Bench racing for my 12a :)
 

Hey ya'll,

I'm pretty new to the forums, got an 85 with the 12a a few months ago and am finally feeling pretty good about driving it around, so never being one to leave well enough alone, I figure she needs a little love in the horsepower department, right now its completely stock, smog stuff and all. Here's what I think I would like to end up with:

-Sterling Nikki
-polished stock intake
-mild street port (someone posted not too long ago about big ports on the secondaries and just cleaning up the primaries to retain near-stock starting and idling, any thoughts there are welcome)
-RB or similar long primary or true dual exhaust (with LOTS of muffler, don't want super-loud)
-Smog pump and rats nest delete
-Keep AC (need it if you get caught in the rain around here!)
-E-fan conversion of some kind
-some kind of ignition upgrade, just for a little better economy and better reliability (thinking coilpacks, but something off the shelf would be great)

I guess I'd like to turn this into a weekend driver and autocross car, I want rock solid reliability, a nice wide powerband, and good enough manners where someone else could start and drive it. Power-wise, I'd like to see around 180-190 at the wheels with good tuning.

So is this the way to go? Anything I should add to the list, or anything on the list that isn't necessary? Or am I just out of my frickin mind?

THANKS!

Your not far off the mark with that list. Those numbers will be difficult to get to on a 12A, very few carb'd 13B's actually see those numbers with just a streetport. Check out Hyper4mance2K's exhaust thread to see one that has. I've got a 13B with mild porting on the primaries and more aggressive porting on the secondaries. With the mechanical secondaries of the Sterling it makes it easy to cruise around smoothly and use just a little more gas than the 12A, but I can open it right up with a push of the throttle. With the RB dual exhaust you won't need to add any more mufflers. It's quiet as can be unless your ripping through the RPM's, in which case it sounds phenomenal. I will however advise against adding much power until you've addressed the suspension, steering and braking components. www.re-speed.com will be a big help in this area.

Agreed completely, but suspension and stuff is a whole 'nother can of worms. And that re-speed stuff looks like great quality equipment.

Sorry for my ignorance, here are a few questions: I've seen the full dual RB setup, but I thought that was just for the FC. Or can it be made to fit the FB?

Also, is there another porting option that might get better power without getting too wild? Like what's the next step up?

And I'm sure the sterling idles nice and low, and is easy to start?

And one more thing I meant to ask in the OP, are there people out there who can do a good quality porting job, like I could ship parts to them to have them ported? Not that I'm above doing it myself, but especially with fresh 12a's becoming rare, i'd really hate to screw something up. Be great if there was one in the Nashville area!

https://www.racingbeat.com/FRmazda1.htm. Not exactly a true dual system since it collects before the muffler. It's more of a long primary system.

You could go half bridgeport, or a full bridge. These make more power but may shorten the life of the engine and isn't as streetable as well as having a powerband

My engine fires right up with the Sterling. Never had any issues.

You'll have to check the southeast forum for engine builders local to you, but there are many that can do it.

I don't think a 12a, no matter the porting, can get to 190 whp without boosting from
a turbo or supercharger.

With the mods in my signature my stock port is able to put down 134 whp on
a dynojet as an example. If I SP it I might get 20 whp conservatively.

agreed. i think 130-135hp depending on a few factors is pretty close to as much as you can make on a stock port engine.

and if the NASA performance touring rulebook is right a Peripheral Port 12A will only do 225rwhp...

so 190 is maybe bridgeport territory

dj55b is pushing ~165whp in his 12a powered monster. 47mm Fuji racing ITB's, Megasquirt, street port, and a bunch of other stuff. It's fast as hell.

Damn, so prolly no big power for me :(. I guess I'll just try a few things and see how they turn out. I found a guy selling the complete engine and tranny with 30K miles from one that he swapped a v8 into for a song, I figure I'll drop that engine and tranny into my car and start figuring out whether my engine (167k miles) is even worth messing with. If not, a 13b is likely in me distant future :).

at 167k i rather enjoy the miles you got left while retaining it as stock.

keep in mind that its not all about peak hp. the rotary has a wide torque band too, and its in a light car.

going from 100hp to 150 is a 50% increase, it makes a big difference

I'm a little more than that now :) I'm getting 10km/h quicker on the straight aways at the track with my new pressure regulator and a bit more tuning :)

the hp #s listed here r interesting. guess the dyno i was on during a meet with the crossroads guys must have been wrong. it claimed 191 from mine. should have known it wasn't right.