1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

few question about a 12a 6 port engine

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Old 11-09-04 | 09:41 AM
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From: Pensacola
few question about a 12a 6 port engine

1. how much more KW are they in comparison to a stock 12a?

2. how much more fuel do they use, like considerably enough for you not to make it a daily?

3. is it really worth getting these engines?

cheers
Old 11-09-04 | 09:51 AM
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Where can you get a 12A 6 port???? They were never produced. The only 12A 6 ports engine that are out there are custom made.
Old 11-09-04 | 10:09 AM
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actully we have one in stock for 900 complete long block. Made 135ps(which i think is 138hp) Very nice set up. Susposidly has a better carb and manifold then the older 4ports. As for gas econ. I dont know. I do know my 13b 6prter made 22-25 on the hwy not playing. My 4 port turbo engines though. HEHEHHE yea 12. Take care

Shane
Old 11-09-04 | 10:15 AM
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was a JDM engine..so probably is custom..

but yeh anyone have experience with these babies?
Old 11-09-04 | 12:09 PM
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why are you saying it has to be custom? im sure you can import these bad boys (if you can locate one, sounds like rotaryworks has one at his shop)

i doubt that gas mileage suffers that much, you're actually going to get better gas milage while the 5th and 6th ports are closed, then when you open it up, im guessing from 3500-4000 rpms the ports will open up. So if you were to wire open the actuators or if you have your foot in it constantly i can see you getting worse mileage.

honestly i think it would be better just to streetport a 12a, you wont get the low end repsonse you will with a 6pi but its probably cheaper and easier overall. (although 900 bucks isn't bad)
Old 11-09-04 | 12:16 PM
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I think mazda actually did make a 12a 6port from the factory... I think it was used in a cosmo or something...

edit: check down at the bottom.

http://me.a-spec.ca:6001/Rotary/12A.html
Old 11-09-04 | 12:25 PM
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From: chatsworth,Ca.
in answer to your questions......

1. how much more KW are they in comparison to a stock 12a? less than a normal 4 port 12a

2. how much more fuel do they use, like considerably enough for you not to make it a daily? they use less gas than a normal 12a because they are way slower!!

3. is it really worth getting these engines? **** no!!! those engines suck, i know from personal experience!!!

the intake ports are tiny!!!=no power
the center housing has a big chunck of metal sticking out of it so you HAVE to use the restrictive tiny exhaust header it comes with

the only cool part of the motor is the black air cleaner cover that says 12a 6 port on it, bad ***!!
Old 11-09-04 | 12:40 PM
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exactly... but if you do get one.... don't bother eating cheese anymore 'cause it's not worth it
Old 11-09-04 | 04:21 PM
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From: Pensacola
Originally Posted by 680RWHP12A
in answer to your questions......

1. how much more KW are they in comparison to a stock 12a? less than a normal 4 port 12a

2. how much more fuel do they use, like considerably enough for you not to make it a daily? they use less gas than a normal 12a because they are way slower!!

3. is it really worth getting these engines? **** no!!! those engines suck, i know from personal experience!!!

the intake ports are tiny!!!=no power
the center housing has a big chunck of metal sticking out of it so you HAVE to use the restrictive tiny exhaust header it comes with

the only cool part of the motor is the black air cleaner cover that says 12a 6 port on it, bad ***!!
you serious?!

why the heck does mazda call it a "development" then
Old 11-09-04 | 04:25 PM
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From: Pensacola
oh and reason i asked about these engines is coz im intersted in buying a car with it.

car details:

series 2,
re trimmed interior,
locker,
extracters
electronic igniton
brand new tyres on neals wheels,
12a 6 port 5ht and 6th ports wired open. copper from intake removed


pics

Old 11-09-04 | 04:33 PM
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That car looks awesome. It seems like we are having conflicting information here. I know nothing of the 12A 6pi but that car looks awesome. Do you have any other pics? Specifically of the engine bay.
Old 11-09-04 | 05:54 PM
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From: chatsworth,Ca.
Originally Posted by timmya2
you serious?!

why the heck does mazda call it a "development" then


uhh, they should call the 12a 6 port a setback!!! because thats what it was!!!


**** your an aussy, get a 12a turbo, with extra cheese!! that will be a fat ride
Old 11-09-04 | 08:31 PM
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I owned a 84 Cosmo (basically what Mazda called its rotary powered 929) which had a 12a 6 port carby and a 3 speed auto.

The car before that was a 85 Series 3 RX7 with a 12a 4 port carby and a 5 speed manual gearbox.

It is hard to compare the 2 (performance and fuel economyy ) since one was a 1050 kg sports coupe and the other was a 1300 kg 4 door limo although I do not believe that the 12a 6 port is a power house compared to the 4 port.

The primary ports on the 6 port were more conservative (to produce more torque at lower revs) which was more suited to the type of cars (passanger cars like the 929) that these engines powered.
Old 11-09-04 | 09:12 PM
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From: Napier
Originally Posted by 85rotarypower
Where can you get a 12A 6 port???? They were never produced. The only 12A 6 ports engine that are out there are custom made.
The 12A 6-port was an option on the JDM series 2 RX-7's, they also made an appearance in the HB Cosmo. I would be suprised if they were even halfway common in the states, but in NZ and Aust they are relatively easy to find.

