Midwest Turbo - What is up?

[TwIzTeD_3kGt]

What doesn't make sense is MTC 19Ts performed better with the same HL 12 blade backside vs your turbos and the torque didn't drop off like a rock from 400AWTQ at 3900 rpms to 270AWTQ at 6400 rpms. That makes no sense other than there being a tuning or motor error. Torque should not drop off that sharp. Hell, put any 19T no matter who makes it up against that dyno and it will beat the pants off it so hard. With my setup I know there was plenty of power there even at redline it wanted more and more. That wasn't all because of the 9 blade turbine either. I'm curious what your dyno looks like on different turbos and hopefully it all goes very well since you've sunk too much money in the car already for it not to perform very well especially since we have plenty of results on the turbos you'll be running.

IPS 19T L wheels 415awtq@3900rpm to 350awtq@6400rpm

I'd have to agree, that's a pretty big drop.

[TurboSinceBirth]

A bit nervous about the events with these things, but I will be installing tomorrow/Sunday. There are a lot of loose ends to tie up with the other things installed, and break in mileage for the engine/clutch. Hoping to start tuning, and a trip to the dyno within a couple weeks.

You'll be fine Coop. I plan to get some VD numbers when I get the turbos back and installed. I'll be putting in a bigger BOV this time so the turbos don't come apart on high boost shifts. I don't think you have anytthing to worry about.

[CoopKill]

You are getting them back as they were before???

[TurboSinceBirth]

You are getting them back as they were before???

Well, not exactly. The 9 blade wheel MTC used isn't available because it was the only production one and I don't think MTC is interested in finding another shop to make it. Kinugawa makes a 9 blade TD04 HL turbine wheel although I'm still hesitant about their quality. That is an option if I want a 9 blade turbine wheel. I'm on the fence though and may go with the 12 blade even though I much prefer the 9 for performance. The turbos can be fixed but I don't know the damage yet.

[TwIzTeD_3kGt]

You'll be fine Coop. I plan to get some VD numbers when I get the turbos back and installed. I'll be putting in a bigger BOV this time so the turbos don't come apart on high boost shifts. I don't think you have anytthing to worry about.

WUT? What BOV were you running?

[keo92stealth]

Hmmm sounds like Mr. Ninja wants to upgrade snails ..

[NOMIEZVR4]

You'll be fine Coop. I plan to get some VD numbers when I get the turbos back and installed. I'll be putting in a bigger BOV this time so the turbos don't come apart on high boost shifts. I don't think you have anytthing to worry about.

Where did that theory come from?

[TurboSinceBirth]

WUT? What BOV were you running?

Greddy RS. I knew some people on other platforms said it had to be adjusted tight to work with higher boost but some said it had problems surging also. I never heard anything and ran it for months at 28 psi. I planned to change it to a Tial but I guess got too comfortable with changing something that wasn't broke.

Where did that theory come from?

It's about the only reasonable explanation I can come up with. I was talking to my friend that was in the car with me and he said the puff of smoke was during the 3 to 4 shift. I'm guessing what happened is that the BOV couldn't release enough volume quick enough, the air surged back against the compressor wheel, it stalled the compressor wheel enough to tighten up the compressor nut enough that the shaft snapped, and then the turbo catastrophically failed. It's obvious that the compressor nut spun off the turbo and being a left handed thread it wouldn't have done it by itself. There had to be some force acting against it so I think going from 28.8 psi 160-180k rpms and then letting off for the shift the turbo changed quite a few rpms with the BOV not helping either. In the pics you can clearly see the grooves in the compressor wheel where the nut sat.

Since Dan deleted the Devastator thread for PR reasons probably here's the pics again.

[TurboSinceBirth]

A member here also did some testing on a 9b turbo. The shaft was torqued to 40 in/lbs. At 110 in/lbs it snapped. He tried it with loctite also which increased the snapping torque another 15 in/lbs. Multiple turbo rebuilders said anything above 50 in/lbs is overtorqued and will cause the shaft to break. You can easily see that the compressor wheel stalling some due to the BOV not able to release the air quick enough or enough volume could result in the nut tightening itself. It wouldn't take much to cause a failure. That's the only logical explanation I can come up with. Had it been during a pull I'm sure there would have been something else going on but it was during the shift the turbo took a crap.

[RealMcCoy]

Hmmm sounds like Mr. Ninja wants to upgrade snails ..

That's funny...

Sounds more like he's looking for a reliable supplier of upgraded TD04's for his customers...

You'll be fine Coop. I plan to get some VD numbers when I get the turbos back and installed. I'll be putting in a bigger BOV this time so the turbos don't come apart on high boost shifts. I don't think you have anytthing to worry about.

That is as good a theory as any out there... It's pretty obvious SOMETHING caused the compressor wheel to spin on the shaft.

A member here also did some testing on a 9b turbo. The shaft was torqued to 40 in/lbs. At 110 in/lbs it snapped. He tried it with loctite also which increased the snapping torque another 15 in/lbs. Multiple turbo rebuilders said anything above 50 in/lbs is overtorqued and will cause the shaft to break. You can easily see that the compressor wheel stalling some due to the BOV not able to release the air quick enough or enough volume could result in the nut tightening itself. It wouldn't take much to cause a failure. That's the only logical explanation I can come up with. Had it been during a pull I'm sure there would have been something else going on but it was during the shift the turbo took a crap.

Being as I'm the one that did the testing, I'll clarify what I did... I sacrificed a couple of old 9B shafts and wheels to overtorque testing.

I assembled the first one with no locktite on the nut, torqued to 40 inch/lbs, and clamped the compressor wheel in the vise. I then began to apply torque from the turbine end. I found the the wheel and the flanged nut were locked by friction, and they moved together as a unit. There seemed to be little resistance to increased torque, as I was able to get it to move with under 50 inch lbs. I continued to torque it in 10 in/lb increments until the shaft failed at 100 in/lbs.(it didn't actually snap until 110, but it felt a little stretchy getting to 100, so I'm calling that the failure point)

I repeated the above with loctite on the nut, and got basically the same results with the only difference being the breakaway torque was increased by 15in/lbs. (which is a pretty significant increase of 37%) Those results may even be increased by careful and proper prep, and use of activator on the loctite.

What I would "like" to see built into the design of these huge billet wheels, is an interference fit on the shaft... It would make assembly and disassembly a bit more tedious, as you would have to warm the wheel up to install/remove, but it would positively prevent any movement of the wheels once installed and torqued.

Even if you don't break the shaft, any movement at all is going to reclock the wheels in relation to each other, and potentially create an unbalance condition. It seems pretty obvious that it's scenario that should be avoided...