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Discussion Starter · #1 ·
Can long-term compressor surge cause catastrophic failure of a turbo?

I was so happy last night 'cos I finally got the hang of tuning with my MAP-ECU and had dialed in perfect 11.2-11.7 A/Fs. I was on my last (final check) log and was pulling through first and second when suddenly there was an almighty great POP, a sudden cloud of grey smoke behind me and complete loss of power. I got down to coasting it to a standstill and the engine sounded fine. I was only half a mile from home so decided to risk the drive. It drove ok but no boost at all. I figured I was simply going to find a blown off IC pipe. Well no sign of that but I was hearing a slight rattling noise from the turbo. Sure enough when I took off the air filter etc there was my problem. My compressor wheel (or what was left of it) was lying in the housing, shaft clean broke and no fins left at all!! My heart sank. I pulled all the plugs and thankfully no signs of damage there. I am hoping that most of the larger pieces of debris are held up at the hot side of the IC. I will do a compression test and also check the turbine wheel when I get the turbo off.

I have been living with compressor surge ever since I put this turbo on 3 years ago and have been meaning to double up on my BOV but kept on putting it off. Could this have caused this failure? There is no way a foreign object got sucked in.
 

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Silent
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are you able to check the chra bearings or the turbine seal? Is more likely that one of those seized... tho that behavior can certainly be caused by surging.
 

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Damn dude. Sorry to hear about this. Hope you get it sorted out.
 

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... Maybe a dumb question, but it's not an ebay turbo, is it?
 

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What turbo was it? It might be possible if you had a horrible surge for 3 years, but it all depends on the fatigue characteristics of the shaft. And, it also depends and how often and how hard you run that turbo,
Oh, and it doesn't have to be an Ebay turbo, my GT35R did the same thing. I really drive my car though, so I expect stuff to break frequently lol
 

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Discussion Starter · #7 ·
It's an ITS 67 mm turbo (journal bearing) and yes I drive it quite hard (18-20 psi with meth injection) and about 5K miles a year. Of course it might be a seized bearing but I guess compressor surge could have caused that. I'll check the bearings (somehow) when I get the turbo off. Whatever, when I get this fixed I will make sure I have two BOVs installed.
 

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A zone of danger.
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In for the results.

In the meantime I'd have to agree that I wouldn't expect surge to be your culprit since I've never heard of that causing complete failure, but you never know. If it's me, I'm starting with the oil feed to the CHRA. Even then you may not find the cause - could be a manufacturing defect. What BOV are you running?

On the subject, IME - the SSQV is junk when it comes to moving high volumes of air. The billet 71 on my red car would turkey call from here to Thanksgiving at anything over 18psi. But it did do a good job with the low pressure stuff, where the 'bigger' BOV's (say Tial) are a little lazy to open. The Blitz my car has now does ok, surges a little, but my T72 has ZERO shaft play. My ideal setup would be an SSQV (no squeaker) + a Tial for the big end.
 

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Discussion Starter · #9 ·
In for the results.

In the meantime I'd have to agree that I wouldn't expect surge to be your culprit since I've never heard of that causing complete failure, but you never know. If it's me, I'm starting with the oil feed to the CHRA. Even then you may not find the cause - could be a manufacturing defect. What BOV are you running?

On the subject, IME - the SSQV is junk when it comes to moving high volumes of air. The billet 71 on my red car would turkey call from here to Thanksgiving at anything over 18psi. But it did do a good job with the low pressure stuff, where the 'bigger' BOV's (say Tial) are a little lazy to open. The Blitz my car has now does ok, surges a little, but my T72 has ZERO shaft play. My ideal setup would be an SSQV (no squeaker) + a Tial for the big end.
Thanks for the advice. My current BOV is a Greddy RS.

Re. the turbo, I will report back with what I find when I take it off. I have been in contact with the guys at Comp Turbo and it's possible that it could be rebuilt with all the nice new fancy stuff (ceramic bearings, billet wheel) for considerably less than a new turbo. They would rework my current compressor housing up to anywhere between 68 and 74 mm depending on what I want. I guess they can do all this without the need for water cooling or maybe this is part of the rebuild as well? I forgot to ask.
 

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I have the SSQV, and it's doing a fine job. I noticed the size of the vacuum hose makes a big difference, which makes a lot of sense.
BTW, 5K a year isn't that much, try 80 miles A DAY while hitting the 20-25 PSI mark frequently HAHAHAh
I would check the bearings, and where the oil flows. Look for any obstruction/ dirt. Do you let your car cool down after driving?
 

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There are few things worse for a turbo than surge. You probably wore the thrust bearing out to the point that you got wheel to housing contact. Once that happens...Kableweee.

