Are Ceramic Turbine Wheels Really That Bad?

[VB-]

got to thinking about this recently, and even did a little research basically it started with searchin for why manafactures use them, it would seem that they help the turbo to spool up quicker, so im assuming ceramic as a matrial is lighter than steel, and im sure you'd all agree, quick spooling is good! hey, they might actually been onto sumthin here with ceramic....

after a while of searching, i kept getting drawn back to the fact that they seem to have this habbit of falling apart, not good, but this seemed strange to me, as i've heard (and i'm sure some of you have too) the stories of manafactures experimenting with ceramic engines, like piston and blocks, but they just didnt wear out, so there was no scope for spare parts sales.... hrmm.... (has anyone on here got evidence/heard the rumors of such testing, or who did it?) so if ceramic is this good, how could the turbos fall apart i thought, well, after stumbling across sum info, it would seem that it is the epoxy that lets go with the heat (my understanding is epoxy is used to hold the turbine wheel on cause cermaic cant be welded to metal)

the only thing i've heard against these turbos is the turbine wheels falling off, nothing else really. but they spool up quicker, and theres no reliability issues with ceramic (especially not from heat). if someone was to develope sumthing to hold the wheels on, whether it be an epoxy, or a locking mechanism even, then there could be some serious potential there. turbos could run huge boost cause they wouldnt fall apart from heat stress, and theres less inertia loading (if thats what its called) on lighter wheels, not to mention, would be easier/cheaper to manafacture than titanium, and titanium is where its heading next for the biggest 'n' best.

what am i not thinking about here? what have i left out that will confirm that ceramic turbos are just sh*t,please fill me in. let the flaming begin!

cheers,

Ben

[paulr33]

for standard boost pressure and standard engine setup (ie: user not cranking up boost, changing stuff etc) the ceramic wheel is fine and offers advantages over steel. ie: weight being the main one. i assume cost would be important also.

steel wheel is only required when more exhaust heat is coming out, ie increase boost pressure and an engine work lots harder than factory OEM specs.

cermaic wheel = perfect for standard application that it was designed for

steel wheel = suitable for increase power and engine power

[danielson]

for standard boost pressure and standard engine setup (ie: user not cranking up boost, changing stuff etc) the ceramic wheel is fine and offers advantages over steel. ie: weight being the main one. i assume cost would be important also.

steel wheel is only required when more exhaust heat is coming out, ie increase boost pressure and an engine work lots harder than factory OEM specs.

cermaic wheel = perfect for standard application that it was designed for

steel wheel = suitable for increase power and engine power

this doesnt really answer this guys qtn....

theoretically what your saying is true, but the other problem with the ceramic is the fact that it cant hold together with very high centrifugal force, eg high turbo rpms.. Im sure though some company is working on doing a lightened setup, is only a matter of time i think..

[2rismo]

Standard turbos are great for 11's

[shif_tea]

Standard turbos are great for 11's

lol with a 150hp shot of NOS maybe

[sh@un]

Standard turbos are great for 11's

Standard turbos are great as paperweights.

Back to the guys original question- A manufacturer would be crazy NOT to coat as much as possible with ceramic if it indeed 'never wore out', just think, they could claim to have the most durable, longest lasting engines of any manufacturer! But, in the world in which we live, if something rubs across something else (especially with additional heat being supplied), things are just going to wear down eventually, lubrication or not (geez, sounds kinda sexual, dun it *LOL*)

[Munna1]

got to thinking about this recently, and even did a little research basically it started with searchin for why manafactures use them, it would seem that they help the turbo to spool up quicker, so im assuming ceramic as a matrial is lighter than steel, and im sure you'd all agree, quick spooling is good! hey, they might actually been onto sumthin here with ceramic....

