Eriks85Rx7

I have thought long about going to turbo but im thinking i want to stick to N/A. I believe my 12a could use a rebuild this summer and would like to know how fast a 12a bridge port is( with supporting intake and exhaust mods) ? Would a bridge port 12a be more reliable than a turbo 12a?

According to the sites i have read about rotary porting, a bridge port 12a can be expected to put out almost 300hp?

81gsl12a

iTrader: (1)

woa killa 300 is monter j bridge port......well make good power will have a shot life 6 months if you are lucky bridge port is errr like 240ish i think

DriveFast7

iTrader: (1)

my 12a j bridge dyno'd 205 to the ground.

gas mileage is 10-15mpg i would guess.

engine idles @ 1800rpms and the engine rocks the car back and forth.

that said, once the motor hits 7000rpms it really kicks butt.

gear it properly and you have a real nice package.

turbo 12a makes better power, wider powerband, and better mpg.

but more crap to go wrong.

you will need a 13b peripheral port to make 300 @ the flywheel. perhip has a narrower powerband than bridge, but makes more power.

steve84GS TII

More porting means more revs to get the big ports breathing.More revs put more stress and wear on any engine.Plus you wont have much usable power down low,in the rev range you use to drive around town.
Sure, 250HP at redline is fun,but what about between 3-5K RPMS?....you cant floor it at every stop sign.....

To safely run over 8500RPMS,youll have to run carbon apex seals,which dont work well at lower RPMS and are somewhat fragile....and ceramics are expensive.

Thats the great thing about turbos.While they might be technically complicated,the engine will behave like a stock engine when the turbo isnt going.So long as you tune and prep well,a 12A can survive a small/modest amount of boost,drive great at lower speeds and have a killer topend punch.

Nitrous is another alternative if you dont want to dabble in turbos.Youll get the same midrange/topend punch but without the complexity.Just be sure to prep the engine the same way you would with a turbo.

Eriks85Rx7

i dont mind the idling rough infact it almost sounds like it matches my driving style. I dont floor it at every stop light in fact taking to high rpms is whati enjoy alot ( yes every driver is like this) but it really doesnt bother me that much the reason im thinking about this was saving money i could get a bridge port 12a for about 1600 with race seals so it wouldnt be hurt to bad. How long is the engine life out of 12a bridge port? also which is faster ? Turbo @ 6-10psi or a Bridgey?

steve84GS TII

No doubt the turbo.
Even a higher output N/A engine will usually lose to a weaker turbo engine,because the turbo is making its power over a wider RPM range.
The ported N/A is flat on its face until the ports start breathing.The turbo makes power as soon as the boost begens,which can be as low as 3000RPM and can hold it all the way to redline,if the turbo is big enough.Thats why its called,"forced induction".The bridgey is relying on just atmoshperic pressure to feed it,and those big ports just wont flow until the engine is revving hard.

Basic rule of thumb,...."Its not peak HP that matters,its making HP over a wide range,that makes a fast car."

Eriks85Rx7

hmm i see your point. the bridgey with peak hp just seemed ideal to me because i hate how my car actually stops pulling after 6500k. you mentioned the turbo can boost all the way too. Its obvious the turbo is the better choice but at cost and simplicity the bridgey seems attractive!

81gsl12a

iTrader: (1)

boots the bridgey woooot wont last to long but it would be ******* gr8

Eriks85Rx7

lmao yeah i could just turbo the bridgey man kind of power would that be pumping 350hp?

81gsl12a

iTrader: (1)

tuned right should be more than that you can get 250+ with a stock port and a turbo if its tuned right

aussiesmg

iTrader: (1)

I raced my bridgeport 13b for 4 years with zero problems, and that's in Australia we run 12 months a year there. No power under 4500 rpm and peak at 9000, brat, brat, brat, I miss that car so bad...

steve84GS TII

Turbos arent neccesarily better,it all depends on what you expect from your car.Trust me,turbos can be a headache when working right and a nightmare when done wrong.
They do make making power easy,but many other systems have to be adressed to make safe turbo power,which is why many shy away from turbos.Put simply though,turbos and rotaries go together like peanut butter and jelly,which Im sure is why Mazda choose that route to increase the rotaries output.
The main advantage to going turbo,is that turbos adress the rotaries main weakness..lack of lowend torque....by utilizing one of its other weakness'....heat and exhaust pressure.Youll have power where it never used to be,down low.

You just have to learn how to manage the heat,fuel and tuning issues.This is immensly complicated by the fact that turbocharging a 1st gen means that YOU have to do all the thinking.Mazda never did the R&D required to make a factory reliable 12A carb engine.Sure, there is the 12AT,but its not readily availible here,and its EFI.Which is why I always recommend that turbo dreamers just do a 13BT swap.Yea its not as original as a turbo 12A,but what good is originallity when your engine is blowing up every 3 months,or you cant find anyone to tune your carb,or you cant find those eluesive 12AT rotors,ect,ect,ect,ect.....