bighroder

I want to know about how much horsepower does an early 12a motor make stock and what is a good goal to reach upgraded? I am not going to be using it in a rx7 but actualing in an old v-dub. what is the redline and does this motor have any real computer that hooks up to the engine to run? thanks zeth

85 FB

IIRC, the 12As made about 115HP, I think. Redline starts at 6 or 7k. That's all I can really offer.

Depends on what you mean by upgraded. Turbo? Yeah, you can get some serious power out of them if you know how to do it. Do some searching around, there's a lot of threads in here that focus on power mods, mainly a turbo. And, the 2nd Gen ignition setup.

bad 83

iTrader: (3)

The 83-85 12A's had the lightest rotors. As far as hp, they were advetised as 105 at the crank. That would be about 85 or so to the wheels. With external NA upgrades only, you may sqeeze another 30 or so. With a blowthrough setup, at 12 psi, you might tap about 200 or so at the rear wheels. Open that thing up, nice bridge port, and blowthrough, more than you can handle.

orion84gsl

iTrader: (5)

To add to that, 12A's are carburetted, aside from the J-spec 12AT, so no computers involved. With a good streetport and a properly sized carb, and a decent exhaust you should have no problem reaching 150HP+. A turbo on top of that will make the car fly. Stock numbers are 100HP and 105 Ft/LB torque. Redline is 7K, but also with porting you can move that up some.

diabolical1

iTrader: (3)

welcome to the board.

how old is old?

it appears the really old 12A's (6mm) were rated at 130 BHP, while the later pre-Rx7 3mm motors were rated at 120. of course, then there's the ones in the Rx-7 rated at roughly 100.

redline will depend on your final setup (breathing mods). i suppose 150 and up is the mark if you're not going to fool with forced induction. no computer needed.

bighroder

yeah i realy want a "reliable setup", most people on other forums say that boost and reliability are 2 oppisite ends. If you are asking how old is the v-dub it is 1968 standard beetle being turned into a baja. I dont have any emission test to pass in MI. so i dont have to worry about that. And if this works out and I like the motor I might be putting one in a ghia(2 seat v-dub, realy old for those who dont know).

just a couple more questions on the rotary:

what sort of engine life is expected for these motors, NA?
what kinda fuel mileage do you get with 150hp?
this is probably cominly asked but where is your powerband at, roughly in these 12a's

trochoid

iTrader: (6)

Stock, 101 hp, 105 lb/ft at the flywheel. Streeptported, headers and a well tuned aftermarket carb, 140-150 whp. NA engines have been known to go well over 200k without a rebuild, normally life is 150+k. Mileage, that depends on porting, carb and lead foot. I can pull 22-24 mpg out of my 1/2 bp 12A on the highway. It can also go as low as 8.5 in town, heavy foot in the winter. Rotarys have a very flat torque curve from around 1500 rpm to 6500 on a stock port, higher on a streetport/bridgeport.

bighroder

this may sound stupid, but do rotary engines have valves? and do you have to run premium threw the engine or just unleaded? How much does it cost to have someone street/bridge port an engine?

thanks zeth, and sorry for asking so many questions.

ChaosAura

8.5 actual miles, or miles on the odometer, depending on your winter, that makes a big difference

85 FB

No valves, those're only in boingers. Unleaded fuel.

Cost for a S/BP, depends on who you go with. I've seen them start at around $200 and go up, and I believe some members do it themselves with a template and a Dremel too.

-xlr8planet-

iTrader: (3)

My euro model rx-7 1981 came from factory without any emissions control and rated at 115 hp

bighroder

DO they use reeds like in snowmobiles?
And can you by templates to follow, and do them yourself, where would i buy one?
thanks zeth

85 FB

dp, see below

85 FB

What are reeds?

For the templates, Racing Beat and Mazdatrix sell them. Also, check out NoPistons forum and check out a guy by the name of Ito.

See if these search results help you with porting questions.
https://www.rx7club.com/search.php?searchid=4485971

-xlr8planet-

iTrader: (3)

I think he believes it works kinda like a 2 stroke engine

mikewoodkozar

Our aging cars without the proper maintenance are probably not putting out what they were from the factory in the 1980's. I know when i first bought my car it was a drag to drive (real sluggish). But it came around real quick and now it feels like a whole different car, lol

Vashner

A skilled driver can still burn a muscle car on a tight street race with lots of turns, in a stock street race. Hp is not everything....

You also have to consider the time at which 12a was designed. All HP was down. Even Vette 5.7 was gimped. 2 oil crisis and emissions issues. It was the dark era of HP per cc.

Another reason Mazda kept bumping up the power as times changed.

diabolical1

iTrader: (3)

i was asking how old is the 12A you're using? because outputs and expectations can vary slightly depending on what you start with or some parts combinations.

mikewoodkozar

That is true, i have smoke many a vette in the little 7

bugman1973

84-85 had lightened weight rotors. that had more hp than stated. i had an old vw that had about 120hp it was really torqey but my rx7 will blow it out of the water. the things your going to have to worry about is where is the radiator going to go how are you going to keep it from over heating. go to CB racing they have a fifth gear up grade for the bug tranny. have you tried looking on thesamba.com they have quite a few rotor heads on there. and on how they work check this out. http://www.youtube.com/watch?v=oGrD7FTFLJc have fun with your project

bighroder

yeah i am a member of thesamba forum, there is quit a few people telling me that i shouldnt do it.

one more question; ROUGHLY, how much money will it take to make a rotary 12a make about 120hp, without nos, turbo, or any thing that isnt NA. And what are the parts to upgrade that make this happen?, if all the work was done by me?

bugman1973

have you boughten a 12a yet or are you still trying to find one? which one is it? how many miles does the said engine have. and it CB performance not racing. which trans axle do you have? do you have the adapter plate yet? and all you need to get 120 hp out of a 12a is barely anything just by the engine and maybe swap the carb. your going to have a hard time with the throttle linkage but id just buy one that is for say a sand rail thats just longer than normal. and run some kind of sleeve over it so you can "turn it" so that it matches up with the carb you chose. i almost did a similar swap my self a few guys on here have done it. but they used 13b's go look on youtube youll find quite a few old bugs running them.

bugman1973

like this one its got a 12a in it http://www.youtube.com/watch?v=jE8uyyn4DQY

http://www.youtube.com/watch?v=woqiFrnZqvE

slate84

i love those old ghias, my grandpa had one and i thought it was amazing

bugman1973

i had one as well along with about 5 beetles. fix the small stuff well for profit ive made any where from $100 profit to $3500 profit. bighroder we need some help here we are missing crucial pieces of the puzzle.