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-   Rotary Engine Building, Porting & Swaps (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/)
-   -   12a engines? (https://www.nopistons.com/rotary-engine-building-porting-swaps-55/12a-engines-65464/)

damo3001 04-25-2007 04:20 AM

hey i was just wondering what are all the 12a type motors out there.i know 13b's have like a 6port engine and 4 port and turbo but i am a bit blank on 12a's and i want to know all the 12a's and if they can make decent power?thanks

Lynn E. Hanover 04-25-2007 07:02 AM


Originally Posted by damo3001' post='869462' date='Apr 25 2007, 02:20 AM

hey i was just wondering what are all the 12a type motors out there.i know 13b's have like a 6port engine and 4 port and turbo but i am a bit blank on 12a's and i want to know all the 12a's and if they can make decent power?thanks



A 4 port with a "J" bridge port, 244.8 HP at 9,400 RPM, through a Weber with 36MM chokes.



Lynn E. Hanover

damo3001 04-25-2007 07:17 AM


Originally Posted by Lynn E. Hanover' post='869465' date='Apr 25 2007, 09:32 PM

A 4 port with a "J" bridge port, 244.8 HP at 9,400 RPM, through a Weber with 36MM chokes.



Lynn E. Hanover



what other 12a motors are there??and what streetable power can be obtained?thanks

Tom93R1 04-25-2007 01:32 PM

12 motors in the US were all 4-port. The major differences were in the rotor housings and whether they routed EGR gasses into the mid plate or dumped that out beneath the exhaust ports. There were also some intake port differences, some had large ports and others had small depending on the years.



The other difference would be some of the early 12a motors had dual dizzy's, thats all front cover differences.



Stock they were all in the neighborhood of 100hp flywheel. Their tiny exhaust port and be greatly enlarged and with some intake porting there is alot more power to be had.

heretic 04-25-2007 06:24 PM


Originally Posted by Tom93R1' post='869514' date='Apr 25 2007, 10:32 AM

12 motors in the US were all 4-port. The major differences were in the rotor housings and whether they routed EGR gasses into the mid plate or dumped that out beneath the exhaust ports. There were also some intake port differences, some had large ports and others had small depending on the years.



To be fair, there was only one 12A with EGR. It was a one year only California model.



The ports that you think are for EGR are actually for the air injection system.



The funny thing is, some thermal reactor type engines also had the port under the center intake ports. It didn't go to anything, and the stock intake manifold actually left it hanging bare and wide open, but they bothered to cast and machine it all the same.

diabolical1 04-25-2007 11:51 PM


Originally Posted by damo3001' post='869462' date='Apr 25 2007, 01:20 AM

hey i was just wondering what are all the 12a type motors out there.i know 13b's have like a 6port engine and 4 port and turbo but i am a bit blank on 12a's and i want to know all the 12a's and if they can make decent power?thanks

there is a factory 12A for every 13B type you mentioned. "decent" power is completely subjective, but for what it's worth, aside from the novelty for collection, neither the 12A Turbo nor the 12A 6-port have anything over the 12A's we got in the US.



also, i know Lynn is a grown man and can speak for himself, but you might want to look around the forum and see the info he has shared with us and maybe calm down next time. i sensed a little bit of snottiness in your response and i just think he may have misunderstood your query. if it was not snotty, i apologize for my misunderstanding, and disregard my comment with no foul.

damo3001 04-26-2007 05:25 AM


Originally Posted by diabolical1' post='869592' date='Apr 26 2007, 02:21 PM

there is a factory 12A for every 13B type you mentioned. "decent" power is completely subjective, but for what it's worth, aside from the novelty for collection, neither the 12A Turbo nor the 12A 6-port have anything over the 12A's we got in the US.



also, i know Lynn is a grown man and can speak for himself, but you might want to look around the forum and see the info he has shared with us and maybe calm down next time. i sensed a little bit of snottiness in your response and i just think he may have misunderstood your query. if it was not snotty, i apologize for my misunderstanding, and disregard my comment with no foul.





nah no worries no snottyness ere just had to rite it quick because i had other stuff i had to do yesterday,thanks for your help..i just wanted to know this because i am from australia and am thinking of buying a rx3 that has a 12a in it and i just hoped they didnt make a 6port 12a because i own a 6port 13b and its guttless as all **** and not many rotary places around here make any decent power out of the 6 port.thanks all for your help..

RE_TurboFB 04-27-2007 12:03 AM

Hell a 12a belts out 100HP at the flywheel. the S4 13B 6 port had 147HP at the flywheel I think, and the S5 13B 6 port belted out 160HP at the flywheel. the stock 12A is gutless as all hell!!!



www.Racingbeat.com claims that a 12A can make 250 - 280 reliable non-turbo HP I think they where using weber 52 doc carbs?

j9fd3s 04-27-2007 10:30 AM


Originally Posted by damo3001' post='869598' date='Apr 26 2007, 03:25 AM

nah no worries no snottyness ere just had to rite it quick because i had other stuff i had to do yesterday,thanks for your help..i just wanted to know this because i am from australia and am thinking of buying a rx3 that has a 12a in it and i just hoped they didnt make a 6port 12a because i own a 6port 13b and its guttless as all **** and not many rotary places around here make any decent power out of the 6 port.thanks all for your help..



well if you're in austrailia, thats a little different.



82-85? they did have a 6 port 12a, its carbed



83-85 they had a turbo 12a. it used lower compression rotors, like the 86-88 turbo's. it also has smaller ports. but its turbo, so you can turn the boost up.

Jeff20B 04-30-2007 01:42 PM

The 12A turbo rotor housings had larger ports than US spec (closed later but probably opened the same). My friend purchased a set for an engine rebuild a few years ago. I recently upgraded the carb, manifold and exhaust on the car and got to look in the exhaust ports. They did look bigger. https://www.nopistons.com/forums/pub...IR#>/smile.gif



It was in an '84 automatic model with overdrive. It still passed emissions even with bigger exhaust ports. https://www.nopistons.com/forums/pub...IR#>/smile.gif


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