I never had a first gen or anything nor have i had a 12a motor ect. I just inquired a SE and im wondering the difference between s4 n/a 13b and the SE 13b. i know the obivious differences like injectors and such lol. Are the irons and housings interchangeable?

 

quick answer is no

http://foxed.ca/rx7manual/manuals/Training%20Manual/

 

The s4 engine controls are much more advanced than the s3. The s3 still uses a distributor with two batch fired injectors. The s4 uses staged sequential fuel injection with a firing order that is synchronized by the crank angle sensor. It also has distributorless ignition with full ECU control of spark advance, instead of a distributor with solenoids crudely adjusting the vacuum advance. The aux port systems are the same between the two essentially. The s4 BAC valve is much more advanced than the s3, as the s3 is just an orifice controlled by two vacuum solenoids while the s4 is actually duty controlled. The throttlebodies are very similar in function. The manifolds are similar in function but they look and fit differently.

The s3 has the coolant seals located on the rotor housings. That's one of the biggest differences. The s3 also has heavier rotors and 3mm 2 piece apex seals, versus the 2mm 3 piece seals of the s4 (Mazda has gone back and forth between 2 and 3 piece apex seals over the past few years). The s4 n/a motor is way more advanced than the s3.

 

Thanks thats what i needed, i was going to try and use s4 t2 manifolds and boost it, looks like that wont work.