small block headers

FWIW, here are some rules of thumbs regarding header design;

1. The diameter of the tube determines the rpm at which the torque peak occurs. Larger diameters give higher rpm torque peaks and visa versa.

2. Tubing lenght rocks the torque curve around the torque peak. Longer tubes increase the torque below the peak and visa versa.

3. Larger diameter collectors favor the torque above the peak and visa versa.

4. Longer collectors favor the torque below the peak and visa versa.