I'm thinking about putting a 13B in my 80 RX-7. What type 13B is better? Older 13B of newer 13B. I want to use a carb..

Thanks, Steve

 

That Depends on what you want.

78 + Older:
4 port, High flow engines. High power,
Low Torque, Peaky HP Curve.
Old School design.

84 + Newer:
6 Port, Hi RPM Actuators, Slightly
less power potential, very broad and
flat torque & HP curve. Newer Design.

This is fot stock port 13B's - Carbed setups.
I am not going into details about porting, or Frankensteining the engines with parts from different years, or Forced induction.

Mind you, the rotor housing and end plates from
a 78+older engine might be pretty worn out by now.

 

Hey, I don't know if you guys have ever tried this or not, but I've heard that using 12a side housings with 85 gsl-se rotor housings makes a good combination and you're able to get a little more power out of it because the 12a intermidiate housing is has a bigger port. I was going to do that set up on my '84.

 

Never heard of it but it should work..

 

you can actually port the intermidiate housing a lot more than the 13b intermidiate housing. Now keep in mind that it would only work if you're using a carburated engine like holly or weber. Also the intake manifold must be the same as the '76 (the one that came with the rx4) because the pattern is the same. I'm not sure if the manifold for the '85 se would fit though. I would also go with the second gen oil cooler, I think it cools better. I believe that the '82-'83 also came with that front mount oil cooler.

 

look dude...it will work. use a core 84/5 13B and a core 12A engine. use shaft and rotors as well as balancing assembly from the 13B and the side plates from the 12A. streetport the **** out of it and it is pretty nice. i finished mine a couple of months ago and ran it the other night at the track...full tank of gas, stereo system w/subs, all kinds of **** in the hatch and passenger seat....14.8 secs. i thought that was pretty good since the SE i had before with the same exhaust and dellorto ran a 15.1 at best..... and yes it was ported. to answer the other guys question, yes the bolt pattern is the same. order the racing beat lower manifold and it works fine(if you already have a dell ) if not the holly setup is probably the best option. i am thinking about selling the dellor.....well maybe not. i'll just buy the holly and see if i can get better times. well, never mind, i nedd to get my 3rd gen running again. anybody want to buy a motorcycle?

 

oh yeah, that guy was right about using 82/3 radiator and oil cooler. have them cleaned thoroughly and no problemo. i had to get rid of the water cooled cooler...which is a very wise thing to do on a modded motor. also either heat and bend the mount (ooooh...i forgot, you'll have to trim one of the corners a little. really, just a little, so don't fret it), or just buy the mount from racing beat. be sure to use the SE oil pump too, it flows the same as the mazda comp pump...just doesn't have the hardened rotors inside. while you're at it, get the higher, street pressure regulator. everything helps when it comes to these things.