Different between American 12a housings, and JDM 12a housings???
 

I have seen some people include that they have JDM housing in there motor, when decribing their car...


What is the difference?


Thanx, Laterz, Andrew

Peace... :rock:

i dunno about the jdm ones, but the european ones have bigger ports, they were hot in imporved touring and the spec 7 classes until they were banned

mike

really??? Do they the same size thickness of metal on the outside of the port??? Cause they would be very desirable then, cause they can be ported biger then....



Whats about JDM ones?

I've seen a 6 port 12A motor that was supposed to be from japan

The 6 port 12A engine was introduced in 1981 for only the Japanese market on the RX-7, Cosmo and Luce. There was no increase in performance but better fuel consumption.

12AT reverted back to the 4 port configuration and was rated at 135hp.

the European spec had bigger ports, from memory about 10 degrees more, and was rated at 105hp and 106lb/foot of torque.

hmmm, *thinks about going euro*

just port yours same thing, why try to find a rare motor

Half of the exhaust porting is done for you already on the JDM housings. They're almost twicw as big if memory serves me right. Ari showed me the housings from my dead engine and the JDM housings he was going to use for my RP streetport 12A and, even uncut, they were noticeably bigger....:cool:

Back in the 80's Mazda used different port sizes/timing for different countries due to the various emissions requirements (lack of) in different parts of the world. European cars had more timing, more top end power. They are all the same now. My GSL-SE's 13B had a factory mistake on it which made my car unique. Somehow a European rotor housing got mixed in with the standard ones. One of my exhaust ports was physically larger that the other one. Of course I pulled the engine apart and ported it so the prblem no longer exists. Same rotor housing and exhaust sleeve. The cutouts were just a different size. Runs much better now:)

I found a picture of the differences in mine. Picture quality sucks.

Here was my solution to the problem. Port them!!! The car runs great now. Bigger, smoother intake ports, long primary exhaust, msd direct fire, cold air intake, S5 RX-7 intake manifold, light aluminum flywheel. Car runs mid 14's on the stock computer now! Can't wait for the Haltech.

You're using an S5 intake with only 2 injectors?

Yup. Plug the other two. I guess I could fill the holes and grind the inside of the manifold smooth but I do plan to use a Haltech later and will probably use 4 injectors when I do. Later plans call for a turbo.