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Lol I can be a bit of a slow learner at times but I was thinking more about what you said to me yesterday and the way I normally drive my car so it's probably not worth the risk for something I can easily get done.
 

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All VSR balanced now and after seeing the before vs after results I'm glad I did! I even got to do most of it myself which was great fun, although I was really cautious with the grinding and probably took 3 times longer than it should have lol. Surprised how little material needs to be ground off to make a big change in results. Also found out of all the many GTX style knock off wheels getting around these days mine happened to be one of the better ones from the KTS factory so can't complain about that.
 

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I have a picture of a turbo I was told had failed due to dust ingress. Upon looking at it that makes zero sense to me as the inducer blade tips look perfect and show no signs of the usual wearing away or chipping, especially at the outer edges where they normally start to round off.

The exducer on the other hand looks like its been getting really hot and actually looks burnt in areas where the tip speeds would be the highest and the coloured anodising has come off.

Would love to hear others thoughts on this?

Screenshot_20200213-184054.png
 

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The tip at the 9 o'clock position looks like it's missing a chunk.

Sent from my SM-G970F using Tapatalk
 

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SUI GENERIS UTE
GQ Ute 1990 Silvertop
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Discussion Starter #66
You will find thats a sign of acceleration surge or the blades cavatitating when the tip speed is excessive. Thats usually from over the top shaft rpm from not being set up correctly on a petrol. Not that common on diesel though but possible.

A note of interest anodizing is a etching process of the surface usually 10 to 20 micron depending on spec required. Because the surface has been modified with the anodizing process it does effect the structure somewhat especially the hardness and temp properties especially on the very thin blade sections. Hence why you will see that sort of damage when the very thin blade edges see surge conditions even then i have seen that sort of thing with turbos approaching choke conditions outside there operating efficiency producing higher than normal outlet temps.

Obviously that anodizing process used on that wheel is a crap quality which has damaged the alloy properties weakening the thin blade tips. Anodizing by its nature is not very good at holding colour when temps get into the 200+degree C area.

It blows me away when comp wheel design engineers allow their super high speed billet wheel to be anodized and still keep any sort of warranty of any form.
 

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Thanks for the info, confirms exactly what I was thinking. Also to add, I just saw video of it surging quite violently when accelerating, so also more evidence to confirm this theory.

Just needed another opinion to put my mind at rest. When I saw the pic and the explaining from the guy saying the turbo shops diagnosis for the damage occurring was from dust passing through the filter I couldn't stop thinking about it. It was so clear to me that there was zero signs of the typical dust damage I thought I was going crazy or blind lol
 

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SUI GENERIS UTE
GQ Ute 1990 Silvertop
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Discussion Starter #68 (Edited)
I didn't mention dust as thats just silly, dust damage is exactly like injected water damage if set up incorrectly or to much water dripping into the outside blade tips on the inducer.
Also to note What i have suggested is no theory thats fact.
 

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Found this today and it was too good not to share. Very rare to find much tech info on axial turbines;


So just how do you go about improving a turbocharger’s transient response while maintaining very high reliability and low cost? It’s evident that more than just a material change is required. We already know that lighter is better to improve transient response. In addition to mass, rotational inertia is affected by geometry; the closer the mass to the axis of rotation, the lower the inertia and the faster things will spin up.

A few other concepts related to improving a turbo’s transient response include compressor to turbine wheel matching, turbine efficiency, and Blade Speed Ratio (U/Co). U is the blade tip speed and Co (called C naught) is basically the speed of the gas flow into the turbine wheel. Co is also known as the spouting velocity and is defined as that velocity which has a kinetic energy equal to the isentropic enthalpy drop from turbine inlet stagnation pressure to the final exhaust pressure; so for our purposes, it is basically the velocity of the gas into the turbine wheel. For the commonly used radial flow turbine wheel in turbochargers, a ratio of approximately 0.7 is ideal for maximum efficiency. So we know mass, inertia, wheel matching, turbine efficiency, and Blade Speed Ratio all factor into transient response. Garrett went back to basics, reanalyzed the problem, and developed a completely new concept for a turbocharger. The concept pairs an axial flow turbine wheel to a dual-sided compressor wheel to create a turbocharger called DualBoost™ for Gasoline.


The really fundamental change is going from a radial turbine wheel to an axial turbine wheel. The axial turbine wheel address the need for improved transient response on two fronts: improved turbine efficiency at low U/Co and reduced rotational inertia. The thing we have to remember about piston engines is that the flows are pulsating and not constant. Pulsating flows leads to pulsating U/Co values and therefore varying levels of turbine efficiency.

This chart shows how the mass flow rate into the turbine inlet is a pulsating flow. Because the mass flow rate is pulsating, the exhaust velocity is also pulsating. The changing exhaust velocity changes the U/Co value at the turbine wheel. A U/Co value of 0.2 is not unusual at the start of a pulse.


Clearly turbine efficiency is a function of U/Co. Radial turbine wheels typically have a maximum efficiency at a U/Co of 0.7.


This graph shows the axial turbine’s superior efficiency versus a radial turbine at lower U/Co values. As previously mentioned, a U/Co value as low as 0.2 occurs at the beginning of an exhaust pulse. At U/Co=0.3, the turbine axial turbine wheel efficiency over a radial is about 55% versus 41%. That’s about a 34% advantage in converting exhaust energy into mechanical work to spin up the turbo faster. The axial wheel has better turbine efficiency everywhere below U/Co=0.6. This covers most of the range of U/Co the turbine wheel sees during an exhaust pulse. Therefore, the axial wheel will convert more of the energy from the exhaust flow into mechanical work than a radial wheel would.


The other major advantage of the axial turbine wheel over a radial wheel comes from geometry. A smaller diameter axial wheel can flow as much as a larger radial flow wheel. Being smaller diameter, the mass is closer to the centerline greatly reducing inertia. Remember that rotational inertia increases to the square of the distance that the mass is from the centerline, so moving the mass inward is especially important. An axial flow turbine wheel has half the rotational inertia of an equal flowing radial turbine wheel.
 

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GUII ZD30DI Wgn
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I didn't mention dust as thats just silly, dust damage is exactly like injected water damage if set up incorrectly or to much water dripping into the outside blade tips on the inducer.
Also to note What i have suggested is no theory thats fact.
Lol, here's an example for @Kiwi_dingo Mine from years ago when I got greedy with water inj on my old setup.
516161
 

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Thanks mate, that's exactly how I would have expected it to look like too. Although that's still quite minor compared to others I've seen.

I just couldn't believe a turbo shop would tell a customer complete rubbish about the damage being caused by dust ingestion. I feel sorry for all these customers who have no clue about this stuff and just take their word for it and fork out for another turbo thinking it was their own fault.
 

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GUII ZD30DI Wgn
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Thanks mate, that's exactly how I would have expected it to look like too. Although that's still quite minor compared to others I've seen.

I just couldn't believe a turbo shop would tell a customer complete rubbish about the damage being caused by dust ingestion. I feel sorry for all these customers who have no clue about this stuff and just take their word for it and fork out for another turbo thinking it was their own fault.
Abslobloodylutely.
 

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I think a lot of shops fit turbos that cannot call themselves turbo specialists.
Unfortunately these days there are far too many businesses and people who can call themselves specialists at many things with nothing more than the ability to type said statement in their advertising blurb.
 
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