after a while of searching, i kept getting drawn back to the fact that they seem to have this habbit of falling apart, not good, but this seemed strange to me, as i've heard (and i'm sure some of you have too) the stories of manafactures experimenting with ceramic engines, like piston and blocks, but they just didnt wear out, so there was no scope for spare parts sales.... hrmm.... (has anyone on here got evidence/heard the rumors of such testing, or who did it?) so if ceramic is this good, how could the turbos fall apart i thought, well, after stumbling across sum info, it would seem that it is the epoxy that lets go with the heat (my understanding is epoxy is used to hold the turbine wheel on cause cermaic cant be welded to metal)

the only thing i've heard against these turbos is the turbine wheels falling off, nothing else really. but they spool up quicker, and theres no reliability issues with ceramic (especially not from heat). if someone was to develope sumthing to hold the wheels on, whether it be an epoxy, or a locking mechanism even, then there could be some serious potential there. turbos could run huge boost cause they wouldnt fall apart from heat stress, and theres less inertia loading (if thats what its called) on lighter wheels, not to mention, would be easier/cheaper to manafacture than titanium, and titanium is where its heading next for the biggest 'n' best.

what am i not thinking about here? what have i left out that will confirm that ceramic turbos are just sh*t,please fill me in. let the flaming begin!

cheers,

Ben

Interesting post Ben a locking mechenism sounds like a good idea will be interesting to hear peoples opinions on this.

cheers

[paulr33]

i dont think its common for the wheel to actually come off the shaft as its bolted on with a locking not. the blades actaully detatch themselves from the shaft due to excessive heat, that is the ceramic actaully breaks off.

this is whats known as "ceramic in cat disease". shards of ceramic exhaust wheel end up stuck in the cat. usually a turbo that has a busted exhaust has one or two blades fractured off or missing but the rest are in tact and still OK

[RBwhatever]

I've heard as soon as you start boosting the stock turbo, even though it might not break you dramatically decrease the life of it....

[sewid]

Ceramic exhaust wheel turbos are great. Now please buy mine.

[Beer Baron]

paulr33 the most common breakages i've seen are wheels coming off shaft, or rather shaft breaking at the base of the wheel. i've never seen blades just fall of a wheel like you describe. have you actually seen this? you get bits of ceramic everywhere because as it starts to detach from the shaft (or shaft is breaking) it spins out of allingment bashing itself to pieces on the housing. i think what happens is the epoxy stops holding the thing properly to the shaft this causes it to spin out of allignment which can then break the blades off against the hosing, or cause the wheel to break off completely. but i dont think the blades just fall off an otherwise healthy turbo due to extra heat. i could be wrong though, i'm no expert on turbo failure!

[paulr33]

the t28 that i have at one was like how i described, attached fine just two blades died. one completely came off, the other broke in half.

it must go through some intense stress for the shaft to actually fail and come off. ceramic blade failure i can understand but the whole shaft coming off its pretty cool

[GTRgeoff]

A number of issues we investigated with turbines some time ago in aerospace applications of ceramics. With the radial loadings they "grow" which results in greater surface tension, will occur especially when overboosted from stock. A slight impact can cause catastrophic failure which is common enough on GTR turbos after they have been removed for some reason, as it would make sense that a turbo that has run faultless for years will suddenly throw a turbine and the only other factor we can summarise is a loose particle striking the turbine blade, snapping or damaging it and the rest is easy to imagine.

A failed GTR turbine often results in an engine rebuild due to ingestion of the particulates. Some suggest as often as 2/3 need rebuild.

No amount of adhesive will protect it as needed.

So a summary. If not removing and keeping stock boost then leave the time bomb on to tick slowly. If upping the boost, expect the worst if you can rationalise the risk vs return and accept it. If the need arises to remove the turbo, expect the risk to increase dramatically but if you survive the first week it would seem you dodged the bullet. Sorry Sewid, just the result of experience and research. One of my GTR34 Vspec turbos let go at 5 psi within the first 2 hours of startup after fitting. Cost to rebuild GTR turbos comes in at about 2800 with steel wheels last I checked. GT-SS equivalents from Garret are less than that. Having wasted $800 on the last set I'm not sure I would do it again since I CBF rebuilding these at that cost.

