I am just wondering what is the difference between the two. If anyone could help me out I would appreciate it! I'm trying to decide what to do for my 1991 rx7 n/a coupe.

 

Street porting is a mild rework of the ports, bridgeporting is a hog-out port job. There is more power to be made with the bridgeport but the idle has to be kept high if you run it on the street...somebody already has the links to some pics, so I'll let them jump in since this is a common question even in this New Member tech board.

Mario III

 

Your only reasonable option is a street port.

Am street port in the 6 port NA generally just opens the ports a little earlier and closes them a little later. The result is a top end gain (maybe 20%) with some sacrifice down below. You can run the stock intake, stock ECU, and just upgrade the exhaust.

A bridgeport cuts another port between the intake port and the rotor housing:


This is because the intake port has been ported as far as it can go towards the rotor housing, so a small bridge is left for the corner and side seals to run on and the port is then continued on the other side, even into the rotor housing. You will need to ditch the stock intake manifold, run a standalone EMS system and upgrade to a free flowing (loud!) exhaust. Power gains are much more substantial (100+ HP) but low end is severely reduced, exhaust volume is high, and fuel economy goes into the toilet.

 

I will say thank you for this. Explains so much more. Thank you

 

Thanks so much for going over this. Fairly new and didn't know what either were.