I know one if for oil feed, and one is for oil return. What are the other two for?

 

1. water line
2. oil in
3. oil out
4. water line.

 

"Oil in" should be positioned at the top of the turbo... "Oil out" is gravity fed back to the pan.

 

So I can hook up water lines to help cool it also? Does this work well or does the oil work good enough?

 

Oil CAN do the trick on it's own, but you have to allow for longer cool down times than with both. Also depends on how much hot air you shove through the turbo as well. The higher the psi, the hotter the air usually becomes. Nuthin for nuthin though, if ya got it, use it. Never hurts to have additional cooling.

 

running the water helps the turbo run a little cooler and last a little longer, but i wouldnt hesitate to just not use the water lines, its just another thing to break/fail in a high heat area around the turbo. Also most high performance turbos dont use water cooling either. Its a personal choice, you can do it either way

 

Well I'm running 10.5:1 c/r, so boost will only be about 5-8psi.