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Series I AT-Specific Performance Mods Discuss engine and transmission modifications for your AT equipped RX-8

Rev Limit on Auto

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Old Jan 13, 2007 | 12:27 AM
  #51  
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Originally Posted by therm8
Not really.

The stall speed of a converter determines what rpm the car will take off at (when you floor it from a stop). If the car does not have enough power, you'll not reach stall speed without brake boosting. There are actually 2 stall speeds, but I'd rather refer you here: http://auto.howstuffworks.com/torque-converter.htm ; than mangle the explanation.

I'm not 100% sure what the stall on the 8's converter is, but by all accounts the tranny is from the FD, so makes me wonder if the FD's converter is the same as ours. In which case, upgrades should be easy to find.

Edit: turns out HSW doesn't really explain stall speed, but I can't remember where I saw a good explanation.


Looks like a whole lot of fricton/heat in an auto trans.
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Old Jan 19, 2009 | 09:15 PM
  #52  
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Is there, in the aftermarket, a torque convertor that can stand 10K RPM (to give a safety margin over the rev limit of the 6MT), such that the rev limit on the 6AT could be raised to match that of the 6MT without turning the torque convertor into an anti-personnel mine?
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Old Jan 19, 2009 | 09:16 PM
  #53  
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Originally Posted by longpath
Is there, in the aftermarket, a torque convertor that can stand 10K RPM (to give a safety margin over the rev limit of the 6MT), such that the rev limit on the 6AT could be raised to match that of the 6MT without turning the torque convertor into an anti-personnel mine?
No but you can get one custom built.

http://www.levelten.com/index.html

One or two here have done it.
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Old Jan 27, 2009 | 01:08 PM
  #54  
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Does anyone know if there are any dual clutch transmission swaps available for the 4AT yet, similar to BMW's SMG, which would fit in directly without tons of fabrication and interior reconstructing? It would be a great option compared to a torque converter.
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Old Jan 27, 2009 | 11:21 PM
  #55  
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do the 4 port AT 2004 rx8s have a different engine than the manuals? are they really that slow? with a small yet damaging neutral drop from 3k rpm i hit about 7 seconds in my 0-60. breaklaunch i get in the 9s. and normal you will get 11.
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Old Jan 28, 2009 | 08:47 AM
  #56  
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Originally Posted by Rx8 Fanatic
Does anyone know if there are any dual clutch transmission swaps available for the 4AT yet, similar to BMW's SMG, which would fit in directly without tons of fabrication and interior reconstructing? It would be a great option compared to a torque converter.
Not yet. Our greatest challenge is the disabling of the TCM. So far the AP is not config'd to mask the error codes that the TCM throws if the Transmission is not present. Same issue will happen if the TCM is removed, the PCM will not be happy and not allow the car to function right.

Originally Posted by em1turbo
do the 4 port AT 2004 rx8s have a different engine than the manuals? are they really that slow? with a small yet damaging neutral drop from 3k rpm i hit about 7 seconds in my 0-60. breaklaunch i get in the 9s. and normal you will get 11.
All of the manuals are 6 ports and have the ability to cluth dump at any given rpm.
We auto's that have 4 ports have a higher drive train loss because of the TQ fluid coupling. A low torque vheicle mated to a "high" loss drivetrain will give high trap times.

Last edited by 09Factor; Jan 28, 2009 at 02:44 PM.
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Old Jan 28, 2009 | 09:11 AM
  #57  
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The Accessport is capable of raising the redline. But it will do nothig for the speed limiter. Shut down at 125 mph. At least the 05's.
I know there is someone on this forum that has no limiter on their 04 AT. They have been to 153 mph
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Old Jan 28, 2009 | 10:40 AM
  #58  
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Originally Posted by em1turbo
do the 4 port AT 2004 rx8s have a different engine than the manuals? are they really that slow? with a small yet damaging neutral drop from 3k rpm i hit about 7 seconds in my 0-60. breaklaunch i get in the 9s. and normal you will get 11.
My understanding is that the 4 port AT engine is basically the same as the Euro 4 port MT engine (which has a 5 speed transmission instead of the 6 speed that the 6 port engine). The port timing is completely different from the 4 port to the 6 port engines. On the bright side, the peak torque is higher on 4 port engines, which could be advantageous in a turbocharged, centrifugal supercharged, or axial-flow supercharged setup where those compressor types need some revs to start moving air in any significant way.

The 6 port engines have a lower peak torque but a broader power band and continue to make power well past the rev limit of the 4 port engines.
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Old Jan 28, 2009 | 12:02 PM
  #59  
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Originally Posted by longpath
On the bright side, the peak torque is higher on 4 port engines....
people need to stop quoting this
you're talking "official" numbers of 164ft/lb(auto) vs 159ft/lb(manual).... hardly a difference
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Old Jan 28, 2009 | 02:49 PM
  #60  
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Originally Posted by Easy_E1
I know there is someone on this forum that has no limiter on their 04 AT. They have been to 153 mph
Any idea who, or has the name been changed to protect the "innocent"?

