dirty86

sooner then i thought but i think the engine swap is going to happen

this is my dilema what should i do
all opinions wanted

I have a 12 right now i JUST bought headers and exaughst and put it on,

so will a 4 port 13b work with the 12a headers ( i read somewhere a 4 port is half 12a and half 13b)
and does a 4 port put out as much HP as a 6 port??

is my assumption right about the 4 port being a mix of 12a and 13b?

Is there anything special needing to be done for a 4 port? Like: will it go together no problem (will the plates jsut bolt up) what flywheel and clutch do i use?? on a 4 port??
same about tranny which one?
same with carbs do i shop for bigger 12a carbs or 13b carbs or what

I know nothing about this idea all information appreciated

THANKS!
-Travis

Lotus00

well you are part right on the 4-port being a mix of 12a and 13b. there were 4-port 13bs made, but they are the pre-rx7 ones. you can make a 4-port 13b by using the cast iron pices from a 12a. I think the 13b pices have to be from a certin year, cause the water seal grooves changed or something. someone else can explain this better.

I read that a 4-port 13b can make more power than a 6-port, but I have no idea why.

im not sure if the 12a header will work on a 13b, but I remember reading that you can oval the bolt holes and grind (5mm?) off the inlet to the headers to make it fit.

dirty86

any one know what year???
of 13b

DriveFast7

iTrader: (1)

12a headers won't fit 13b. you'd have to cut and weld the headers to fit the longer 13b block

13b 4port puts out slightly more power than 6 port.

mazda made factory13b for ports in REPU, Rx4, Cosmo 74-78. you can make your own by mixing and matching pre 1986 engine parts. in 86 water seal moved from rotorhousing to side plate.

anything special? yes plates just bolt up. counterweights neet to match the rotating assembly you are using (rotors and eshaft). flywheel can be either 215 or 225mm, clutch must match flywheel.

1st gen tranny works great

if you want the most potential of power, use a bigger carb, one for a 13b. 48mm+ for 2bbl.

Good info:
http://mazdatrix.com/eng13bsp.htm

kleinke

Turbo engines are all 4-port, such as FC turbo II and FD engine.

brianw

I was told that the 84-85 13bs were 4 port. Was this bad info?

DriveFast7

iTrader: (1)

Yes. They're 6 ports and fuel injected!

brianw

thanks drivefast7. How hard should I try to get a 4 port? Are they really ahrd to come by and do you know how hard it would be to setup a 13b efi in my 83? I have the leak of death going on in mine and it's really stating to get bad so I'll be getting a motor to rebuild and maybe port soon. I figure why not step up but I'm not sure how involved it is.