I'm leaning more and more towards rebuilding the four cylinder engine, the twisted logic behind this is the money I would have to spend on a bigger turbo and time and materials to mount it on the 3400 should be nearly equal to the four connecting rods and four pistons I would need to make the four cyl work. The factory exhaust manifold for the 3400 might work, they are cast iron, but the crossover is regular pipe and has a flex piece in it and I don't think that would be good for the turbo, maybe I'm wrong, don't really want to be wrong and have something melt down or break. So I'm planning on using Eagle 6.25 inch long, small journal Chevy rods part number CRS6250SLW, they are H-beam con rods and they are rated up to 600hp in a v-8 so 300hp in a four cyl, and I'll be under 200hp, so should be good. Pistons I plan on using are Icon IC723 designed for a ford, but the numbers work for my application. Using the flash driven calculator on the Eagle home page, the rod and piston combo will give me a 8.4:1 compression ratio, assuming a .04" head gasket thickness, and 45.6cc head volume. I plan on working the combustion chambers and opening them up, if I can open them up to 47cc that will knock me down to 8.3:1 and if the head gasket is .05 that will drop me down to 8.12:1 and that is a good turbo compression. Since I don't plan on running over 7psi.
If anyone is interested, the specs I used are:
deck height 9.125
bore 4.03
stroke 3.00
rod length 6.25
chamber vol 45.6 47
gasket thick .04 .05
piston dome -28.5 ( don't for get the minus sign!)
pin height 1.365
