I want to bridge port my 12A, put a carb on it, ignition, suspension the works. Can i reuse the same rotor housing and port myself? or are new rotor housings the only way to go? Where would i get lightened rotors..etc.

 

From what I understand they don't make new rotor housings for the 12a more. Someone please correct me if I'm wrong there.

A lot will depend on the milage on the current housings. If they are pretty high they might be pretty worn out and out of spec.

 

They don't make them. Make sure the rotor housings are up to spec.

 

Head over to www.nopistons.com and check out their engine building/porting section. There is a wealth of information on this topic over there, and some of the top builders hang out to answer questions.

You probably won't be able to tell if the housings can be reused until you actually tear the motor down and get a look at them...

 

bingo. post pictures if there's any doubt, someone can tell you if its good or not.

 

dont expect much

The engine might start fine off the key, run like a dream, make good power, then you tear it down and the housings are 3mm of chrome missing on both running edges.

I was really lucky to get my housings, I got one of the last sets my supplier had

 

What? When did they discontinue 12a housings?

Mazdatrix still lists them as being available:
http://www.mazdatrix.com/b1.htm

You won't be able to know if they're reusable until the teardown, but I'm always reluctant to reuse housings, especially on a motor which will see more... spirited use. Ported engines are more likely to inspire you to drive it hard, and starting with half-eaten rotor housings won't help matters much.

You can check Atkins as well, I believe they have some housings available. I don't know if mazda still provides 12a housings through the dealer, but if you're *REALLY* stuck in the end, I know a place that can replace the chrome coating with a Ceramic-compound (Cermet) coating and recondition the housing. I can't speak to their quality, though I've heard good things, they haven't been around long enough for anyone to teardown an engine built with these newly cermet-resurfaced housings. Search up JHB Engineering in Google, look for a place located in Canada (I think the site's a .com though)

Jon

 

they are NLA but there is still many new ones out there.

 

Thanks fellas...those are all things ive had in thought. makin sure im to retarded! im not tearin it down yet runs to good. i have to fix my protege so i have a daily driver.

 

Just a thought, but why bother with the 12A? A street ported 12A is going to make around the same power as a factory 13b?

IMO I'd shoot for a late 89-92 13b they are fuel injected and have 160 factory HP VS the 12A's wuss 100. Toss on a header and do the exhaust and intake and you'll make around 180ish fw hp. Much more than a mildly ported NA 12a.

NA 13b's are pretty cheap, esp if you go the JDM route. And if you have deep pockets and want real power go for the TII swap.

Or if you like me throw a v8 in there and call it a day...

 

Sry Im a rotor enthusiast I will never throw a V8 in an RX7. no offense to ppl who do do it, just not my style. I have a NA 13b out of my 87 RX7, but idk what i wanna do with it yet. I like having the 12A in it. I wanna see what it can do!!

 

None taken, I love these little motors too. I'm not about to get in the rotary VS piston debate on an rx-7 board.

More power to you... Maybe you can teach us all a thing or two with your little 12A :cheers:

 

im looking at the same route iv torn 8 motors down for the cause
few things tho u should look into for a brige port or half brige is to rebuild with the 10,000rpm mods and upgrades since a brigy can make power past 8k

few things i can re call to help would be
3 window bearings to help incress oil flow
moded or new oil pressure regulator
maybe hardend stat gears
have the rotors clearenced and the rotating asembaly balanced
i think it was carbon seals for the over 8k
upgraded oil pump like a gsl-se one
prefbly best housings u can get ya hands on
upgraded clutch and light flywheel
maybe a 48 ida or a holly carb
i might be missin a fear few things

 

oh a free flowing exhaust
then thats running u some cash right there
13b might look like a pretty idea

tho i have **** load of parts why not use them lol

 

awesome thanks for the tips...where would I go about getting those upgraded parts? to me for a RX7 money isnt an issue, build it once build it right. Will the transmission and rear end hold up with all that power?

 

Racing Beat, Mazdatrix and Atkins sell the parts needed to upgrad for high rpm operation. RB can also perform the rotor clearancing and assembly balancing. Mods will nearly double the build cost over a full rebuild kit, assembly costs not included. You will also need the supporting intake, carb and exhaust mods.

 

I talked with Tim from MazdaComp last Friday after I saw some posts here regarding the death of 12a housings. While he did confirm that some of the 12a parts are being discontinued (there are 13b parts that are interchangeable) housings and rotors and the like are still being made.

 

from what Mazdatrix has on their website, the S1 rx7 12a rotor and side housings are no longer available since Mazda stopped making new ones. Mazda still makes new housings for S2 and S3 12A but I would get that in the next three years those will be history as well.