That's not what I want to hear... But yes, the winding down does make the turbo suspect.

I haven't driven the car enough to have the issue worsen, but I would imagine that a bent shaft would result in a violent vibration that would very quickly destroy the turbo, no?


I would like to take back what I said about the equal sound volume at various RPMs... I drove the car some tonight and played with it a bit. The sound is correlated to air-flow. Maintaining a particular boost level while the car accelerates shows this. Carrying say 0 PSI from 2k RPM to 7k RPM, the volume/loudness of the sound grows significantly, and the volume is comparable to higher boost levels at lower RPMs.

I picked up a pipe and will test the intercooler replacement tomorrow, as well as a new air filter. I'll also talk to the turbo rebuilder some more and find out what their testing procedures are and if they would have caught a bent shaft.

Interesting. I had a noise exactly like this on a 2560 and was about to have the CHRA exchanged. I know this is no help to your issue but the noise ended up going away on its own.

did they replace the turbine? sorry I haven't really read. If you just replaced the compressor wheel, I suspect the shaft is still bent, and the new compressor blades are rubbing on the housing...

Small update:

Talked with the turbo shop. They do not bench test the turbos, but they do fully balance the shaft assembly. They said, and I completely agree, if it was unbalanced the turbo would have violently destroyed itself already.

Still waiting on the FedEx truck to deliver the air filter so I can knock that one off my list. I have a perfect piece of ABS in-hand and will install right after work tonight to cross the intercooler off the list as well.


Weird. How long did it last?

They did not replace the turbine. It was in perfect shape. This rebuilt turbo has already been off the car once and been inspected thoroughly. No rubbing, no visible issues, spins like its brand new.

It lasted for about a month and I didn't have the funds to do anything about it so I kinda left it alone while I cried myself to sleep every night lol

Even after talking to ATPturbo and garrett they thought it needed a CHRA. After shutting off the car you could hear it whining as it came to a stop.

I ran a turbo with FOD for a few weeks. the shaft was bent so the turbine was rubbing the heat shield, and a few fins were bent.

nothing was "violently destroyed"

i even ran it on a dyno where it made 30hp less than it should have and boost threshold was significantly higher than normal.


I've also run a great number of Frankensteined trubos...the only thing that exploded were my pants from all the boost

In for final solution. Hope you can get it sorted soon, Steven.

I have no good news and no bad news.

• Replaced air filter with a new AEM 21-2127DK and made zero difference to the sound.
• Temporarily removed intercooler and replaced with a 22.5" long ABS pipe. Made zero difference to the sound.

This completes my list of things to check. Going to button up the reinstallation of the intercooler tomorrow morning and do one last 12PSI boost leak test to ensure no leaks. I have no idea what I should look at next.

I am leaning towards getting the car prepped for the last AutoX of the year on Sunday and run the **** out of it. It the turbo dies, it dies. And it's on the turbo shop.


Hmm. There is certainly no whine anywhere close to idle... It would be nice if this just went away.

Okay, well then bent shaft is still a possibility then.

If it were me I'd probably run it

Thought I would give you guys a small update:
I autocrossed the Miata on Sunday and dual drove it, so it ran 16 back to back runs. Whining is neither any worse nor any better after the event.

I'm thinking about autocrossing again this Saturday and keep running it hard. It doesn't seem to be causing any issues, and I've looked at everything I could think of and everything you guys have suggested. The car is getting a new engine for next year, so the next time the turbo is out I will try to see how true the shaft is.

If you guys think of anything else, please let me know.

Thanks!

double post

Is it possible you live in the same 'hood as Bubb Rubb?