The second-generation (Gen II) LT1 small-block Chevy engine (SBC) was originally introduced in the 1992 Corvette and used in other GM models until 1997. No longer being produced, its 350-cubic-inch displacement was achieved with a 3.48-inch crankshaft stroke and 4.00-inch bore. The 383ci LT1 -- an aftermarket displacement never produced by GM -- is achieved by replacing the original crankshaft, rods and pistons with an aftermarket rotating assembly that has a 3.75-inch stroke and 4.030-inch-diameter pistons. Camshaft selection for this combination depends on a number of variables.
The factory hydraulic roller camshafts specs varied depending on application. LT1s used in full-size passenger cars had milder cams that produced power in a lower operating range than the engines in the Corvettes and other smaller sports cars (Camaros/Firebirds). The application of your 383 LT engine (no longer an "LT1," technically) will help determine the camshaft selection. The increase in stroke -- and displacement -- alone will tend to move the operating range down a few hundred rpm. This gives some room for a slightly more aggressive camshaft lobe profile.
A good example would be the Comp Cams Extreme Energy 266HR camshaft. A camshaft with this lobe design will have operating range of 1000 to 5000 RPM, offer increased economy, torque, a mild performance gain and will work well with the factory computer.
For increased power output, the Comp Cams Extreme Energy 276HR camshaft moves the rpm range up to 1,500 to 5,500 and is designed to be used with custom computer tuning. It works well in a daily-driven car but has a slightly choppy idle. Because of its increased duration, higher rpm range and increased valve lift, upgraded valve springs are recommended.
The Comp Cams Extreme Energy 292XFI HR camshaft could be a good selection for a high-performance camshaft, but other modifications to the car such as a lower gear ratio and higher rpm stall speed torque converter are required. The rpm range for this cam is between 2,200 and 6,200, and idle quality is rough. Upgraded valve springs as well as rocker arms are required for this camshaft, and the computer will need to be re-programmed, as well.
