This might seem like a stupid question, but what's the difference between street porting and bridge porting?is it just size or is it location too. Also about the exhaust porting is the race porting street legal?

 

actually another question too. if i decide to do a 6 port instead of 4 port. what after market parts would i need to replace some of my stock parts and what is also recommended to change. (This is for a 12a engine)

 

Street porting is basically enlarging the stock port of the motor. The next step up would obviously be a bigger street port. However, once the street port opening reaches a certain size the apex seal will actually fall out while traveling over the port. To get around this problem, bridge porting makes two separate ports with an eyebrow shape of material left between. This eyebrow shape that is left between is what keeps the apex seals from falling out when it travels across the bridge port. Hope this makes sense. Some of the other guys can probably explain better or even provide pictures.

 

Your pretty close, the bridge actually prevents the corner seals from falling out, but otherwise right on

 

alright makes sense .... so how much more bigger is the big bridge porting as oppose to the just the regular bridge porting. and which one out of all three do you recommend and what do you recommend upgrading with it. also still need the answer for the 4/6 port bridging

 

Does making street port prevent you from going to a bridge port in the future? Is there a point that once you go down a certain path you can't go back?

 

A street port is "less than" a bridge port so you can always go bridge later. My opinion is to do a "somewhat large" streetport and then you will have good reliabaility (yes, I know bridgeys are reliable too) and I am sure you will be happy with the power gained. Obviously, you will need to have a header and full exhaust along with upgraded carb. I think that the modified nikki can handle a larger streetport, but with bridge you will need a larger carb. I hope that helps somewhat.

 

it helped me lots thanks

 

Also go to mazda trix and I think they have pics of the differences between ports. As for the 4 port and 6 port. A 6 port engine is different from a 4 port engine. Some of the 6 port engines are 13Bs and all the 12A is a 4 port. So, since you have a 12A, it is a 4 port. I hope that makes sense.

 

See Blake's (a 2nd gen club member) site here:

http://www.rotaryengineillustrated.c...-ports101.html

 

cool site .... now i can see thigns visually . thanks for the link its awesome. even though its not for a 12a engine but i see how things are.

 

I thought that I would post here, but I was wondering if I could port a 13B 6 port I haven't been able to find any templates for it. Also what company would you find to port a 6 port?

 

Depends on what kind of streetport it is. If the leading edge of the port is opened up for earlier port timing there won't be enough material left to do a bridgeport later on.

 

Yes you can port a 6 port but alot of companys will not do it because they cant be ported as far as a 4 port can. Call some rotary shops in your area and ask around. Mazdatrix and racingbeat are the two main ones that I know that will not do it whatsoever