[erenaud]

Ok, I'll wade in. Almost everything that was in the setup for a supercharger is completely wrong for turbo engine. A properly setup wastegate turbo will have a nearly flat torque curve, from way down low until it runs out of volume capacity somewhere up top. So you don't need to run the engine fast to make torque, it makes the same everywhere. So while higher gears might give you more tire-torque, they shorten the length of the single gear torque sequence, and you can loose boost and power on the shift. So the upshot is that you want to keep a low stall converter, and the gearing should be such that you can get as much of the 0-60 time on 1st gear as possible. Other than that, decide what you want: top speed, fast 1/4 mile, or quickest 0-60 times. All are different setups. The top speed calls for high airflow, which means a big turbo, but it will suffer poor efficiency at low flows, and may even stall, so a higher TC stall may be needed. For 0-60 you want a smaller turbo, so that you get good full boost with minimum back pressure right off the line, but a small turbo is going to run out of capacity long before the cam does. So decide what you want, put some torque curves together, and play with a desktop simulator to see the effects of size, gear, and TC stall. There is no "right" answer, you will need to design the system for what you want.

For starters, compare to the GN: Single turbo 3.8L, set up for 15psi boost, 2060 stall converter, 2.74:1 1st gear (200R4) and 3.42 rear end, mid 4s 0-60, mid 13's in the 1/4. To get similar results out of an SS (4400 lbs vs. 3600 lbs) you would only need about 12 psi, and a 3.08 rear end, with the 3.059:1 4L60E 1st gear with a similar 2060 converter (like the S-10 converter). If you put in low compression pistons (~9:1 or maybe a little more with the cool heads in the LT1) you can easily go to 15 psi, maybe more on good gas (as long as you intercool). With the larger displacement (5.7L vs. 3.8), you need 1.5 times the flow with similar shift points, so that would be like a TA44 or TA49. That setup would give you an almost 20% higher torque/weight ratio than the GN. I guarantee it would get your attention, yet off the throttle it would be docile as a baby.

Stick with the stock cam and rockers: you really don't want too much overlap with a forced induction system. The stock grind is actually not bad for a turbo. Replace the springs if they are over 100k miles.

Lastly, forget about peak HP. What you are looking for is the maximum area under the torque curve, stall to shift point. Worry about your airflow, then make sure your fuel system is up to the task (may need to upgrade both the injectors and the pump). You WILL need a custom tune, consider a wide-band O2 to aid set-up. And don't forget that your going to be doubling the torque you are putting through the 4l60. Make sure it is up to the task.

Oh, and skip the "blow-off" valve. They aren't really needed, and just makes you sound like a 19y/o rice boy.