Close

Results 1 to 15 of 15
  1. #1
    Join Date
    Jun 2012
    Posts
    1,177
    Rep Points
    801.6
    Mentioned
    14 Post(s)
    Rep Power
    9


    1 out of 1 members liked this post. Yes Reputation No

    Overspeed on Rear Turbo

    Hey Guys,

    Did some maintenance today and finally got an endoscope down the intakes to see what 86k miles (60k at 17.5psi) looks like. Need some advice/opinions on how bad the overspeed is at the rear turbo. Maybe @VargasTurboTech can chime in.

    Thanks!

    FRONT:

    Click here to enlarge


    Click here to enlarge


    Click here to enlarge


    Click here to enlarge


    Click here to enlarge



    REAR:

    Click here to enlarge


    Click here to enlarge


    Click here to enlarge


    Click here to enlarge


    Click here to enlarge

    I am assuming the oil on the rear turbo is from the PCV. Hoping anyway... When knocking the turbos (front and rear) with the endoscope they didn't seem to have play, but I did get them to rotate some.

    I adjusted the rear wastegate tighter by 2 turns a long time ago to get rid of some rattle. It worked, but likely it has been driven harder than the front turbo. I will need to tighten the front up.

  2. #2
    Join Date
    Aug 2012
    Location
    Hayward, CA
    Posts
    7,920
    Rep Points
    3,985.4
    Mentioned
    324 Post(s)
    Rep Power
    0


    1 out of 1 members liked this post. Yes Reputation No
    You emailed me, I have no idea what you are asking though. I do not see any evidence of overspeed, overspeed shows itself with failed turbos over time. Sticking a camera in there isn't going to tell you much besides you have no compressor wheel damage, but if you did your turbo would fail shortly after. From what I see, they look fine.

  3. #3
    Join Date
    Oct 2012
    Location
    AZ
    Posts
    666
    Rep Points
    1,745.2
    Mentioned
    17 Post(s)
    Rep Power
    18


    Yes Reputation No

  4. #4
    Join Date
    Jun 2012
    Posts
    1,177
    Rep Points
    801.6
    Mentioned
    14 Post(s)
    Rep Power
    9



    Yes Reputation No
    Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
    You emailed me, I have no idea what you are asking though. I do not see any evidence of overspeed, overspeed shows itself with failed turbos over time. Sticking a camera in there isn't going to tell you much besides you have no compressor wheel damage, but if you did your turbo would fail shortly after. From what I see, they look fine.
    Thanks for the advice. I was referring to the build up of metal on the rear turbos compressor blades. Looked like the compressor was maybe contacting the housing. Originally I stuck the camera down there because I had pumped 1.2L/min of water preturbo while doing some testing. I was concerned about impingement of which there appears to be none.

  5. #5
    Join Date
    Jun 2011
    Location
    Denmark, Copenhagen
    Posts
    577
    Rep Points
    548.1
    Mentioned
    14 Post(s)
    Rep Power
    6


    Yes Reputation No
    These turbos at 16psi is nothing, alpina b3 biturbo runs 16.5 psi stock, b3s 18 psi stock - SAME turbos!

  6. #6
    Join Date
    Oct 2012
    Location
    AZ
    Posts
    666
    Rep Points
    1,745.2
    Mentioned
    17 Post(s)
    Rep Power
    18


    Yes Reputation No
    I see no signs of compressor/housing contact. Maybe need better pics to see if it is there but I don't see signs of it.

  7. #7
    Join Date
    Jun 2012
    Posts
    1,177
    Rep Points
    801.6
    Mentioned
    14 Post(s)
    Rep Power
    9



    Yes Reputation No
    Click here to enlarge Originally Posted by lfelunden Click here to enlarge
    These turbos at 16psi is nothing, alpina b3 biturbo runs 16.5 psi stock, b3s 18 psi stock - SAME turbos!
    Yeah, I am at 17.5psi. They are basically maxed out at 18psi. You can get a little more, sure, but its going to take a lot of pwm...

  8. #8
    Join Date
    Jun 2012
    Posts
    1,177
    Rep Points
    801.6
    Mentioned
    14 Post(s)
    Rep Power
    9



    Yes Reputation No
    Click here to enlarge Originally Posted by SCGT Click here to enlarge
    I see no signs of compressor/housing contact. Maybe need better pics to see if it is there but I don't see signs of it.
    Awesome. Thanks!

