im having trouble deciding which port to go with when i rebuild a 12a for my rex.
my two choices are
mild port
extend port

the biggest problem is everyone seems to call the porting something different,
and some companys have 3 different types of street porting alone?

as most of you know i already have alot of goddies on my engine,including a custom-rb exhaust,

i plan to add a new carb on the engine when its done,

i want to keep it drivable,but it doesnt get drivin everyday.

if im correct the "mild port" is one step up from "stock or standard port"
and the "extend port" is two steps up from "stock or standard port"

i dont wish to go any higher then that
i still want descent drivability with noticable horsepower gains.

 

bump

 

go a huge extend port it will give you alot more power while retaining drivabiltiy, you should also get a h/d clutch and lightend flywheel

 

already have the hd clutch,
but no lightweight flywheel.

is a huge extend port the same as a big street port?
or are we talkin j and bridgeport now?

 

ok lets see. as per Felix's Own General Rotary Car FAQ. well just take a look, http://mrmazda.members.atlantic.net/....html#APORTING
or go here for pics, http://www.mazdaracing.com/engines.htm

 

i checked out the links,didnt care to much for the site with the pictures,there so unrealistic.

"Peripheral Port (picture coming soon) - This is the #1 port for any All Motor rotary race car. The intake ports on a peripheral port engine are similar to the exhaust ports and are located in the rotor housings above the exhaust ports, the factory ports are filled in with Devcon. Stock apex seals are NOT ok with this motor"

come on,why dont they mention the motor will bairly hold idle below 2,000 rpm and it will only last a couple months to a "maybe" year?

i feel sorry for someone who doesnt know **** about porting and goes through them,the'll end up with a j bridge on a daily driver.

i may not know much about porting but i do know a peripheral port is insane.

 

i was also concidering doing some of my own porting,
on some test pieces of course.
but i wanted a video to show me the ropes,
does anyone know where i can get a video like this?

i was thinking of buying some spare housing and sending one in to get profesionally done,
then trying to duplicate it on another.
i have some of the tools and the porting templates.
but if i had a video to learn the tricks of the trade im sure the whole process will be easier.

 

bump.

 

extend port and street port are often interchanged with each other... and extend port "extends" the port upwards so that it closes later. so does a street port. there isn't much done with one of these as you cannot move the long side of the port opening or the oil control seals will pass over it and you'll burn oil like crazy, and the opening (vertical) side can't be moved much because the corner seal and apex seal need that space (which is where bridge porting comes in - the bridge of metal is left to support the seals). so all you can really do without going bridge or peripheral is extend the port closing time so it closes later. it's a very streetable port (and can make more torque across the entire rev range) so it's often called a street port.

 

so there is no diference between a wild street port or a mild street port?
except a wild street port might actually be a bridge port.

what about the videos?

 

well, the extent of the street port will vary... some street ports are indistinguishable from stockports, others are truly enormous and are as large as you can physically make them without dropping seals or going fishing in the cooling system...

 

according to Felix's web site the Australian 12A has different port timing from the USA spec. He gives 16.5 overlap, exhaust 75 BB/48.5AT intake 32 At 50 AB

Are there any reasons for the extra 10.5 degrees of overlap, did it produce additional power, weas it also used in any other market?

 

Come on, like you spend much time below 2000rpm except when idling? I drove my '85 12a bridgeport around with no trouble around town. I wouldn't purposely sit in traffic though with it. OFcourse a perpheral port engine is not as long lasting a bridgeport. Perpherals is good for weekends on backroads and road tracks, at the end of the year, you replace your carbon apex seals and get back on the road. If you spend much of your time in traffic, you have a rotary for all the wrong reasons. Drive your geo or useless sport utility to work. If you are stuck in traffic most of the time, you live in the wrong place.

Anyway the bridgeport didn't drive any more difficult then a street port 12a I drove too. Infact it made more power..he he... And the fact it idles at about 2K means your that more close to the powerband. Why does it matter were it idles as long as it does?!