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What is the different between those two compressor housing? if the one with hole to prevent compressor surge? is there an advantage of one over the other?

 

the turbo with the little holes has a compressor surge housing and the one without holes doesn't have the surge housing. Call the ppl selling the turbo and they can tell you the difference and what it does. I talked to the owner of that shop before, they are good people.

 

Yea, my friends and I all take our cars to TDAutowerkes for tuning, so I'll go ahead and vouch for them, and outside of that, I would definitely get the "one with the holes". Those holes are there for a reason (that a smarter man than I would know), and almost all of the newest gen turbos have them-the turbonetics GT series for instance. Actually- does anybody know what those do?

 

That turbo doesnt really need the ported cover, usually you would only do that on something bigger like the SC6176.

 

I believe the ported shroud help with surge at high flow rate but it decrease the compressor efficiency

 

http://www.turbobygarrett.com/...103_3

"A Ported Shroud compressor (see Fig. 2) is a feature that is incorporated into the compressor housing. It functions to move the surge line further to the left (see Fig. 3) by allowing some airflow to exit the wheel through the port to keep surge from occurring. This provides additional useable range and allows a larger compressor to be used for higher flow requirements without risking running the compressor into a dangerous surge condition. The presence of the ported shroud usually has a minor negative impact on compressor efficiency."