So lets get to the "right" ceramic compound. Inconel as used in axial flow turbines (jet engines) and R34 N1 turbos. Can handle the conditions, less likely to self destruct and lightweight. Everything the ceramic stockers need to be but at a cost.

Also, you can't just run the boost as high as you want. There is still flow characteristics and excess heat to consider.

[Beer Baron]

the t28 that i have at one was like how i described, attached fine just two blades died. one completely came off, the other broke in half.

it must go through some intense stress for the shaft to actually fail and come off. ceramic blade failure i can understand but the whole shaft coming off its pretty cool

yeah i've seen one and it looked like a rose bud someone had just snipped off at the stem... lol.

i guess it's hard to always determine cause due to the generally destructive end result. it maybe it spun slightly out of balance, contacted the housing, lost part of a fin, which cause more imbalance which then proceeded to bash itself to death on the housing.

it seems the only real viable option is steel wheels.

[PHATR32]

shit, so your saying if you remove a turbo it devreses its life dramatily?

i had one of mine removed, and move so many times its not funny!!

[2rismo]

It's only 100hp not 150

[GTRgeoff]

It would appear that it increases the chance of failure, possibly because of particles getting dislodged that later separate and strike the turbine at a moment of greatest inconvenience.

[VB-]

well, i havent had alot of hands on expreience with these turbos personally (hence i came here) but i thought the common problem was exactly what beer baron said. the epoxy lets go, 100,000rpm of ceramic gets to know the turbine housing a bit better, and you end up with the rosebud sitting infront of the cat.

GTRgeoff makes a good point, i think... i didnt really get alot of it lol, but i still value the input, keep it comin

cheers,

Ben

[ZILR-34]

so im assuming ceramic as a matrial is lighter than steel, and im sure you'd all agree,

cheers,

Ben

u have just Answered ur own question. ceramic is more lighter than steel and more Flexible. when turning up the boost there is more air pressure goin into the turbo which the ceramic as a matrial can only flex so much b4 it comes weak and breaks or bends. i myself never seen a turbo blade brake off unless ur running like 25psi of boost. but wat i have seen is when u turn up the boost to above 14psi the ceramic wheel will come weak and bend forward which will start hitting the front housing (shaft play) and start grinding its self away into ur engine intake system. as for steel under pressure it will resize only 1-2% as for ceramic its more like 4-5% which will cause shaft play and then the damage starts.

hope that Answers ur question

[GTRgeoff]

u have just Answered ur own question. ceramic is more lighter than steel and more Flexible. when turning up the boost there is more air pressure goin into the turbo which the ceramic as a matrial can only flex so much b4 it comes weak and breaks or bends. i myself never seen a turbo blade brake off unless ur running like 25psi of boost. but wat i have seen is when u turn up the boost to above 14psi the ceramic wheel will come weak and bend forward which will start hitting the front housing (shaft play) and start grinding its self away into ur engine intake system. as for steel under pressure it will resize only 1-2% as for ceramic its more like 4-5% which will cause shaft play and then the damage starts.

hope that Answers ur question

Mate, the ceramic is in the turbine, or exhaust wheel, not the compressor. They use ceramic for the weight and heat resistant properties. Ceramics don't bend and have a very finite limit in tension so the speed of the rotation causes them to try to stretch, allowing them to "grow" off the shaft so the adhesive has difficulty holding it in place. The blades can also just snap of under the centrifugal tension. Then there is blade separation/balance failure/shaft failure.

I'm still not quite sure what you are trying to say. Do you know how many GPa of tensile pressure it takes to make steel and ceramides to increase in size? And what those tensile rupture limits are? And if the blades grow, how does that cause shaft play (which is also growing under centrifugal loadings due to its own mass)?