Point of polishing turbo after porting?

[j_eclipse96]

Hi, I searched for this, but I don't think anyone has asked before. Is there any real point to polishing a turbo after a port job? I know you are supposed to sand it smooth, but is it necessary to go past, say, 220 grit sandpaper? Please fill me in. Thanks.

 

[TrboANTsi]

im pretty sure the object of polishing after a port job is to smooth out the passages. especially if it was done as a project by yourself when i helped port out my friends exhaust housing it was pretty rough.

 

[hopwoodp]

"polishing" your cast iron ports is to smooth things out but, also help you see any flaws in the port job . Thats why I start sanding the 80 grit first. It helps me smooth out the ports and see if the path is not that equal or smooth. An 80 grit flapper wheel will help you to correct this and will also tell you if you need to go back to your stone bits to correct the area and then return to 80 grit. I like to finish up the port work with 200 grit. It puts that finishing touch on it and helps you really see how you did your port job.

I don't see any point in going any higher. 200 grit on cast iron pretty much makes the metal look like glass.