I was looking at rx8's and wanted to know why one of the automatic rx8's only come with 197 hp and all the other models come with 237hp? Can somebody help me out?

Automatic has 4 intake ports, Manual has 6. This means the manual can breathe up to 9000rpm, while the auto cannot. The cars make relatively the same power up to the auto's redline (with the auto making slightly more due to intake tuning). The reason for the engine differences is that Mazda didn't put up the cash to develop an automatic transmission for the car. They used the parts bin. Resulting in a torque converter that cannot rotate at 9000rpm (well it would rotate but wouldn't transfer power very well and probably not for long :) ). So it got the lower reving engine.


Edit: to be fair, building a torque converter that had a reasonable stall speed and could reliably handle 9000rpm would be expensive, but I think people would have paid for it.

Supposedly for '06 the auto is rated at 212Hp seeing as its using the same engine as the 6speed.

^but still rev-limited to 7500rpm

SMG is the way to go to get the fully-unleashed 6-port automatic :D:

SMG /= automatic :)

Smg ?

sequential manual gearbox, what the BMW M3's have as an option...

So is the auto still capable of getting power out of aftermarket parts as much as the mannual versions?

most of the aftermarket parts available bolt on to both auto and manual version RX-8's, so i guess yeah....

Does anybody here have the automatic version ?

yup, there are quiet a few of AT owners on the board (i'm not one of them).

there is a section devoted soley to AT peformance mods here.
http://www.rx8club.com/forumdisplay.php?f=97

Does anybody here have the automatic version ?

I do. It's a compromise, but that's what the 8 is all about. It's slow off the line, but moves along just fine in the power band. It'll blast through the twisties with confidence, no compromise there. With the new 6spd auto it'll be even better, though still slow off the line.

sequential manual gearbox, what the BMW M3's have as an option...

It's actually Sequential M Gearbox, but everyone changes that M to mean Manual...

It's actually Sequential M Gearbox, but everyone changes that M to mean Manual...

So what does the M mean?

uh,manual.I suppose........

The same thing it stands for on the M cars, Motorsport.

It's actually Sequential M Gearbox, but everyone changes that M to mean Manual...Nope, it does stand for "Manual", not M. Although it originated on the M3 and found its way to other M cars, SMG is also available now on many normal BMW's like the 3 and 5 series.

From BMW's website http://www.bmwusa.com/vehicles/M/M3Coupe

Power. Precision. Passion. Together they define the essence of the M3 Coupe. Its 3.2-liter, six-cylinder engine produces 333 horsepower, enough to launch from 0 to 60 mph in a staggering 4.8 seconds*. Its six-speed manual transmission or optional Sequential Manual Gearbox (SMG) and road-gripping M Variable Differential lock make any trip a soul-stirring experience.

oh boy

Nope, it does stand for "Manual", not M. Although it originated on the M3 and found its way to other M cars, SMG is also available now on many normal BMW's like the 3 and 5 series.

From BMW's website http://www.bmwusa.com/vehicles/M/M3Coupe

Power. Precision. Passion. Together they define the essence of the M3 Coupe. Its 3.2-liter, six-cylinder engine produces 333 horsepower, enough to launch from 0 to 60 mph in a staggering 4.8 seconds*. Its six-speed manual transmission or optional Sequential Manual Gearbox (SMG) and road-gripping M Variable Differential lock make any trip a soul-stirring experience.

That's fine, but SMG is registered to BMW and it stands for Sequential M Gearbox. All your link shows is that BMW's sequential manual gearbox is called SMG.


Now lets get back on topic :)

That's fine, but SMG is registered to BMW and it stands for Sequential M Gearbox. All your link shows is that BMW's sequential manual gearbox is called SMG.


Now lets get back on topic :)

You just got
:spank:

Cos the sort of people who drive autos do not need the extra power, they are happy to pooter around in a lazy sort of way. ;)

and ther are lots of Sequential Manual Gearboxes that have clutches. What peopel mean whent hey use the BMWterm SMG is a manual that operates the clutch itself instead of the driver

I am still disappointed that after all of this time, Mazda still couldn't put together (or find) an automatic transmission for the 2006 RX-8s that could match the 9000 RPM redline of the manual. They should have just trashed the automatic transmission and gone for SMG for 2006.

I mean even though the 2006 ATs are going to have the same engine as the MTs, they're still getting the short end of the stick since the transmission is preventing them from making the full power that the 6 port is capable of. It's great that the automatic will have more power next year, but it's still making less power than it should be.

Good thing I swapped to stick this year. :buttslay:

^but still rev-limited to 7500rpm

SMG is the way to go to get the fully-unleashed 6-port automatic :D:

Too bad the SMG is only available from BMW. The manu-matic gearbox in the Auto RX-8 is a full-on automatic transmission that has the ability to trigger shifts manually - but it's no "sequential manual gearbox"

other companies do offer clutchless(meaning clutch operated by the tranny) manuals.

There is a very simple reason Mazda hasn't gone to the "SMG" type transmission - cost. I would expect it to add at least $4-5 k to the price. Check out the costs on BMWs! I don't think many auto enthusiasts would spring for that! Most of those who opt for an auto don't want to be bothered with shifting, and the main reason for the "SMG" type design is its' shifting prowess.

Further, I don't think the lack of the "SMG" style transmission has much to do with patents, as the prototype/concept car for the RX-8 had one! Unless they added a BMW trans to the concept car. The concept car shift lever had reverse, drive (auto shifting), and manual shift positions, with the shifting done by paddles on the steering wheel (used in production with the automatic).

Anyway, the reason the HP in the auto is lower is the rev. limit imposed by current torque converter designs - 7500 RPM. The higher HP generated by the "high power" engine design (the six intake port used on the US manual models), occures above 7500 RPM. Mazda reasoned there was no point in using that engine when they couldn't utilize its' power increase, so they also developed a less expensive to produce four intake port "low power" engine for the auto. That four port engine is also available with a manual gear box (both 5 and 6 speed are offered) for a lower cost option in some countries. Also note that what each country gets is decided by that countrys Mazda distributor/importer. In the US and Canada, that is Mazda North America Operations.

6speed manual isn't offered for the 4-port in other markets--only 5 speed. An SMG option wouldn't add that much--look at the Toyota SMT in the MR2. It could be done, but it needs development time as I don't believe there is a sequential gearbox already in use in the Ford line up--do they even use one in any Europe only cars? Even Aston Martins use paddle shifted autos--no sequentials, yet (?) at least.

Bah paint cost $$$ on BMWs, Mazda already has a sequential manual gearbox, albeit one for itty bitty commuter cars. The transmissions aren't that much more complicated than the AT or MT. I'm sure Aisin makes one or three, it's not like Mazda develops their own transmissions.

SMG type gearboxes can add weight, quite a bit of it, with all the hydraulics and such. The SMG wouldnt really appeal to people who want autos, just to people who want a manual, but would also go for the faster and always 'perfect' shifts the SMG offers. The changes and start/stop are still far less smooth than a regular auto-tranny.

Also in Ike's defense, I always heard of SMG as Sequential M (M for Motorsports) Gearbox. The SMG is a sequential manual gearbox, but thats not what it stands for.

As much as I hate to--I have to back Ike up on this too. BMW happened to coin their units with the same letters of which it is.

Anyway, the reason the HP in the auto is lower is the rev. limit imposed by current torque converter designs - 7500 RPM. The higher HP generated by the "high power" engine design (the six intake port used on the US manual models), occures above 7500 RPM. Mazda reasoned there was no point in using that engine when they couldn't utilize its' power increase, so they also developed a less expensive to produce four intake port "low power" engine for the auto.

Uh...HELLO. :xyxwave:

The 2006 automatics are going to be mated to the 6 port engine...not the 4 port. Surely you've stumbled upon one of the two hundred 2006 RX8 threads on here and discovered this.

So everyone is now dumber for having read what you just wrote. :pat:

SMG type gearboxes can add weight, quite a bit of it, with all the hydraulics and such. The SMG wouldnt really appeal to people who want autos, just to people who want a manual, but would also go for the faster and always 'perfect' shifts the SMG offers. The changes and start/stop are still far less smooth than a regular auto-tranny.

Also in Ike's defense, I always heard of SMG as Sequential M (M for Motorsports) Gearbox. The SMG is a sequential manual gearbox, but thats not what it stands for.

Brilliant thinking on their part, just like Kleenex naming their Kleenex Kleenex ;) :rofl:

Uh...HELLO. :xyxwave:

The 2006 automatics are going to be mated to the 6 port engine...not the 4 port. Surely you've stumbled upon one of the two hundred 2006 RX8 threads on here and discovered this.

So everyone is now dumber for having read what you just wrote. :pat:

but they are still limited to 7500 rpm. hows it feel to live up to your user name
:spank:

I guess you all must have skipped over the the post I made on this thread where I already mentioned that fact:

I am still disappointed that after all of this time, Mazda still couldn't put together (or find) an automatic transmission for the 2006 RX-8s that could match the 9000 RPM redline of the manual. They should have just trashed the automatic transmission and gone for SMG for 2006.

I mean even though the 2006 ATs are going to have the same engine as the MTs, they're still getting the short end of the stick since the transmission is preventing them from making the full power that the 6 port is capable of. It's great that the automatic will have more power next year, but it's still making less power than it should be.

Good thing I swapped to stick this year. :buttslay:

So what exactly were you getting at with your comments then please?

The cars the original question was on are configured as I discussed. The 06 auto will have more power, but will still be lower than the manual - I suspect it has a rev. limiter programmed into it. I also suspect the auto six port engine intake tract is configured to enhance torque at lower RPMs, as they don't have to worry about this change dropping peak HP, as they aren't going up to that RPM (you can usually optimize the intake tract for low end torque or high end HP, but not both). The manual engine intake tract configuration sacrifices a bit of HP (torque) in the 6000-7500 RPM area for better flow above 7000 RPM.

In other words, the 06 auto engine is still "different" than the manual engine. It is still a lower power engine, it's just "better" than the previous one.

I also suspect the auto six port engine intake tract is configured to enhance torque at lower RPMs, as they don't have to worry about this change dropping peak HP, as they aren't going up to that RPM (you can usually optimize the intake tract for low end torque or high end HP, but not both). The manual engine intake tract configuration sacrifices a bit of HP (torque) in the 6000-7500 RPM area for better flow above 7000 RPM.

In other words, the 06 auto engine is still "different" than the manual engine. It is still a lower power engine, it's just "better" than the previous one.


from looking at the intake in person at 7stock(there is a pic of it here soemwhere) and then looking at the one in my car they appear to be the same. the stated T figure is also 159 same as the manual

Besides, the question was why 197...? So Rx-8friend posted correct information. Though it had been posted earlier in the thread.

Edit: Now that I've thought about it a bit, the 6port auto probably doesn't need a intake tuned for the lower redline, because the 6port isn't going to make any more power down there due to the internals. It's already tuned for optimum low end operation (given it's port configuration) using S-DAIS.