"Some Nissan turbochargers use ceramic turbine wheels - what are their advantages and limitations?
Ceramic turbines are wonderful. We've used them in Caterpillar engines and Detroit engines and they're very heat resistant materials, they're light and very responsive - but they don't like foreign objects. You've only got to have the engine tuned once on the dynamometer a little bit lean - it'll drop a bit of spark plug electrode and it's a bit like a puff of talcum powder out the exhaust. And then you don't have a turbine wheel any more. Even if you're pulling one of these turbos apart and you knock the head of the wheel, they will actually break.
The other thing that happens if they are drastically over-sped - and I mean fairly drastically - the head joint will let go at the back of the turbine wheel. It's not necessarily the turbine wheel that goes, but the assembly to the shaft. The OE has designed it to suit their application. They don't want you to go from 9 psi to 15 psi, because it's designed to be at maximum efficiency at 9 psi. Turn it up to 15 psi and the turbine speed has probably gone up 40 percent - the head of the wheel has never been designed to spin at those revolutions.
With some of them you can get away with lots of extra boost before you run into turbo problems - but it's model specific. We've not seen too many problems with basic modifications like an exhaust, air cleaner and a very mild boost increase. When you're chasing the horsepower that's available, though, that is when turbine wheel heads drop off - or if you're using the car for competition use. Over time - like in an endurance race - it'll get to the point where it fatigues.
Sometimes, with hand fabricated exhaust manifolds or even cast manifolds, if there's a little bit of welding dag or casting dag left in it - again - you might end up with no turbine wheel.
So they're generally very tough, very reliable items but they're not happy about impacts. I guess you could say they're an excellent fair weather sailer - when everything's perfect, they're wonderful. But they're not drastically good with foreign object damage."
That piece I posted was from the Autospeed article. I only posted that part as it seemed relevant to the Skyline.
It really just confirmed what most people think about ceramics, that they are good to a point but do not take overstressing very well. I remember Sean Morris (Motorex) posting a while back that det can destroy ceramics by way of shock waves and all this makes sense too.
What do you all think the max boost should be set on the standard ceramic turbos, in particular for the R33 ?
What sort of shaft speed could the stockers handle before they go kabooom !!!!
I currently have mine set on max 1.0 bar but will be winding it up & tuning it to 1.1 bar within the weeks end.
I guess if I blow them it will give me an excuse to get those 2540's even quicker !!
Joss 1.75 BAR BOOST !
Wow, something is not right there mate and that is VERY dangerous that sort of boost on standard turbos/pistons!
I have a splash boost of 20 secs on my car which is set at 1.4 bar.
When I took my car to get it dyno'd last week Tim at TJ was not willing to run the car at 1.4 bar for he said it was dangerous! And you had 1.75 bar................
Hi Guys, when I first bought my 33, it was set at 1.12 bar with stock turbos. I later changed it to 1.02 bar running it everyday with about 375 rwhp (Dyno Jet). Absolutely no problem with that. After changing to 2540s, I noticed the stock turbos were still okay with no apparent damage at all. I wouldn't hazard a guess as to whether 1.1 would be okay though.