sdubfid

I did a brief search but couldn't find anything. Is it possible to make a carbon fiber compressor wheel or would it have been done already?

TheShodan

iTrader: (14)

It would have been done already. The material is strong but doesn't have the tensile strength to be able to handle the heat and rotational speeds that are required from the duties of a compressor wheels. Eventually, there may be a way, but there are no real advantages to it.

Turbo-LS

iTrader: (4)

Billet is the new fangle thing in compressor wheels. and will probably be the industry standard in the coming years i would imagine

ScorpionT

On top of that, a normal process wouldnt allow for such a complex part.


If someone wanted a wheel lighter than billet aluminum, titanium would be the next step. There are currently titanium wheels in production, but the cost is crazy.

TheShodan

iTrader: (14)

^^Such as the Garrett FIA WRC TR30R and the Titanium Alloy wheels used in the Evolution MRs.

sdubfid

Titanium is heavier than aluminum though unless the strength allows less material to be used.

I know some of the larger holset vgts have billet titanium comp wheels used on industrial applications.

jdm95

Titanium is way stronger than aluminum and yes you could use less due to the higher tensile strength, however titanium has a tendency to shear and break apart at high heat aplications and is also more prone to corrosion in high heat situations. This is why in jet motors aluminum alloy is used to make the fan/compressor and turbine blades. Not to mention its not exactly cost friendly and not a huge impact on performance.

ScorpionT

Exactly. BW also has a pretty nice titanium compressor.

In a low stress application like a compressor wheel, a titanium compressor could be made very thin in some spots to save weight. Wouldnt be much though. Like Shodan mentioned, the titanium alloy turbine wheels are available. Those definitely save weight over the Inconel wheels.

No so much shearing from high heat, but titanium does have a tendancy to gall in certain applications, and becomes weak over about 800F. Jets use a huge amount of titanium alloys in turbine engine parts, its actually the largest single use in the world for titanium.

Mikey3000

what do you mean gall in certain applications? 2 parts have to make contact for galling to occur.

what temps does a compressor wheel in our applications see? i seriously doubt 800F, we're talking compressor wheel not turbine.

jdm95

Yes some sections do infact use titanium alloy example fan section due to low heat area vs. turbine or compressor section. also the titanium alloy has low ammount of titanium just enough to give it a stronger traits. In performance jet engines they excede the temp you are talking about and puts it the metal to a weak point more so than a aluminum alloy.
On a turbo charger using titanium just isnt cost effective for the extra performance you would get out of it. The weight savings wouldnt show a large increase in rotational speeds vs. flow applied. I know there are some using it but seems more like a bragging point more than anything at the RPM's the compressor turns at it doesnt matter that titanium is stronger it will still bend or shear the blades and destroy your turbo regardless and as mentioned before it doesnt give enough extra performance to make it worth spending the money for it.
I happen to work on jet engines all day and the same principles go for jet engines and turbos alike the same things hold true whether its a compressor for a jet or a turbo. Im not saying they
are the same but have the same main principles behind them.

jdm95

titanium doesnt have to be at or exceed 800F, under constant heat loads titanium becomes brittle and shears. Also if your using titanium only on just the compressor wheel and not the turbine which does see higher heat loads then what was the point of using it for the compressor since you still have the rotational weight of the turbine. If in fact you have a titanium compressor you might as well be using the same for the turbine also in order to acheive the the desired goal which i would assume would be having it lighter and being able to spool up quicker. This is my train of thought if you disagree chime in.

ScorpionT

I said titanium galls in certain applications, not as a compressor wheel, but titanium on titanium rubbing. Sort of a correction to titanium shearing(has very high fatigue resistance). The compressors dont see high heat, I was just stating that titanium loses strength above 800F.


Titanium is actually heavily used in the compressor and turbine sections, along with tungsten and nickel. Ceramics help with the heat too.

But remember, its not straight titanium used most times. Titanium alloys are used to provide high heat strength. One example, Mitsubishi uses a titanium alloy turbine wheel in a special edition Evo, and it definitely spools quicker than the standard turbo. Similar alloy wheels are also used in racing.

Borg Warner has forged titanium compressors, and they are used because the fatigue resistance needed is VERY high, and they work much better than aluminum. BW has a ton of money invested into their R&D, and if titanium wasnt the best choice, they wouldnt use it. Its definitely not for bragging rights, considering its an industrial/commercial application.