What would be the best engine combination for a street driven N/A going into a 80 RX-7? Just looking for suggestions. I need to know all parts needed to build a good engine 4 port.

 

13b

 

street ported 13B with intake/exhaust not much else you can do for performance

 

Bridgeport 13B, fuel injected, with ignition control (Microtech or Haltech or whatever), quad throttles, light weight Guru internals, light flywheel etc.

Only thing would be price, but it sure would be fun.

 

Try finding some 13B NA rotors and rotating assembly from 89-91 RX-7. They are high compression (9.7:1) and couple of pounds lighter than the GSL-SE's. Then use some 12A side housings which are street ported nicely.
This setup should yield around 200-220HP easily depending on the port job. Then have a nice header and a good carb (perhaps a 48IDA) or go fuel injected.

 

Well, If you are talking The Ultimate NA Engine,

Why not go with a 3 Rotor Motor?!?!

Afterall, money is no object!!

 

Peripheral port. 'nuff said.

That's sort of a joke. I think they can be streetable (for some value of streetable) and you don't *HAVE* to hog the ports out as far as the Mazda Factory Race ones, even if that would be the fun way to do it. But I won't go and seriously reccomend people go that way for a street car.

*I* am building one for street use, but I've taken a long hard look at all the tradeoffs, and I seriously think that I can live with them. And I'm willing to pay the price of building a new motor if it turns out I'm wrong.



On a more mundane note, I want to see someone use Renesis rotors milled for 2mm seals. I think that that could be a pretty nice combination for an NA motor, plus the rotors anyway aren't too pricey.

 

Well if money is no issue, go with a Renesis! Who knows the potential of one of those with a good port job. But this is just if money is no issue!

 

Well, if money is *really* no issue, go throw money at Mazda until they make you something completely and totally custom.

... none of us exist in *that* kind of lack of financial restraints.

 

a hurley rotary 777 or 4 rotor, in my opinion.

side question; what is it about peripheral porting that makes the idle/low end so lousy? Is it the huge volume of fuel, the duration of the intake cycle, or what?

 

like this?

 

It changes the intake opening and closing timing. Same thing a putting a racing camshaft in a boinger.

 

4 rotor 12a....

 

which guys had that4 rotor going ???i cant find there site anymore, thanks

 

Define "ultimate". When you can define the parameters of what you *want* from the engine, then you can start to determine what will give that to you.

If you want good reliability and driveability while having a good silid kick in the pants, a stock 13BT will fill the bill nicely.

If you just want all out peak HP, a huge J-port will make even more peak power than a peripheral port, however longevity will be a problem...

 

Ew, that three rotor 12A has a functioning distributor cap on it. How vile.

 

It actually took not a small amount of effort to make it function and he was happy when he did not have to resort to something else

 

Oh I don't doubt that. I even considered something like that, before I figured out a way to direct-fire the plugs on a three rotor (20B).

 

Just bought a S5 rotating assy and -se rotor housings. Just looking for some 12a plates and I'm set.. Thanks for all the info

 

That sounds like a great setup. Make sure to port the plates really well (I don't mean super huge, but just really smooth and gradual).

Hehe, a dizzy cap.

 

I have an idea, i'm gonna try and throw two 12as together and see if it works

 

I'll programme 911 into my speed dial, one sec..

 

Thanks for all the help. Should have it running in 2 weeks