I had a 12A 6-port which I sold for about US$50 a while back, had shot oil seals. Virtually no gain in power over an export 4-port engine, but what you need to remember is the R5-Black 12A as used in S1 & S2 JDM RX-7's actually had very small ports and the 12A 6-port was designed to provide more torque and power without sacrificing fuel economy or emissions. It achieved this quite well, but still not a serious contender for most powerful engine ever
Old 11-09-04 | 10:11 PM
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my book said 135ps 6pr t12a, 130ps on the 4port. The one here at the shop has a flywheel on it so it must of been out of the Rx7 s2, pretty cool engine thou. I guess since it is so rare in the states.

Shane
Old 11-09-04 | 10:30 PM
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i say hook it up with a 12a turbo and ill be happy
Old 11-10-04 | 12:57 AM
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yeah its basically a novelty type thing to have one in the us, i guess if stock type driving is what you're looking for then what the hell, go for it.

But if you want more power eventually look at it this way,

hard to port it well, a 4 port can be ported much bigger and better
harder to turbo charge, (well not exactly harder but the gains aren't as good)
and you can't even add headers as rob said

so its just a novelty engine, i would be proud to own one for sure, hell id probably make vinyls saying 12a 6 port or something, but i wouldn't be takin it to the track...
Old 11-10-04 | 01:07 AM
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From: Napier
Originally Posted by mcnannay
so its just a novelty engine, i would be proud to own one for sure, hell id probably make vinyls saying 12a 6 port or something, but i wouldn't be takin it to the track...
It's amazing how one countries junk is another countries treasure. I'd kill for a genuine GSL-SE oil pan, whereas I wouldn't think twice about throwing away a 12A 6-port if it wasn't running.
Old 11-10-04 | 11:23 AM
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From: chatsworth,Ca.
Originally Posted by Jon_Valjean
It's amazing how one countries junk is another countries treasure. I'd kill for a genuine GSL-SE oil pan, whereas I wouldn't think twice about throwing away a 12A 6-port if it wasn't running.

isnt that the truth!!
Old 03-01-23 | 10:39 AM
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Reviving a dead post, But i wanted to document this information since i have lots of experience with rotary engines.

One of my Rx-7s had a 12A 6-port in my 1983 GSL-SE.. Before that I had the 6 port in there I had a normal 12A and a 4bbl holley and a Turbo kit, That thing would do wheelies when racing if your not careful. But the turbo took a dump and blew all the oil out the exhaust one day when I was racing a Supra at 120mph. the engine fused the rotor to the eccentric crank on the way to friends shop. I later sourced a 12A 6-port (which BTW were supposed to have a turbo in them, mine didn't for some reason) But we rebuilt it and expanded the bridge ports on the extra 6 port housing ends. My 12A 6-port would run past 8K rpm for about 6 seconds until i would shift and every time it would stay beyond the 8K limit. I had literally blown apart the clutch 3 times form the excessive RPM. I then put a solid brass 4 puck digital race clutch in and it lasted longer (2 months) but eventually also exploded that disc. when i rebuilt it I took out the variable port actuators, and the variable port valves on the 5th and 6th ports. and then added a new custom exhaust, I cant recall if it was from racing Beat or mazda trix. Also ground out the exhaust ports. I would shoot flames out from under the car between shifting. I also put a 3rd Coil in and ran the 2 lower plugs direct to the coils which then got me 3 sparks per combustion since it was electronic pulse on the ignition coils the direct coils would fire twice and the secondary would fire once of the distributor at the end to get max fuel burn possible. It didn't really wear out the plugs any faster. I drove it cross country and raced many other cars. It was a monster of a little engine. Until one day it got towed away and i never saw it again because i didn't have money to bust it out of car prison. I don't know what every happened to that bad boy but i'm sure whoever got it had no idea what was going on under the hood. The gas mileage was not that great but i also loved to drive it over 100mph everywhere i went( which is one reason i couldn't pay all the tickets) I even raced Val Kilmer in his Volvo one day, when i hammer into 3rd it would chirp the tires passing him on the freeway. iI just kept pulling the faster it went, i actually was afraid to get to the 15K mark and blow an apex seal or bend one as it passed my expanded exhaust ports. I never upgraded to the hardened and wider seals.

One thing you need to keep in mind on the 12a 6 Port if you ever find one. Is that it actually has what would be considered an additional "bridge port" on the front and rear housings. Thus when worked properly you can achieve a lot of power and high rpm.

I also would rebuild them all the time. I still remember how.

Warm regards fellow RX-7 enthusiasts.

Old Fan




Last edited by Rx7-fan; 03-01-23 at 12:00 PM.
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Old 03-06-23 | 06:21 PM
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I'd imagine it was more of a "test-run" for the 13B NA 6-ports... My buddy has 12a 6-port waiting for me. It's got the lil actuator solenoids too, and its carb'd. I just like it cuz you don't ever see 'em.

Last edited by fbse7en; 03-07-23 at 12:16 AM.
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