theboy

as i know our car has the same engine, the only different is the gear box, how come only 6 speed has 250HP?

question 1. can we modify to get 6 speed power? even 4AT?

question 2. what is the different in the spec?

ZOOMNRX8

Every car will loose power through the driveline. Auto cars loose more power because of the torque converter. In our case the A LOT. You should search this.. I don't know the nitty gritty but since the rx8 isn't full of torque the auto transmission suffers and you loose 40 HP. Think of it of around 15% power lost in Manual Trans cars and 20% lost in Auto Cars.

DreRX8

Not to mention that the 4at and 6spd DO NOT have the same engine. The 4at is a 4-Port while the 6spd is a 6-port-so not only do you have the driveline loss to deal with the 4-port looses most of its power from the top end. As the power curves are similar up until the higher revs. Now the new 6speed A/Ts use the 6-port engine with a lower redline, this is because Mazda doesn't have a gearbox in its inventory that can handle 9000 rpm yet. The real achilles heel to the 4at is not really the power loss but the gearing of the 4 speed tranny. Even with 197 flywheel HP the 4at would not be so bad off the line if it had a better gearbox. Supposedly the new At's are about second to a second and a half faster.

In terms of getting more power for your 4-port--well you could get exhaust and intake combo and maybe pick up 5 to 10 extra horsepower. But to really make your 4at faster than the 6speed you'd need nitrous or turbo/super charger. Even still the tranny doesn't make the most efficient use of the added 50-60+ horsepower; and if you decide to go that route you'd need larger injectors, a tranny cooler (not a bad move to get one anyway), and a second oil cooler would be nice. The tranny should be able to handle the extra 50 or so horsepower without an issue considering its a descendant of the gearbox that was available with the FD.

dmp

....not to mention (but I am) the 6sp MT does NOT have 250hp....try 220hp for the 6sp, (238-ISH, right?).

guy321

It is LOSE power, not LOOSE power.

starsky1231

"It is LOSE power, not LOOSE power."

If you are spinning your wheels, then it is loose power.

khtm

Dre, I thought the new Autos had the 6-port engine?

18bsTiRX8

Yes, 6-port.....and the reason the A/T has less power is because the redline was dropped from 9k to like 7k or so (I don't drive the A/T so I don't know for sure). Theoretically, same torque because the torque peak is still in the A/T range, but since HP is a function of torque that relies on RPM, the HP numbers drop.

The reason the rev limit must be dropped is because the torque converter (better described as a fluid coupler in a modern trans) can not handle 9k rpms. You need mechanical coupling (ie clutch). And this isn't a prob with Mazda development, more so physics. Short of some exotic somewhere that may have accomplished this (and I have no idea why they would even try), no manufacturer that I know of has ever produced a production A/T that can handle those kind of RPMs.

In short, the benefit of the 8 is it's high rev limit so to take advantage of that, learn to drive stick

zoom44

not to mentionb he is in malaysia which means he has a parralel import and so he has japanese spec cars which are rated at 250ps and 210ps there. which is what he posted THE RATED instead of whatever anyone whats to argue about. stay on target

zoom44

it does thats why he said it

khtm

All I read was

Rich Rx-8

I say get an exhaust and a cold air intake, then engine swap the new 6port and transmission into the 4port, then later down the road maybe get an upgraded trans and a supercharger or nitrous.

Rich Rx-8

Yeah me too.

Ericok

Not to mention the AT has a redline of 7,500 (because the torque converter can't take more) while the MT has a 9,000 redline.

DreRX8

Car and Driver did a test of the 6spd A/T in the new MX5 and they said that it was pretty good and that it didn't trade off too much to the manual in terms of acceleration. Thats the same gearbox as in the RX8, IIRC, so the new 6spd auto may be a nice trade off for those that don't want a manual now--plus all the aftermarket parts that work on the M/T will almost definately work on the new A/T. I have a 4at and I'm satisfied with it, but my next car will be either a manual or SMG style. I plan on keeping this one as a second vehicle and seeing how far I can go with its performance i.e. boost. Until then its serving its purpose.

sosonic

Some other info:

1. The 4AT redline can be increased to 8,500 to 9,000 via ECU flash (8,500 is safer unless you have customized torque converter and/or at least Automatic transmission fluid cooler).

2. Automatic Transmission Fluid Cooler and new Automatic Transmission Fluid is highly recommended if you do this.

3. Cold Air Intake( AEM, Mazdaspeed, or RB seem good), Pulley (so far Agency or Unorthodox), Exhaust (lightest, most horsepower... don't know yet), and 2nd oil cooler (for 4AT and various 5 speed manuals) will defintely help.

4. Customized Torque Converter.

The present AT torque converter prevents you from launching past 2,500 RPM, which hurts 0-60 times. With a customized one, which do exist ( there are customized torque converters made for other cars) and we ( AT people ) are waiting for someone to make them for the RX-8. Re-amemiya has a project to make them (which will not be finished in spring 07), hopefully somebody else will too.

With a customized torque converter the ATs would be a much closer match to the M/Ts. They would be able to launch in the 4,000 to 6,000 range and there should be a pickup in HP numbers too.

The Ace

All except (4) will do diddly squat. The increase of redline will produce more noise, worse mpg, increased probability of engine failure and nothing else (powerband takes a HUGE plunge after 6500rpm). ATF is for.....what ? Maintainance ? CAI and exhaust will yield *some* HP gains, but not much.

(4) is the most effective, but not such a big deal. The 4port 4AT is just the VERY slow dog of the RX8 family....