what exactly is a bridgeport?

 

http://www.mazdatrix.com/faq/porting.htm

its quite a bit larger than a street port the term bridge comes from that fact that it leaves a small strip of metal between the ported areas that act like a bridge for the corner seal to ride on.

it also gives you that cool brapbrapbrap idle

 

http://auto.howstuffworks.com/rotary-engine.htm

http://www.ignitionmagazine.co.nz/cars/38

http://www.mazdatrix.com/faq/portbp.htm

this links will help you somewhat...