Ceramic Turbine wheels

[mambastu]

What causes ceramic turbine wheels to fail when boost is increased ?

Is it due to the RPM increase or due to heat or some other reason ?

[BHDave]

If you over speed the turbo the ceramics will shit them selves after a while. You can run higher boost than recommended for short stints and get away with it.

Then they dont like too much heat either. If you have a continuous on boost run, then you can have the turbine delaminate and fall off the shaft. My rb20 turbo died on 12 psi after a cruise one night cos it was an boost constantly for 45 minutes or so.

[unwritten law]

stock intercooler??

[mambastu]

So it sounds like its RPM and heat that causes them to pop. I wondered if Water injection would help keep the wheel in one piece but if its RPM too then I guess the answers no.

[rob77]

Just heat. The higher the boost the more heat created, with the stock r33 turbo there isnt much point in taking it above 12psi as above that it only creates more heat than power and will decrease the life substantially.

[mambastu]

Just heat. The higher the boost the more heat created, with the stock r33 turbo there isnt much point in taking it above 12psi as above that it only creates more heat than power and will decrease the life substantially.

Interesting. I'm in the middle of adapting a GTR twin setup to go on my RB25 and I've heard they pop at about 1.1 bar, just wondered if I could get a little more out of them using water injection.

[rob77]

If the turbo's were brand spanking new you might be able to run 1.1bar for a little while without any problems, but seeing as most of the turbo's in our cars have covered 50,000km's+ before we got them its safe to say keep the boost to 12psi unless you want the ceramic wheels to fall off. There is no black and white no dead straight line down the middle of where you can safely run "x" boost but the most comon setting to see a good life out of the turbo is around 12psi or 0.8bar. If they are n1 turbo's which I think have steel wheels then 1.1bar is fine. As for water injection I thought that only starved off detonation?

[TTT]

the main cause is SHAFT speed.

if you increase boost, you get more power.

this is cause the turbo has to spin faster to produce this.

That is the cause of the DISTRUCTION of the EPOXY (glue) that holds the ceramic exhaust wheel to the shaft.

If you are looking at using the GTR turbo's on your rb25det, you should be able to run 1.1 bar.

this is because you have a total of 1.1bar of boost in the plenum, BUT, this is created from 2 identical turbos which are working hard enough to create 0.55bar boost each.

Yes they are smaller than the rb25det turbo, but that sort of boost is capable from those turbos.

[mambastu]

As for water injection I thought that only starved off detonation?

I'm using WI mainly for its anti-detonation properties but as I understand it it also reduces exhaust gas temperature too so I figured it might enable me to run a little more boost than the 1.1 bar maximum I've been quoted from the re-built GTR turbos I have.

the main cause is SHAFT speed.

if you increase boost, you get more power.

this is cause the turbo has to spin faster to produce this.

That is the cause of the DISTRUCTION of the EPOXY (glue) that holds the ceramic exhaust wheel to the shaft.

Oh bugger :Paranoid:

[TTT]

you have rebuilt GTR turbo's with CERAMIC exhaust wheels?

why?

[mambastu]

you have rebuilt GTR turbo's with CERAMIC exhaust wheels?

why?

Because I re-built them myself with new bearings and seals

[rev210]

it may run into the housing and shatters at high shaft speeds (beyond the facotry balance point?). By removing material from the snout this appears to allow greater boost to be run.