.

[williamwong]

Hit a new personal best of 37.8 psi the other night! Turbo still going strong.


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Stock internals?! Stock fueling?

 

[RickyMK7R]

RE: TR-TW1003 IHX475 Turbo RMA R0457

This RMA R0457 was received on Monday 5/14/2018. Customer claimed that there’s excess of in and
out shaft play on the impeller shaft. Below are the pictures of the turbo after the tear down.

There is a large piece of the exhaust turbine blade that had broken off causing the shaft to have more
room for shifting. There are number of causes for a section of the exhaust blades to break off as shown
in the picture. Major causes could be:
1. Excess heat build-up in the exhaust side causing the metal to crack and break away.
2. Engine oil thinning out too quickly and causing excess heat build-up.
3. Overboosting causing lean condition
4. Lean conditions
5. Foreign objects getting into the exhaust housing


turbowarranty by 183dabb0820e46b49f82f2da44b58cf9, on Flickr


It is recommended to use ester based engine oil and octane booster for high boost application to
protect both the turbo and engine. For this RMA, we will warranty this turbo with a new unit as a
courtesy however we do not see defects from the turbo workmanship. Due to the damage sustained in
the exhaust blade, there will be debris in the exhaust components of the car, ie downpipe, catback etc.
We are not responsible for any further damage to any parts of the vehicle that may have caused.
We will send a new replacement turbo and provide you with tracking
We reserve the right to deny any warranty claim in the future.
You can contact us if you have any other questions.

Regards
Tomioka Racing

 

[RickyMK7R]

I'm glad I'm getting another turbo, but it seems to me that the bearing failure led to the shaft play that led to the turbine damage.



I don't know alot about turbo enginineering, but didn't think that the turbine kept the shaft in place.

 

[Hoon]

I don't know alot about turbo enginineering, but didn't think that the turbine kept the shaft in place.

It doesn't, the thrust bearing does.

That response says a lot. I'll leave it at that.

No pics of anything from inside the CHRA?

 

[RickyMK7R]

Nope no pics from inside the chra. Either way I'm just glad they're sending me another one. Although I probably won't put it back in

 

[SugarMouth]

Nope no pics from inside the chra. Either way I'm just glad they're sending me another one. Although I probably won't put it back in

Which direction you thinking now?

 

[RickyMK7R]

Staying with the is38 for now.....thinking efr but gonna let the mqb platform some more time to see what comes out

 

[dwvw]

I assume you're running upgraded map sensors is that correct Derek

Stock map sensor. Stock fuel. Had a tank of 116. Cranked up the sliders made a pass then turned back down to 30psi.


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[dwvw]

Stock internals?! Stock fueling?

Yes.


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[azuraR]

It doesn't, the thrust bearing does.

That response says a lot. I'll leave it at that.

No pics of anything from inside the CHRA?

If the blade breaks due to whatever reason then it would no longer be rotating correctly and/or not be balanced any longer which would lead to the shaft overall not rotating correctly and becoming damaged, no? Its the job of all the bushings and bearings to keep things from moving any other way but correctly.

Regardless, good to see TR holding up with their warranty work. This turbo isn't made for the largest horsepower figures too if that was the goal of Ricky's. I do agree with their reasons of possible failure, as its easy to not do even the smallest thing.

 

[MyGolfMk7]

Knock itself isn't what kills a turbo. It's the logic in what the ECU does when it retards timing. If you're at WOT and you get a 4º or a 5º timing reduction at full power enrichment, there's a decent amount of unburnt(cool) fuel going out the back. If it can kill a catalyst, it can kill a turbo.

Can is the keyword here, not will, can.

How does the rich AFR kill the turbo?

You can't see how a turbo would fail if there was suddenly a restriction in place that would cause it to work harder in order for it to spin?

If it was an externally wastegated turbo setup it would only exhibit power loss, but since the wastegate dumps into the rest of the exhaust like everything else, the turbo never gets to spin without doing a ton of extra work.

A sudden restriction, you mean instantly the exhaust flow halts?

The turbocharger doesn't "work harder" when the post turbine exhaust path becomes restricted. The pressure differential across the turbine wheel decreases, the lower expansion ratio means the compressor can't generate a high boost pressure. It doesn't just start working harder if the exhaust gas pressure differential driving it decreases.

Using the clogged cat example, yes it would build boost faster, which means the ECU would see it's target airload, open the wastegate sooner, but that exhaust is still dumping to an over restricted system that doesn't have enough volume to do it's job anymore.

No, if the cat was clogged it would not build boost faster, it would build boost slower because the pressure differential across the turbine would be decreased.

If you still can't see how a low d/p across any turbine due to restriction can lead to shaft failure, think that the amount of force being applied hasn't changed, and the energy has to go somewhere.

The restriction in the exhaust post-turbine causes the forces acting on the turbine wheel and turbo shaft to decrease.

No need to throw a bunch of shade over the internet because someone throws some ideas out there based off of their own personal experiences.

I disagree with some of the things that you are saying because they conflict with my understanding of how a turbocharger operates. If you find someone disagreeing with you difficult to deal with perhaps you should avoid public discussion forums.

 

[Diggs24]

Stock map sensor. Stock fuel. Had a tank of 116. Cranked up the sliders made a pass then turned back down to 30psi.


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I didnt know the stock sensors could read it up there.

 

[Oldschoolmk7]

Wow... Tick tock.

 

[dlau9]

I didnt know the stock sensors could read it up there.

I'm almost certain the stock MAP sensor cant reach that.

 

[oddspyke]

Question for RickyMK7R - was your tune running particularly rich when the turbo failed? I followed all the previous discussion, but none of it really fits with what the photos show. Obviously there is plenty of impact damage from bits of the turbine flying around, but the photos actually show erosion damage on a few of the blades as well. Most of my failure analysis experience is with industrial steam turbines, but it definitely looks like moisture impingement. A small amount of fuel going to the turbine won't usually hurt it as it stays in vapor form, but put enough in and it will form droplets when the pressure/temp drops across the turbine and erode the blades, especially if it's pulling timing and still adding fuel, this is a real possibility. The moisture also causes extra stress on all the bearings by adding lots of vibration, which could have led to blades contacting the housing.