Is there anything that can be done about rusting & blemishes on the exterior of the turbine housing? Older turbos start to look bad but is there any kind of polishing or coating that can be applied to them?

Doogie if you can take your turbo apart the best way to refresh and unrust it is with the use of electricity

here's how to do it
things you need
1 12V DC power supply or battery charger that can produce at least 10 amps continuous
2 a bucket big enought to hold a gallon of water, the part to unrust and more
3 a stainless steel plate that is at least as wide or wider as the part you want to unrust and tall enought so that the top edge is out of the water
4 a box of baking soda

how to do it
MAKE SURE THE DC SOURCE IS TURNED OFF FIRST
Put enought warm water (around 110-120F) in the bucket to submerge the part you want to unrust
Add the part in the water and put the NEGATIVE electrode on it, it is ok if the negative electrode is submerdge
next put the stainless steel plate in the water, make sure there is no physical contact between the part to unrust and the stainless steel plate
Put the positive electrode on the stainless steel plate, make sure the electrode is OUT OF the water it must stay dry all the time
check again if there is no physical contact between the part and the plate
Turn on the DC source
Start to add baking soda in the water, you will see the amperage going up, usually for a gallon of water you will need around 1/4 of a 1 pound box
after 1 hour turn off the dc source and start to turn the part
only the metal facing the stainless plate is unrusted so you will have to turn it often, electricity travel in a line of sight
Do that for a few hours and you could have spectacular result even cooked oil will start to leave the part

one finished let the part dry in a warm oven (around 250F)
As a general warning turn off the dc source everytime you will need to move something in the bucket if not you could get an electric shock

AND RESPECT THE POLARITY ! unless you want to unrust the stainless steel plate and put more rust on the turbo housing :)

Alain

Hey thanks man... that's what I was looking for!

HI, My Best advice to you is, Sandpaper, Wetsand with 120 grit intil nice and smooth. It will bring out fresh metal to polish or coat and make real pretty. I have done it on both mitsus eclipe 1997 and talon 1997 so far Look at the powdercating after sanding

http://upgradecar.blogspot.com/2007/10/powder-coating-is-done.html

But alains' way is more dangerous and scientific, thus cooler.

:7