Don,
I'm just a bit ahead of where you want to go, but way behind on the rest of the plane. I'm wingless in the garage at home, test running in the yard with the tail tied to a cedar tree.
I'm building an RV-8 with a turbo 13b. I welded up my own exhaust manifold mounting a Turbonetics 60-1 using an 'on center' TO-4 turbine housing. The compresor faces forward and a cone shaped K&N filter is direct mounted to the compressor housing. The exhaust is an S shaped 2.25" pipe that crosses in front of the firewall and exits out the center of the cooling air exit (cowl flap area) parrallel to the sheet metal ramp. The pipe is supported with a clevis to the engine mount plate (between the block and oil pan) so it all moves in harmony with the engine/turbo, yet can grow a bit from heat. So far the turbo muffles the engine fairly well.....but I have not gone to War Emergency Power.....yet.
I 'borrowed' David Leonards radiator advice, and mounted it under the chin, making a fairly generous scoop, which I tested today.
the oil cooler is mounted on the right side and uses the entire airflow from the right cowl cheek opening. Separate air paths for radiator and oil cooler helped solve my previous cooling failure.
I ground ran for 20 minutes today, building up RPM as it warmed up, and the temps are stable. I chickened out and held at 3850 RPM for the last 5 minutes, the highest I've gone yet. water temp stable @ 154F, Oil stable at 172F. Tracy's engine monitor gives direct HP readout based on fuel flow, so it varies as you adjust the mixture, but I ran up to about 50HP with firm temperature control. This was very exciting for me becuase it's enough power that the fuselage is starting to buck and shake like there might be some power there, and promises of more.
I have not done anything with the left cowl cheek opening yet. Air entering here goes right to the tubo air filter, and washes over the fuel injectors, turbo assembly, and spills out the bottom with the heated radiator air.
To keep from choking the heated radiator air, I'm thinking of making a duct to carry the left cheek air out the left side of the cowl, where I could mount an intercooler. I've trial fitted a stock Mazda intercooler here, I would need to remake the air tubes into/out of it. The important part of this is cooling the fuel system and isolating the turbo heat from anything it could damage. Dave warned me of this early on, and I have not forgotten it.
Constructive comments are always welcome!
Scott
PS, I'm working very hard to keep this simple and light. Weight adds up fast!