GT Wheel in T04b

[Chezedik]

I have heard they are using the T04b housing on some of the GT turbos, and so you can use the GT wheels from them. Does anyone know? It would be a great way to boost efficiency.

[C-Kwik]

Are you talking about using a T04B turbine with a GT compressor? Or just the turbine housing with an unmatched turbine wheel?

[Chezedik]

I think I was told at one point some of the GT wheels were matched to the T04B housing, do you know if that is true?

[WDRacing]

What exactly is the differenc between a "GT" wheel and a "normal" wheel? Honestly, I didn't even know there was a difference and like I've said before...I'm a pretty Fart Smucker!!

[Chezedik]

The GT wheels have been redesigned for what they claim is 'better aerodynamics'. This equates to higher efficiency numbers. People tend to think this is because of ball bearing. But all ball-bearing does is allow for faster spool. This means you can run a bigger turbine than you would have otherwise. So if I use a GT wheel with my T turbo, I should get efficiency levels that are roughly like those in the GT turbos, but with slower spool.

[WDRacing]

Is the price of the wheel worth the efficiency gained by the swap? I have to rebuild my TO4R..well, its an R compressor and wheel with a BB center with a HUGE .81 AR T4 exhaust housing. Might as well use a GT impellar wheel if I get the chance. This is going on my LS1 by the way, not the KA. The KA has outlived it's usefullness Time for bigger is better Here's another random pic for you

[C-Kwik]

For best results, you should use a wheel that is matched to the wheel (compressor and turbine side). Using a larger or perhaps even a different trim housing is going to leave more space between the wheel and the housing. Not sure exactly what happens on the compressor side, but I'd speculate decreased efficiency and flow (for a given compressor wheel speed).

On the turbine side, it will increase flow, but at a cost of turbine efficiency. Turbo manufacturers go through a lot of R&D and testing to optimize flow and efficiency. If there were any acutal gains by doing something like this to your turbo, the turbo manufacturer would probably already be doing it.

[Chezedik]

That seems reasonable to believe. WD if you are interested, I got the info from a guy at turbochargers.com.

[Chezedik]

An email reply from Turbochargers.com:

from a Garrett GT line yes you could get a GT30 comrpessor wheel and it would make considerable gains!you would have to repair it along with replace the wheel!how much HP are you looking for?thanks

Of course, I have already rebuilt mine, but it would be just a wheel change that yeilds a 78% efficiency. Yes, I know that is a T04e, but it is also just a wheel change. I don't know, it is what it is.

[lrb_2000]

Is the price of the wheel worth the efficiency gained by the swap? I have to rebuild my TO4R..well, its an R compressor and wheel with a BB center with a HUGE .81 AR T4 exhaust housing. Might as well use a GT impellar wheel if I get the chance. This is going on my LS1 by the way, not the KA. The KA has outlived it's usefullness Time for bigger is better Here's another random pic for you

You can rebuild Ball Bearing turbos?

[Chezedik]

Not yet. Garrett is still only offering the CHRA with backing plates and wheels. In fact, the only part they are selling separate is the compressor wheels.

[C-Kwik]

An email reply from Turbochargers.com:

from a Garrett GT line yes you could get a GT30 comrpessor wheel and it would make considerable gains!you would have to repair it along with replace the wheel!how much HP are you looking for?thanks

Of course, I have already rebuilt mine, but it would be just a wheel change that yeilds a 78% efficiency. Yes, I know that is a T04e, but it is also just a wheel change. I don't know, it is what it is.

Unless the overall dimensions of the GT 30 are the same as the T04 compressor it's replacing, then this would be really porr advice. It's hard to say what the actual discussion is as it looks like involves emails going back and forth. Sounds like you might be getting some really poor advice.

A compressor wheel that is not matched to a compressor housing correctly will not yield the same efficiency. The wheel is only a part of the turbo and works with the housing to compress the air. This is absolutely critical to efficiency.

http://www.nissanperformancemag.com/april06/nerds/

This article isn't specific on this subject, but gives some insight into how boost occurs in a compressor. I normally wouldn't link to a competing site, but Mike Kojima is an exceptionally knowledgable turbo guru and it might be better to hear it out of the horse's mouth so to speak.

[Chezedik]

Actually, the other side of that was me entering the question on a 'contact us' form. I just had mine balanced and coated, so I am not likely to do it, but I was wondering.