast my turbos safe now. Link to comment Share on other sites More sharing options...
Tony D Posted October 31, 2009 Share Posted October 31, 2009 Found this as a 'read and comment' in my work inbox. The parts involving basic surge concepts is pretty good in explaining it. Since I don't really work with variable speed stuff (gas turbines) any longer, thought this take was interesting: http://www.documentation.emersonprocess.com/groups/public/documents/articles_articlesreprints/d350790x012.pdf The graph I normally work with, and that I mentioned above is roughly approximated in this document on Page 1 http://www.osti.gov/bridge/servlets/purl/823041-YQ0uNi/native/823041.pdf I don't expect many to read it...it's not your job. But the graph is there and you can see the axis' I was referring to and the surge line, etc... Man, I read this stuff. I'm pathetic... I should be doing something else than reading technical papers on a nice day (er...evening) like this! I feel like Gilbert... Link to comment Share on other sites More sharing options...
kiwi303 Posted October 31, 2009 Share Posted October 31, 2009 Gilbert? Dilbert maybe? Link to comment Share on other sites More sharing options...
Tony D Posted October 31, 2009 Share Posted October 31, 2009 Gilbert predates Dilbert by a good 20 years... (Gilbert Below) BEFORE ANYBODY SAY IT I KNOW I'M MORE THE "BOOGER" TYPE! (Booger Below) Admittedly I more resembled Ogre most of those formative years, with heavy Booger influences, and a dash of Gilbert in earlier years. Something changed in there to make me go from Gilbert to Ogre/Booger... I believe I will blame it on Ted Nugent. (Ogre/TonyD...no laughing...) Nugent: Link to comment Share on other sites More sharing options...
bumble zee Posted November 12, 2009 Share Posted November 12, 2009 Great job Tony. That is a great write up. Link to comment Share on other sites More sharing options...
Tony D Posted February 6, 2010 Share Posted February 6, 2010 I have run across a guy in our company's design engineering department that has a Z32 Twin Turbo. Indeed, the control technology DOES exist out there now to control the BOV as a true 'unloading valve' meaning at low flow situations (higher boost, lower rpm engine demand) the BOV opens and vents excess flow to allow the turbos to spool up in a stable portion of their map and not surge on the way up the rpm band. Big Phil seemed to be having an issue like this, and my recommendation was to try and get a boost control valve set up like this, I just didn't know if one was currently available. It is, and they are electronically adjustable to dump excess flow overboard so you can run hellacious flow turbos at lower speeds without low-flow surge, and take advantage of their better high-flow high boost characteristics 'up top' in the RPM range now. I have this guys e-mail, so I will get some details on the control system he set up on his Z32 to prevent low-flow surge on his car. He said the way the car pulls now dumping boost is FAR harder than it did when it was surging and trying to develop more horsepower lower in the RPM Range. It allows you to run a much higher boost much sooner in the RPM range without surging. Cool, huh? Link to comment Share on other sites More sharing options...
Tony D Posted December 21, 2011 Share Posted December 21, 2011 In my first post on this thread, I stated that Stonewall won't break things. Recent activities in China have led me to qualify that statement to be "INTERMITTENT and even SUSTAINED Stonewall operation generally won't break things" For the purposes of this discussion the original statement is correct. But blade tears from light wheels, wheels not shot peened and stress relieved, or simply just not robust can be damaged from prolonged, sustained Stonewall operation. In 28 years of doing Centrifugal Compressors, I've seen more blade tears this year in China than the entire prior time. And then, only with one manufacturer... I still haven't seen a stonewall damaged impeller from the first company I worked for, and they don't even worry about Stonewall operation. So there you have it. Nothing changed, but technically if you have a light wheel or impeller blade, the stresses in stonewall can excite a frequency and cause them to fail. But not especially applicable to this discussion. Link to comment Share on other sites More sharing options...
purusam Posted August 21, 2013 Share Posted August 21, 2013 Greetings from Sweden. For your information: The car is the new Mazda 6 twinturbo 175 horsepowered manual Diesel. I found this thread when i was googling around. I hope some of the members posting in this thread is still active. I have a problem. When im shiting gear this muffling fluttering whatever sound comes when change gear. My dealer says it is the wastegate doing its job. But i didnt belive it. So ihave done some reseach about the sound that are coming when i change gear But the term wastegate was wrong.? The right term is compressor surge (comp surge) So i recorded the sound from the inside when i was driving. You have to turn upp your volume very mutch to hear it. (bad phone to record with) http://speedy.sh/bFjxM/compressor-surge.mp3 http://speedy.sh/GpbzH/compressor-surge1.mp3 What do you think ? My questions to you guys is. 1: Can this compressor surge (comp surge) damage the engine ? 2: Does your vechicle make this sound (diesel) ? 3: What can be done about this issue? ? Link to comment Share on other sites More sharing options...
purusam Posted August 21, 2013 Share Posted August 21, 2013 Youtubevideo showing the sound. http://www.youtube.com/watch?v=EW4wxFr6wXA&feature=youtu.be Link to comment Share on other sites More sharing options...