  9. #9
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    119,424
    Rep Points
    32,105.2
    Mentioned
    2106 Post(s)
    Rep Power
    322


    Yes Reputation No
    I'm not sure what signs to look for regarding contact and I'm no turbo expert but does this picture not show some contact/damage?

    Click here to enlarge

    Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale
    : http://www.boostaddict.com/showthrea...r-kit-for-sale

  10. #10
    Join Date
    Oct 2012
    Location
    AZ
    Posts
    666
    Rep Points
    1,745.2
    Mentioned
    17 Post(s)
    Rep Power
    18


    3 out of 3 members liked this post. Yes Reputation No
    No. I agree there is something there though.

    Contact between the compressor wheel and the housing will tend to occur at the knee of the bend in the housing first. In other words, 1/2 way through the curve. As such, you would not be able to see it from this angle. If you WERE able to see housing/compressor rub right from the front it would be very bad, it would mean your clearances through the turbo had gone to hell, the compressor wheel would have -at best- developed a peeled back edge, your efficiency would have gone to hell and this would have shown in logs for sure, unless you're running very conservative boost. Hint: You're not. Click here to enlarge

    That aside, the artifact circled in red is not typical of the housing being even kissed by the compressor wheel. A minor kiss tends to look like a buff mark at best, or maybe some slight polishing, not the little snake bite type thing we see there. This is intuitive if you think about it. The mark shown could have been anything but I'd bet an orange soda that it wasn't from the wheel. Maybe some piece of dirt or large grain of sand made it through. Same thing for the compressor wheel. The artifact shown was likely a small foreign object. Keep in mind the size of these things means the indications shown are tiny.

    This is nothing to be concerned with. Click here to enlarge

    Click here to enlarge

    Edit: This is what < 0.003" rub did to a housing. You can see where there compressor hit, then skipped and hit again. This is typical minor rubbing/kissing. Note where it is with respect to the knee of the curve. Hope this is helpful.


    Click here to enlarge
    Last edited by SCGT; 09-23-2013 at 12:36 PM.

  11. #11
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    119,424
    Rep Points
    32,105.2
    Mentioned
    2106 Post(s)
    Rep Power
    322


    Yes Reputation No
    Click here to enlarge Originally Posted by SCGT Click here to enlarge
    That aside, the artifact circled in red is not typical of the housing being even kissed by the compressor wheel. A minor kiss tends to look like a buff mark at best, or maybe some slight polishing, not the little snake bite type thing we see there.
    Yep, that's exactly what I was referring to.

    Stage 2 or 2.5 E9X M3 S65 V8 supercharger kit for sale
    : http://www.boostaddict.com/showthrea...r-kit-for-sale

  12. #12
    Join Date
    Jun 2012
    Posts
    1,177
    Rep Points
    801.6
    Mentioned
    14 Post(s)
    Rep Power
    9



    Yes Reputation No
    Thanks for the comments. This is what I was going off of:

    Click here to enlarge

    Failed turbo:

    Click here to enlarge

  13. #13
    Join Date
    Jun 2013
    Location
    Chicago
    Posts
    7
    Rep Points
    30.0
    Mentioned
    0 Post(s)
    Rep Power
    0


    1 out of 1 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by rudypoochris Click here to enlarge

    Failed turbo:
    What you are showing with the above picture (top one) is very common with higher mileage turbos. Increasing the boost over "stock" levels can accelerate this process. This does not really cause any significant issues and I assume you are having no trouble building or maintaining boost so I wouldnt worry about it. Now the bottom picture is a whole different story...

  14. #14
    Join Date
    Jun 2012
    Posts
    1,177
    Rep Points
    801.6
    Mentioned
    14 Post(s)
    Rep Power
    9



    Yes Reputation No
    Yeah, the curling of the metal I thought was an indication that it was rubbing against the housing, but it may not be. Who knows! It will blow up eventually.

    Click here to enlarge

  15. #15
    Join Date
    Oct 2011
    Posts
    1,058
    Rep Points
    1,149.6
    Mentioned
    39 Post(s)
    Rep Power
    12


    Yes Reputation No
    What is also present in the "failed turbo" photo is obvious blade tip overtemperature, which in itself will also degrade the rotor clearance to the inlet.

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •