I'm new to the rotary engine, so this may have an obvious answer. I'm wondering about the 238 vs. 197 horsepower numbers. Could Mazda have just as easily made the AT with the same 238 HP as the manual, or is there some reason that the engines could not be configured the same?

 

They are entirely different engines. The auto version has a 4 intake ports which are smaller. The manual version has 6 intake ports. The timing stays open later for more top end, it has more intake runner area, it has shorter intake runners, it has a much higher redline, etc. It is so much more complex than just raising the redline. The manual engine just has so much more breathing capacity. The auto engine is at a huge disadvantage.

 

no the auto engine could not make 238@8500 because no auto tranny i know of could take 8500+ RPMs.

 

Near the top of the link below Gord96BRG has some comments related to your question. I recall related threads, including one that discussed using the low power engine with an MT.

https://www.rx8club.com/showthread.p...matic+AND+2005

 

Yeah, they traded HP/RPM for greater torque in the AT. The converter limits the RPM in the AT.

Ah well...neither car is a world beater...but both are snazy rides.

P.S. One thing: I won't miss or dork up a shift in the AT. Not the fastest, but I will be there when the 'race' is over.

 

There are auto transmissions that could handle the higher RPM's, albeit not in production automobiles, and not nearly small enough to fit into the RX-8. Plenty of high perfomance builders have been turning tight for years, reliably!

 

Do you really care about the HP? Remember, the AT has 5 more foot pounds of torque than the MT. This means the AT has more umph where it counts. The AT downfall is the number of gears (i.e. 4 vs 6). So, the AT has to work harder to do the same job; thus significantly defeating the torque advantage.

 

Correction, no current Mazda auto tranny could handle it.

Plus, I believe it's more the torque converter than the tranny itself, though I could be off, that just seems to come to mind for some reason.

 

As has been mentioned - Mazda's current 4 speed transmission (specifically, the torque converter) can't handle revs over 7500 rpm. Mazda could not use the high power engine that revs to 9500 rpm with that automatic, so they designed a less-expensive version of the engine (fewer ports to machine, fewer intake tract components) that didn't need to breathe at those high rpms. The torque curves are nearly identical to 7000 rpm, the extra power of the MT engine is all in the 7K to 9K range - where the auto trans can not survive.

As I mentioned in that other thread, Mazda has a 5 speed auto trans in the works that can handle the revs of the high power engine, and it should make it into the 2006 RX-8.

Regards,
Gordon