Originally Posted by longpath
On the bright side, the peak torque is higher on 4 port engines, which could be advantageous in a turbocharged....
I have seen more tq on a Fi'd auto (4port) running the same turbo at the same psi. but that is for another thread.

Originally Posted by cjkim
people need to stop quoting this
you're talking "official" numbers of 164ft/lb(auto) vs 159ft/lb(manual).... hardly a difference
I'm with you on this one.
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Old Jan 29, 2009 | 12:39 AM
  #61  
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yea actually a 4 port auto with a turbo doesn't gain much hp. but the torque flies way up.
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Old Jan 29, 2009 | 12:51 AM
  #62  
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and I hit 132 with my 4 port auto.. actually 135. then limiter kicked in. Will never try again...
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Old Jan 29, 2009 | 12:05 PM
  #63  
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Originally Posted by em1turbo
yea actually a 4 port auto with a turbo doesn't gain much hp. but the torque flies way up.
define "much"

40 to 50 extra whp is pretty big considering most bolt on's do crap...
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Old Jan 29, 2009 | 01:55 PM
  #64  
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^^^ nice ***. Just had to say it.

back to topic. 5psi added 100 ft lbs of tq and bout 50 hp.
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Old Jan 29, 2009 | 02:02 PM
  #65  
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^you should've seen ALL the pic's

wow, 100lbs of torque!? mother fcker must snap at the line...
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Old Feb 2, 2009 | 06:02 PM
  #66  
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I have a stock JDM 4 port and it shifts at 8300 all the time
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Old Feb 4, 2009 | 12:35 AM
  #67  
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Originally Posted by 09Factor
We auto's that have 4 ports have a higher drive train loss because of the TQ fluid coupling. A low torque vheicle mated to a "high" loss drivetrain will give high trap times.
Just to be clear, as I understand it the fluid coupling only exists in the time between shifts (1 second usually, sometimes 2 seconds @ 8000k RPM ) and when you're not moving in Drive or Reverse.

The rest of the time, even while accelerating, the engine and wheels are locked together. The "slushbox" is only slushy between shifts. That is why there's a lockup clutch when the input and output shafts are moving at the same speeds.
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Old Feb 4, 2009 | 07:37 AM
  #68  
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Quote:
Originally Posted by Easy_E1
I know there is someone on this forum that has no limiter on their 04 AT. They have been to 153 mph

Any idea who, or has the name been changed to protect the "innocent"?

Innocent? Never thought of myself that way. Do not try an emulate this as the car becomes (is) airborne and the slightest breath of air will cause real problems.
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Old Feb 4, 2009 | 12:43 PM
  #69  
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Haha nice Phil,
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Old Mar 28, 2010 | 12:02 AM
  #70  
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I've gone 154mph @ 7000rpm with room to play, it wants to go faster. Although I have a 6spd auto... Any new updates?
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Old Mar 28, 2010 | 01:52 AM
  #71  
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Originally Posted by truplayax14
I've gone 154mph @ 7000rpm with room to play, it wants to go faster. Although I have a 6spd auto... Any new updates?
I call bs.
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Old Mar 28, 2010 | 11:45 AM
  #72  
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i have an 04 auto and im looking to make my car feel faster..i sometimes feel like it is slow than other times i feel it takes off pretty good.

eventually im trying to have intake,exhaust, and tune.

will these make any big difference?
doesnt have to be a big difference but will i notice it?

whats the fastest an 04 auto could go if i got the tune to remove my govern?
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Old Mar 28, 2010 | 06:06 PM
  #73  
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Originally Posted by RotaryP7
I call bs.
No bs, was going down I-95 at 3am. My friend and I were driving to top out his ss, I was trying to keep up.
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Old May 28, 2011 | 12:42 AM
  #74  
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I have a question about a 2010 a/t , how could you raise the rev limiter on the car , and till when would it be safe to raise it with the stock torque converter?

Also can you play with the timing of a rotary like you can with a reciprocal engine to advance the torque curve ?

and if so why the hell did mazda not do that from factory to the A/t or did they ?
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Old May 28, 2011 | 08:57 AM
  #75  
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Originally Posted by Tem
I have a question about a 2010 a/t , how could you raise the rev limiter on the car , and till when would it be safe to raise it with the stock torque converter?

Also can you play with the timing of a rotary like you can with a reciprocal engine to advance the torque curve ?

and if so why the hell did mazda not do that from factory to the A/t or did they ?
You can get a Cobb AccessPort from MazdaManiac to cut the rev limiter, I believe some people have reported sluggish shifting when over 9K though.

Rotary engines don't have timing belts but you can manage some things through the Cobb AP.

The intake and exhaust are about tuned to the max from the factory while still being emissions legal, and no turbo, there is just not a lot of power at low rpm's in a rotary engine.
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