Daniel
 

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Discussion Starter · #13 ·
Are you referring to REAL compressor surge as in the surge line on a compressor map or what everyone on youtube thinks compressor surge is?
I'm talking about a fluttering noise that occured whenever I let the throttle off in boost. Audible at 5 psi to pretty damn loud at 20 psi.
 

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I'm talking about a fluttering noise that occured whenever I let the throttle off in boost. Audible at 5 psi to pretty damn loud at 20 psi.
A number of UK forums (mkivsupra.net and gtr.co.uk) are not using a BOV on their single/stock turbo cars without affecting the turbo...some have had the intercooler fall apart (due to the abrupt pressure build-up) when there's nowhere for the air to go.

I'd have to say the thrust bearing in this case as well :).
 

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I'm talking about a fluttering noise that occured whenever I let the throttle off in boost. Audible at 5 psi to pretty damn loud at 20 psi.
That would definitely not kill your turbo. Surge from throttle modulation is much less damaging than the compressor surge during acceleration (anti-surge housings work to prevent this by bleeding some of the induced air back out of the housing which is redirected back into the inducer).

I would lean more towards oil starvation. I've seen this occur to the point of the turbo seizing and in extreme conditions, snapping the nut on the compressor wheel snapping off and chewing up the wheel.

Reid
 

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Discussion Starter · #16 ·
That would definitely not kill your turbo. Surge from throttle modulation is much less damaging than the compressor surge during acceleration (anti-surge housings work to prevent this by bleeding some of the induced air back out of the housing which is redirected back into the inducer).

I would lean more towards oil starvation. I've seen this occur to the point of the turbo seizing and in extreme conditions, snapping the nut on the compressor wheel snapping off and chewing up the wheel.

Reid
Interesting Reid...and a bit concerning. I want to make sure this doesn't happen again when I replace the turbo, so would like to check and rule out as many things as possible inc oil starvation. In this regard, last night, I unscrewed the oil feed and turned the engine over (plugs removed) to check supply. Oil came through nicely. Is there anything else I should check to rule oil starvation out? I guess I could hook it up again and check the drain side?

Your contention that compressor surge (apparently a more accurate term is 'compressor stall') would not damage (i.e., eventually kill) a turbo is a bit difficult to accept. Surely it stands to reason that sudden and huge backpressure on a compressor wheel that's rotating at more than 100K/min (or whatever) and forcing it to reverse would put tremendous stress on the wheel, shaft and bearings?

There seem to be two diametrically opposed schools of thought on this issue. One is that compressor stall is a definite turbo killer and the other is that it is not a worry at all. With everthing we know about turbos and engineering technology, I find this very surprising. Right now I guess I just don't know what to believe but logic would suggest to me that it can only be harmful.
 

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from every book that i have ever read about turbo and related topics, surge can and will damage a turbo to the point of failure.....eventually.
 

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also, keep in mind that compressor surge happens when the turbo's compressor is "asked" to produce a greater pressure ratio than it can sustain at a given volume of flow. essentially the compressor wheel cavitates and unloads the turbine, and a spike in turbo rpms occurs.
compressor stall is where the sudden pressure of a closing throttle returns back through the compressor wheel, which reduces its speed quicker than normal and can lead to premature failure.
 

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Discussion Starter · #19 ·
Well, here are the findings. Turned the engine over and oil came through the turbo and out the drain end with no problem. Took the turbo off and turbine span freely with no hint of binding up. There was some lateral movement of the turbine shaft but no more than usual I'd say. I could see little evidence of bearing failure.
The shaft on this turbo is only 6 mm in diameter. Its an ITS turbo so I expect this is not atypical. With the torsional stresses it has to withstand this seems really thin to me. My gut feeling is that sustained stress from compressor surge (stall) caused this shaft to eventually give up the ghost.
 

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Silent
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Interesting Reid...and a bit concerning. I want to make sure this doesn't happen again when I replace the turbo, so would like to check and rule out as many things as possible inc oil starvation. In this regard, last night, I unscrewed the oil feed and turned the engine over (plugs removed) to check supply. Oil came through nicely. Is there anything else I should check to rule oil starvation out? I guess I could hook it up again and check the drain side?

Your contention that compressor surge (apparently a more accurate term is 'compressor stall') would not damage (i.e., eventually kill) a turbo is a bit difficult to accept. Surely it stands to reason that sudden and huge backpressure on a compressor wheel that's rotating at more than 100K/min (or whatever) and forcing it to reverse would put tremendous stress on the wheel, shaft and bearings?

There seem to be two diametrically opposed schools of thought on this issue. One is that compressor stall is a definite turbo killer and the other is that it is not a worry at all. With everthing we know about turbos and engineering technology, I find this very surprising. Right now I guess I just don't know what to believe but logic would suggest to me that it can only be harmful.
His point is that there is no load on the shaft when its surging between shifts. What can kill a turbo in seconds is getting the turbo surging while you're still on the throttle.
 
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