The covid vacation opened up a little bit of free play and it was perfect timing too! It gave me the opportunity to map my professionally ported npi heads intake and exhaust port so that i can copy each port with a cnc machine.
I used the cnc as a high tech computer measuring machine to map one of the ports by first setting the head up with the port perpendicular to the table. Most inline with the spindle, keeping the port situated in a way to be machinable all around the port surface.
Then i took the tool of choice to be used, a 6" long 1/2" ball rotary file, and started touching off in multiple locations and recording the points on a cad/cam software. Moving down the port every .100" and then circling around the port in multiple points took FOREVER!!! Hours!! But i was determined!! And i will say the npi port is nothing like what the entry port shape is at the begining!
Not knowing what the actual rewards could be from all this work didnt bother me cause i know the entry to these ports are pinched down quite a bit and then opens up considerably. I remember when i purchased the heads, the guy claimed 210cfm intake flow. Knowing how this little bit of info can be debatable with all the technicality of a flow bench, i do know from the years of watching other npi successors, opening the port begining to the rest of it yields great results...so we're going with that!