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Kevin 1G Drummer
10-05-2010, 07:53 PM
The noise you're hearing when letting off the throttle in low throttle situations is BOV flutter, not compressor surge. The two sound completely different and happen at different times.
Tachyon
10-05-2010, 08:04 PM
The noise you're hearing when letting off the throttle in low throttle situations is BOV flutter, not compressor surge. The two sound completely different and happen at different times.

So the noise in this video: http://www.youtube.com/watch?v=LZUbo_mNDZM is in fact flutter rather than surge? I've seen videos with nearly the same noise be labeled as both. That, coupled with the cro-magnon IQ of the average youtube car video poster, has left me just a bit confused. :lol:
Shane@DBPerformance
10-05-2010, 08:10 PM
Straight 30 weight is kinda weird, but probably not the problem.

I could see all the oil pressure you would have causing it to burn oil or push oil into the intake/exhaust housings, but I am not sure how too much pressure could cause shaft play. Shaft play would normally be caused by normal wear over time, bad build, or running the turbo at too many RPMs too much. Your oil pressure to the turbo is probably crazy though. Mitsu turbos don't require as much oil and can usually work off of the head(like they do stock on a DSM or Evo). Oil pressure with no balance shafts would be much higher and then at the oil filter housing versus the head would be 2-3 times higher.
Halon
10-05-2010, 08:12 PM
One other random thought. If you had some big boost leaks that you've never checked for or diagnosed, you may be pushing the turbo at much higher RPM's as Shane had said, which may have caused quicker wear n tear. Just a thought.
Shane@DBPerformance
10-05-2010, 08:12 PM
So the noise in this video: http://www.youtube.com/watch?v=LZUbo_mNDZM is in fact flutter rather than surge? I've seen videos with nearly the same noise be labeled as both. That, coupled with the cro-magnon IQ of the average youtube car video poster, has left me just a bit confused. :lol:

That is just his BOV. It is happening when he lets off the throttle. Real compressor surge happens during spoolup.
Matt D.
10-05-2010, 08:35 PM
Compressor surge

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Tachyon
10-06-2010, 09:38 AM
Thanks for the video, Matt; I am most certainly not having compressor surge.


One other random thought. If you had some big boost leaks that you've never checked for or diagnosed, you may be pushing the turbo at much higher RPM's as Shane had said, which may have caused quicker wear n tear. Just a thought.

That's a very good point. The car's been running so well I never did a leak check after I swapped the turbos. I will do that before firing up the next one.

Based on the information everybody has kindly provided, I do believe my best choice at this juncture is to purchase a different turbo and run oil from the head if it's Mitsu framed.
sleepydsm
10-06-2010, 02:29 PM
As said above:

Balance shafts removed, really raises your oil pressure at the OFH. I would either get some sort or restrictor, or just feed from the head as the mitsu turbos were designed for.
Goat Blower
10-06-2010, 02:41 PM
Porting the OFH orifice helps too.
CarPsyco84
10-06-2010, 05:33 PM
or get a T put a 10 dollar Oreilly oil pressure gauge on the T to the turbo and check the oil pressure... you could just run a restrictor in your oil pressure line to the turbo and you could get the same result... Just a matter of what you would rather do. Personally on a mitsu turbo I would rather just run it from the head, but this is the other option.