BLOZ UP Posted August 22, 2013 Share Posted August 22, 2013 (edited) Is it stock? Recirculating valve. Completely normal. Can't really hear anything though. "Genuine" surge will be at certain RPMS under load, not when you shift. Weird noises when you shift are either blow off/recirculating valves or compressor stall due to flow reversion (and maybe a combination of the two). Not likely to happen on a stock vehicle. Edited August 22, 2013 by BLOZ UP Link to comment Share on other sites More sharing options...
purusam Posted August 22, 2013 Share Posted August 22, 2013 (edited) Is it stock? Recirculating valve. Completely normal. Can't really hear anything though. "Genuine" surge will be at certain RPMS under load, not when you shift. Weird noises when you shift are either blow off/recirculating valves or compressor stall due to flow reversion (and maybe a combination of the two). Not likely to happen on a stock vehicle. Yes its a stock. I have done nothing to tune it. To hear the sound in the video you have to turn upp your volume real high becouse my microphone is bad. It cant be normal that the car makes this sound ? I belive the car did not do this sound when o drove it out from the dealer first time. The sound comes on first gear when im in 2000 rpm and going to shift to see cond gear. When i let my fot od the gas and pressing down the clutch I have heard the sound on others gears but its not always there. The rattle sound always come in the first gear when shifting to second gear. The car is a diesel with twinturbo Edited August 23, 2013 by purusam Link to comment Share on other sites More sharing options...
Tony D Posted August 23, 2013 Share Posted August 23, 2013 " Weird noises when you shift are either blow off/recirculating valves or compressor stall due to flow reversion (and maybe a combination of the two). Not likely to happen on a stock vehicle." Uh..."stall due to flow reversion"? Dude, did you even READ this thread???? You just thesaurused surge... Sounds like a re circulation valve to me. The ECU may hold the bypass way open for the first xxxx km as a break-in aid, nd gradually low full boost later on. Low boost won't make the noise...but the later allowed boost might. I know nothing about the car, but that is where I would leave it. Link to comment Share on other sites More sharing options...
BLOZ UP Posted August 23, 2013 Share Posted August 23, 2013 " Weird noises when you shift are either blow off/recirculating valves or compressor stall due to flow reversion (and maybe a combination of the two). Not likely to happen on a stock vehicle." Uh..."stall due to flow reversion"? Dude, did you even READ this thread???? You just thesaurused surge... Sounds like a re circulation valve to me. The ECU may hold the bypass way open for the first xxxx km as a break-in aid, nd gradually low full boost later on. Low boost won't make the noise...but the later allowed boost might. I know nothing about the car, but that is where I would leave it. No, pretty sure I didn't use a thesaurus. What's wrong with what I said? If you are pushing air and it has no where to go from a lack of a relief valve, your compressor slows down real quick. That's what I meant by stall. Link to comment Share on other sites More sharing options...
Tony D Posted August 23, 2013 Share Posted August 23, 2013 Thesaurus Surge: stall, flow reversal, whumpies, banging the Hammer of Thor, compressor cough, scrap cough, scrap bang, wheel twister.... Using the word "stall" and "flow reversal" as if they are NOT "Genuine Surge" is hat you said wrong. Compressor stall IS Compressure SURGE! As I said, did you read this thread before posting what you did? Link to comment Share on other sites More sharing options...
BLOZ UP Posted August 23, 2013 Share Posted August 23, 2013 (edited) Thesaurus Surge: stall, flow reversal, whumpies, banging the Hammer of Thor, compressor cough, scrap cough, scrap bang, wheel twister.... Using the word "stall" and "flow reversal" as if they are NOT "Genuine Surge" is hat you said wrong. Compressor stall IS Compressure SURGE! As I said, did you read this thread before posting what you did? I was trying to differentiate between the 'surge' of the compressor flowing more than the engine can handle under WOT (or near WOT or whatever), and the 'surge' of when the engine/compressor inertia still flowing air against a closed throttle plate (I'm assuming his diesel has one). Browsing over the beginning of the thread again, I don't see what the big deal is. Edited August 23, 2013 by BLOZ UP Link to comment Share on other sites More sharing options...
purusam Posted August 24, 2013 Share Posted August 24, 2013 The fluttering sound i have is when i press down the clutch. Link to comment Share on other sites More sharing options...
Tony D Posted August 24, 2013 Share Posted August 24, 2013 (edited) They are both surge, they both are the EXACT SAME phenomenon, that is what the problem is! Please quit confusing the terms, trying to split them into two conditions which are physically identical, or applying them improperly, you aren't doing anybody any good muddying the terms up using them improperly. By your own words in your last post you don't understand what you are trying to explain. My suggestion to read was so you would understand the proper terminology and physical phenomenon you are attempting to discuss. It specifically explains the two conditions which you lay out, and WHY they are the same. The diesel noise should be a thread query in Turbo/Supercharger really, and not this one. Edited August 24, 2013 by Tony D Link to comment Share on other sites More sharing options...
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