Just purchased an 05 rx8 AT, I was wonding besides the transmition what is the major difference in the 2 cars. Why does the 6 speed have more pony's. Sorry for the newbie question just trying to understand.

058

 

the 6 speed has 6 ports and the auto has 4 ports

 

I've heard (so please don't flame if I'm wrong) that the AT can't handle a 9K redline. Something about a torque converter? Can anyone confirm this?

 

Yup. During development of the RX-8, Mazda had neither the time nor development budget to design a new auto transmission that could handle the high rpm of the Renesis.

Since the AT imposed a rev limit of 7K on the engine to be used with the AT, Mazda took the opportunity (easy) to design a less expensive version of the engine to be used with the AT. Since the AT engine version would never rev to 9K, then it didn't need the extra intake ports in the rotor housing, the extra valved intake path in the intake manifolding, the extra (third) fuel injector per rotor, and so on that allowed the Renesis to make additional power in the 7K to 9K rev range.

You would find that the power and torque curves of the Low Power engine (fitted to cars with the AT) and the High Power engine (on 6 speed manual trans cars) are nearly identical up to 7K rpm. The Low Power engine stops there, and the High Power engine continues to climb in revs and power, making ~30 hp more because of the higher revs and better breathing at those revs.

This also means that the AT engines can never be simply modified to make the extra power back - even if someone tried swapping in the 6 port Renesis and all the extras, and somehow managed to reprogram the ECU to allow the 9K redline while controlling the AT, they'd just blow up the AT transmission.

 

yes.

beers