I know a fb is a 1st gen, a fc is a 2nd gen, and a fd is 3rd gen but what does s4 or s5 stand for

 

Series 1- 79-80
Series 2- 81-83
Series 3- 84-85
Series 4- 86-88
Series 5- 89-91
Series 6- 93-95

 

which series is the better one to do a t2 swap a s4 or s5

 

Also the '79-'80 were "SA" and not "FB".

In 1981 Mazda switched to the now common-place VIN system. The early VINs were something like: SA22C-501234

There are more details in the FAQ. Search for "FB" on https://www.rx7club.com/1st-generation-specific-1979-1985-18/1st-gen-rx-7-faq-page-237777/

 

s5 i believe would be the better TII swap had a little more power if i remember correctly. good luck finding one though. People grab them pretty quick.

Fred

 

Just to fry your noodle even more, some countries (like here in Australia)... our 1st gen cars are labelled as series 1,2,3, yet still have the Sa22c vins...even though the options/factory specs on them are certainly not Sa22c!

 

Don't forget that there is the '83 and also the '83 1/2, which is basically a Series 2.5, having a random mix of series 2 and 3 parts.

 

Ok, I think we have confused him enough!

 

S4 Good........is easier to find,cheaper and mechanically easier to swap into the 1st gen since it has more in common with the GSL-SE engine.Plenty of upgrades out there to make more power,including a S5 turbo upgrade.
S4 Bad......its less HP and torque than S5 out of the box.Its control systems are more archaic and restrictive and theres no conventional check engine light.Exhaust manifold and wastegate designs blow goat ***.

S5 Good....faster ECU speed,smoother controls and AFM,more power and torque out of the box,WAY better manifold and wastegate design(same turbo compressor),no EGR valve,has a real check engine light. All in all,more refined than S4.
S5 Bad......costs more,harder to find.The electronic OMP makes 1st gen motor mounting difficult (but not impossible) to do when retaining the stock ECU and oil metering.S5 turbo wastegate bulge gets very close to the idler arm...HOT,HOT,HOT

Either can make a 1st gen quick.I ran both and was floored by the difference in pickup compared to my old carbed 12A and 13B.If you want a rotary to make torque like it never had before,the TII engine delivers.I have to give the nod to the S5 though.Its been much less quirky with its controls,its cake to diagnose and the off-boost power is better.The "bads" of the S5 swap are more than offset by the good.It wasnt too hard to overcome the S5 problems once I became familiar with the TII engines.

 

thank you for all the help guys