Gen 3 Hemi dual plane.

A 5.7L hemi has a median port length of 4.380" +-.050". All of the other heads are close to this number as well. All that really happens is the ports size and shape changes but the centerline stays very close. This is the length of the port from the entrance to the back of the intake valve seat in the head. It will vary slightly and is dependent on a few variables but won't change too much. My intake runners have a median length between 7" and 7.5" long. Due to layout and package they are as close as they can be. So the total runner length is between 11.38" and 11.88". Again dependent on some variables that can't be controlled. If you run a comp 268H-13, installed at 113 deg and apply the sonic ram theory with the cam timing and port length, it comes out to 11.513" to be on time for the 4th pulse. Now there is more that goes along with this to make it work like cross sectional aria and ETC, ETC. but I like to think that I am on the right track until proven wrong.