Hey, does anyone have a blueprint/measurements/math behind port shapes? Including stock port, streetport, bridge, etc. I’ve looked online and haven’t really found much. Thanks

 

its sort of less math and more "make it as big as you can before stuff falls in there"

so the curved inner part can only go so far before it gets into the oil seal track. the outer side can only go so far before the corner seal falls in, which is why a bridge port is done, it supports the corner seal

the bottom is the port opening, which you can do something about. and then the top part is port closing, which also has a lot of flexibility.

the math part would be to figure out the port area (Mazda published the FD and Rx8 data).

 

Its magic to me!

 

any way someone has the measurements for a porting template? I have a cnc and a laser cutter and would like to experiment LOL

 

This page has an interactive graphic showing port timing and shape

I have attached a 1:1 scanned Turbo II secondary port in PDF format to get you started. An outline for the dowel is on the sheet as well.

Keep in mind it's not just the aperture, but the shape of the runner ("the bowl") in the iron that also affects performance.
This video shows that well with flow tests:

 

My reply didn't show up at first, but this additional post makes it appear.