Turbo Compressor Wheel Profiles

[Rowdyr32]

I was looking at my turbo this afternoon and it looks like the compressor wheel has been cut or the wrong housing is fitted. So I pulled it off for a closer look. I know at work we shim our gas turbine impeller clearances to 0.010". Dad was saying that in some pumps they use the same housings and modify the impellers to suit thier flow rates/pressures. Is this the case here or has the turbo builder been lazy/dodgy?

There is about a 3mm gap between the housing and the front of the blades at the rear of the impeller. I can't see how this would make the turbo spool faster since it is making the compressor less efficient.

In the pics there is a stock turbo next to it on the right to compare.

[Roy]

Its not so obvious in the pics...but what you describe is a bit unusual.

Normally with compressor side of things, the housing is machined to accomodate the compressor wheel. I have never heard or read about the trimming of a compressor wheel to clear a housing.

On the flip side, often the turbine is trimmed/back cut to improve flow and reduce back pressure. And again the exhaust housing can be machined to clear a bigger turbine...but gettign back to the compressor side...i cant see why you would want to cut back a compressor.

There are sometimes little nics in the compressor which are a result of balancing...could it be the compressor has hi flowed itself with shaft play

[Rowdyr32]

It doesn't look like the wheel or the housing have been machined. If you look at the first pic at about 3 o'clock you canb see how far back the impeller is sitting from the housing. A bit NQR. There is also nearly no shaft play and they haven't contacted. The car already goes hard so hopefully I can make it faster.