Best position for radiator?
 

I have an FD that is getting the LS1 treatment and will have a custom radiator made. What is the best way to position the radiator? Should it be tilted forward, stand strait up or something else? Is one position more effective? I'll be using the 99 spec front bumper, aid guide, and undertray. No intercooler or other parts in the way, if that makes a difference. If someone could point me in the right direction to get nswers, that would be just great.

Generally perpendicular to the air flow is best, but that's going to limit your volume in an FD.
I think most people tilt it forward so the radiator can be made taller. Put in some ducting to the air doesn't get around it, add a good fan and your ready to go, AFAIK.
Good luck.

If the radiator is ducted properly there is no reason not to tilt it and save yourself some room. If you have plenty of room anyway do whatever is convenient.

Thanks guys. I'll probably tilt it forward and put a bigger one in with ducting and all.

So, the air just runs past the engine and back under the car behind the sub-frame? Would a vented hood like the Scoot model be more efficient at getting the air to flow better out of the engine compartment or does it not really matter?

A ducted vented hood is better; you have to have a duct to direct the air leaving the radiator and make it go up over the car. Just like the duct for air entering the radiator, you do not want to have any gaps or openings that gives the air anywhere else to go except where you want it to go. Air leaving the radiator and being ducted out an opening in the right place out the hood can make quite a bit of downforce :) Several LeMans BMWs and Corvettes do this to make more front downforce. I would do it on my racecar, but it is not legal in my class.