No, i may have said that in a way that could be easily be misunderstood. The "13" in 13b means the displacement of 1300 cc. I really meant the engine *changes* between S4 and S5 turbo II are small.

About 15 HP gain, both turbo and N/A. Technology got better, so did the cars electronics.

thanks for all the posts.

if you all want to leave me with more info about then i would love it.

I believe the S5 rotors were lighter, which is part of the reason for more power over the S4. I've also read that the S5's were slightly heavier (the whole car, not just the engine).

S4 NA = 146 bhp

S4 T2 = 182 bhp

S5 NA = 160 bhp

S5 T2 = 200 bhp



Those are the stock ratings from Mazda. Higher compression, lighter rotors and a different intake manifold design along with a different auxillary 5/6 port actuation are the main reasons for the NA power increase. The T2's I believe had a different compression ratio too and a bit more boost for the power increase.



Like Phins said, some electrical changes in engine from S4 to S5 were from mechanical to electric oil metering pump (this is what lubricates the inside of our engines), different throttle position sensor (I think dual position instead of the single plunger TPS from S4) and mass air flow sensor went from the flapper door type to whatever the S5 is... I cant remember anything else.

The S5 intake plenum was also improved with VDI (Variable Dynamic Intake, I think it is).



S5 TII compression ratio 9.0



S4 TII compression ratio 8.5



S5 6pi (6 port-N/A) compression ratio 9.7



S4 6pi (6 port-N/A) compression ratio 9.4

im trying to figure out why rx7kid reported this thread?

reported it? WTF? he sounded pretty damn pleased with the help he was getting

i think he got confused and reported it

no your just a bastid rob lol. this poor guy sounds confused. The ECU in jeff's (DJ Blu) 88 T2 is about 2 times the size of mine. The turbo in the S4/S5 cars are different, the injectors, the pulse dampener (no more fire), the wastegate is slightly larger (.5mm i believe) and works better.