Richard Miller

The subject 1981 with 12a blown rear rotor.

I have not driven the car for years and would like to resolve this.
I know of many different options. but would like opinions of the group.

It can be a 12a or 13b I already have the gsl-se front cover

Looking for 140-200 hp

must be civil, I really dont want a bridge or PP. As fun as it may be!

not looking to win races but for the entertainment value.

sub 8 sec 0-60

No Turbo

Would perfer FI. but a good steetable carb is a consideration.

I dont want to have to rev the **** out of it all the time, moderate low end grunt is sought after.

In FB fashion I have no budget for fancy pro rebuilds.

I am leaning toward : FC 13b 6PI retaining stock parts and using stock ECU w/ Racingbeat exhaust.

must work in all weather, Snow and Heat

Ill add more as I think of it

bliffle

I always thought the best combo for that would be a 13b streetport with appropriate weber carb.

Scott1982

I had an 88 with the 13B - loved the torque/power of the engine and gas mileage was better than 12a, did not care for the car (or seats) or variable power steering. Cost and time are no issue? If they are, getting a 12a back in would be so much simpler I would think.

flight_of_pain

-se rotating assy in -se housings and 4 port irons with big ports. This i assure you is a recipe for fun. I know there are other 4port 13b owners that can chime in to say the same.


isaac

bstrange99

Here's your solution Richard. As a result of our MANY and LOOOONG conversations about what you want from your car, I woul sa you need the following......

6 port 13b with stock internals
Stock 12a transmission
Full racing beat street port exhaust (incl. the muffler)
2nd gen leading ignition
Stock trailing coil
Racing beat carb hat
GOOD nikki carb, possibly a sterling. (very dependable on both counts)
5 psi fuel pressure

This will put you in the 145-150 hp range. Very drivable, and still fun.

brandon davis

iTrader: (3)

Will a sterling carb be enough for a 6port? If so then you would have to have an adatpter plate made to mount it to the 13b intake manny whether stock or aftermarket.

2Lucky2tha7

iTrader: (3)

Yes, and I am one of them. Before my current street ported 4-port setup, I had a street ported 6-port setup and I can assure you that the 4-port is far better.

j9fd3s

iTrader: (3)

well to break it down further.

12a and 13b cost within $50 to build, 13b will make more torque, so look for a 13b.

in the 13b world, a steet ported 4 port will touch 180-200hp, but so will an FC 6 port engine.

4 port or 6 port i guess depends on what you have available, and how you want the car to turn out.

4port with a carb, is old school.

id be doing a 6 port, s5 engine, because thats what ive got lying around

brandon davis

iTrader: (3)

I made the choice to do a ported S5 13b motor. makes the most power stock N/A of the 13b. 160bhp

FirebirdSlayer666

iTrader: (3)

Well a budget certainly kills my N/A 20B idea. I'd say make yourself a 4 port 13B. Use your 12A irons, 13B housings from the SE as well as the eccentric shaft. From there you can use any 13B rotors you want(with the exception of the Renesis. You could get them to work but it would be more work than it's worth). I would probably use S5 N/A rotors for the higher compression(9.7:1) and they are lighter. PM Jeff20B about '74 Spec ports. You will find better results than a street port

Jeezus

iTrader: (4)

12a Irons
-SE housings
S5 NA Rotating Assembly OR RX8 rotating assembly
-SE oil Pan
Streetport

There you go. 200HP with bolt ons.

spottedfrog

question about 4 and 6 ports.

does the 4 port make more low rpm torque over the 6? and does the 6 port make more high end hp?

flight_of_pain

Yes and no, and yes and no. are we talking ported or stock?


isaac

TheRX7Project

iTrader: (3)

Question about "bastard engines". What intake manifold do you use when you have 12a irons and 13b housings?

FirebirdSlayer666

iTrader: (3)

13B intakes made for the 4 ports

flight_of_pain

im using an rx4 intake iirc, the bolt spacing for the carb is bigger but the bores are the same. 4 quick drilled and tapped holes convert it to nikki spacing. If you decide to go this route let me know and i can snap you a pic.


isaac

j9fd3s

iTrader: (3)

stock to stock, a functioning 6 port engine will make more low end and high end is about the same, 6 port is a little better, as its got more port area and timing.

once the 6 ports arent working, however, the low end goes away.

porting a 4 port has more gains than porting a 6 port.

j9fd3s

iTrader: (3)

74-75 ports basically ARE a street port.

FirebirdSlayer666

iTrader: (3)

It's a different shape port than a streetport. Jeff posted a thread about it but I don't remember a whole lot about them

Jeff20B

iTrader: (13)

You're right, you don't remember a whole lot.

'74 spec ports are like a small streetport. The intake opening is not changed and can allow for bridgeports if desired (I've never done any). Only the closing timing is changed; delayed a few degrees but not as far as a Racing Beat or Pineapple streetport. '74 spec is like a happy medium and gives better low end than a full streetport on the street for daily driver duties.

The next 13B 4 port I build will have an RX-4 intake manifold, jetted Hitachi and '74 primaries with streetported secondaries. Exhaust ports will close a couple degrees after T2 (for better overlap = more NA power) and exhaust opening is yet to be determined; either GSL-SE or US-spec 12A/T2; which ever gives best low end while not hurting high end.

brandon davis

iTrader: (3)

Jeff your posts make me speechless, i dont know the right word to describe your level of intesity towards the rotary motor.

Siraniko

iTrader: (13)

bstrange99

And your estimation would be?.....be careful. I may have proof and witnesses....

Siraniko

iTrader: (13)

feel free to prove it and be sure to read my sig

trochoid

iTrader: (6)

13B frankenrotor.. 12A irons, SE housings, S5 rotating assembly and the RE dual Weber dcd carbs for low end torque. Mild primary streetport, Judge Ito secondary port.