Turbocharger impeller wheels

[Steinoff]

I want to redesign the turbo impeller wheels in my turbocharger to help the spooling issue that the large turbo has.
I was wondering what material the impeller wheels are made from.

Thanks in advance,Stein

 

[Metalguy]

The compressor side is usually an Al alloy, and the turbine side is a superalloy of some kind.

If you think you're going to be able to improve the design you must be a real good engineer!

 

[TVP]

Other materials that have been used for the turbine side include the intermetallic TiAl and ceramics like Si₃N₄.

 

[Steinoff]

Metalguy, I want to redesign the wheel slightly to attempt to eliminate some of the excess clearances in the turbo. If the thing touches down anywhere im dead and I realize that . Also I think I may find that the blade design I want to run with may help spooling but may also cause a ton of backpressure .
I just want to exhaust my ideas and I will share my findings and go down with the ship if its a failure. It will be fun if nothing else.

Thanks for the reply's so far, Stein

 

[Tmoose]

Not sure if the clearances are really "excess".
The ball bearing turbo folks >>claim<< their turbos spool up quicker than those using sleeve bearings.
I have a feeling an exhaust housing with a small A/R (requires a wastegate) and a shot of air injection (ala Porsche in the early 70s) or even NOS just to get the Turbo cranking would yield bigger results.

If your app uses carburetors than manifold length is important too.

 

[Steinoff]

The addition of a CO2 blast helps spooling and nitrous is the fix for sure to get a lazy motor onto boost quickly. But it is frowned on in drag racing, especially nitrous in a class that is limited to one power adder.
Kepp the suggestions coming they are all great.
Thanks,Stein

 

[Metalguy]

Steinoff,
Here's what to do, and I want a big cut of the profits when you go commercial. Design a variable A/R housing! Much easier/better to improve something stationary than spinning.

 

[Steinoff]

Metalguy, You have me thinking and its also a great idea but the impeller is so crude that I must attack it first.

Thanks again ,Stein

 

[Majik]

You running a t3 or a t4? The t3's came with a split port or a single open port. The split port helped reduce lag. Also If you are going to let the turbo cool after each round then i know some people who have put CO2 directly into the turbine housing... The positive of this is the turbo will instantly spool. The negative is that the exhaust turbine will be ice cold after the 'shot' and then will be heated up be the engine exhaust... they've been known to crack that wheel but work very well... Also to get around that 1 poweradder rule some people have say an incar fire extinguisher system.. if you put two of them in and one's filled with CO2 and the other's filled with fire extinguisher stuff then it's only a matter of plumbin You could also get into "twin scroll" and VATN turbos but I don't think that's gonna help much on your lag issue. I highly doubt you will design your own wheel but if you are persistant research the Nasa jet propulsion labrotories PDFs for all sorts of information on turbine blade design and technology.