automatic vs. manuel redline
 

i have a question about the lower redline of the auto rx8s. is the redline difference because of the different motor? i read that the six speeds had a six port and the auto had a four port engine. or is it because of something else in the drivetrain? would there be any performance gains in raising the rev limiter on an auto and if so how would i go about doing so? any help or info you can give me would be very appreciated.

the 04 -05 4spd ATs have 4 port motors - the 6 spd AT has a 6 port .

See the AT forum for "interceptor" and you will find your answers

the lower redline stems from the torque converter. it cant handle the higher revs. you could go custom for a better converter

also the 04-05s had a 4 port motor.

what about 07s? I would really like to mod my car to be as fast as the manuals

well sorry to say you need to just trade your car back in for a manual then. The money you'd spend trying to catch up to a stock RX8 - is wayyy more then the loss you'd take on just trading in.

Not really.. the only thing a manual has on the autos (6 spd anyway..) is like 1500 - 2000 more rpm's on the tach. Other than that, the autos are making more power to the redline.

From what I understand, torque converters are the very last thing you add if you are going to mod your car, you have to get all your other stuff in before it like the forced induction system and whatnot.

I am curious though to see what is affected by the redline.. like overall what do you have to reinforce and upgrade to be able to take a higher redline on both models? I'd love to see an Rx-8 with a double digit redline that will run longer than an hour..

the difference is not JUST the 2 k more RL........

Off the top of my head, redline in piston engines is controlled by 3 things: Quality of the balance, max speed of the piston, and value train. On a lot of engines, the valve train winds up being the limiting factor. The value springs are unable to return the valves fast enough and you get valve float, broken stems, bad things. There can also be choke velocity in the intake, but that is easier to work around. Now, in a rotary, you have no valve train so that limit is removed. I'm pretty sure the design of the engine does not approach any kind of rotor tip speed maximum, but that may exist. Balance of the engine can be a factor. I think, mostly, the geometry of the intake/exhaust and the tune gave the 6-port manual a power curve and it peaked before 9k. There was no need, then, to go to 10k. A manual transmission, being mechanical links, handles the high speed motor output shaft fairly easily. The automatic transmission has to work with the limitations of the fluid mechanics that exist in the torque converter. Being the only rotary car on the market currently and probably possessing the highest redline of any reasonably price automatic (does an S2k come with a 9k auto redline?), the impetus to design a higher performance torque converter is probably not very high. The auto, then, is retuned for a lower redline and produces more torque. This leads to higher power at the listed RPMs. The power that makes its way to the wheels, however, is significantly less. When the auto peaks and hits redline, the manual continues to make and increase in power. It is fairly tough to argue that the 4 port engine is actually faster or stronger than the 6 port in stock trim. It is, however, tuned for better torque in the RPM range it does use.

I'm not familiar with the strength of the auto Mazda is using in the RX-8, either in the 5 spd or 6 spd, but autos traditionally suffer when subjected to higher than stock power levels. They develop more heat and can be overworked faster than the manuals. Then again, if you drive a manual poorly, you can destroy a trans pretty quick at stock power. Traditional auto trans mods include secondary filters for increased debris removal, trans oil coolers to help dissapate the increased heat, shift kits, and high stall/performance torque converters. The nice thing about autos in the performance environment is the shift speed and shift consistency are tough to match. In handicap bracket racing, autos fair well.

In closing, paddle shifters are pretty cool!

It's on the intarweb
 

The AT6 is putting 212hp@7500rpm vs 232hp@8500rpm for the MT6 (source is Mazda Canada website). AT is not "making more power to the redline" whatever that means. :scratchhe

I think what he is saying is the AT6 makes 212hp@7500 rpm and the MT makes less than 212 @7500 RPM which I think is true. You could counter by saying the MT is making 232@8500 and the AT6 is making strange noises at 8500.

The major limiting factor of the auto is the torque converter, at those revolutions you would start seeing cavitations like in a boat, and thus ruin the fluid inside.

i believe the torque converter is the same one from the FD rx7

the 07's are 6speed 4 ports. 06 was the only year that had a 6speed 6 port for the ATs (so far at least).

im fairly sure the 07s are 6 port...

you'd think a change like that would be mentioned in the spec deck

https://www.rx8club.com/attachment.p...chmentid=81933


or that they would note that difference on the website like they did in 2004 and 2005

http://www.mazdausa.com/MusaWeb/disp...ehicleCode=RX8


or that maybe i would have made mention of that before if it were true.

The best thing about the 6port ATs is that if you raise the rev limiter the engine breathes very well (due to the extra intake ports), so you'll see a pretty good gain in power. 8000rpm shouldn't be too hard on the TC, if it cavitates there, it's likely cavitating at 7500rpm as well. You'll only see 8k for the briefest of moments anyhow. The biggest problem is slip. At 8krpm the converter may have excessive slip, efficiency goes way down, and the extra power made at the engine is used to simply heat up the ATF. Torque converters operate much like a centrifugal pump, and thus have optimum ranges of efficient operation. My guess is that most of the extra power would get to the wheels. But don't ever expect to be as fast (straight line) as a MT. Even if you had the same redline and power curve, the 6MT is geared much more aggressive than either the 4 or 6AT. The only way to top a non-FI'd MT is a little FI for yourself.

No one has confirmed that the converter (4AT) is the same that the FD used, but since the 4AT transmission came from the FD (modified for electronics) one might assume that the converter tagged along. Level10 modifies FD converters for higher stall and better efficiency, so that'd be a good way to find out. Mine's a daily driver, and a new converter costs over a grand, so sending it off isn't an option as of right now.

Zoom, no need to be snotty.

If you go to http://www.mazdausa.com/MusaWeb/conf...modelYear=2007 and select the 6spd auto, you will notice that the description changes from 6port to 4port, regardless of the trim level. So it may be true that 07's have 6 port, but perhaps someone should tell Mazda that.

Well, Ya had me going. So after a quik call to the tech dept. the 07 6spd autos are indeed a 6 port engine.

so basically we gotta change the torque converter to be as fast as the MT?

I think people are mixing things up.

The torque converter issue is with how high you could rev the engine from a stop. The Auto torque converter prevents you from going past 2,500 rpm at rest. A manual could rev to 7,500 rpm and take off (of course clutch life would be very limited). A custom torque converter would allow the Auto to "brake launch" from say 4,000 rpm or a bit better.

Autos could also do a "neutral slam" at something crazy like 7,500 rpm, but expect your auto transmission life to be very limited. But in theory, an Auto could launch at the same rpm as a manual if you don't mind buying a new transmission soon or if you have taken special care of the Auto transmission (via cooler and good AT fluid) or maybe a customized torque converter.

How high you can rev while in motion, I thought was about heat. The auto needs a good tranny cooler to keep the heat down while at high revs above 7,000 rpm. Mazda went cheap on the auto and did not provide a good tranny cooler. You also need good AT fluid like Redline or Royal Purple. I bought these and have regularly gone over 8,000 rpms in my 4 speed Auto with ZERO problems. The problem though is launching at high revs (0-60 and 1/4 mile), but keeping the auto a good daily driver. Top speed though, 150 mph, is not a problem if your tires can take it and you remove the rev-limit via ECU flash.

^ oh about that, sorry to be out of topic here but.........can a piggyback ecu remove the damn limiters also?

meh- im always snotty about stuff like that. here i am trying to get the facts out ot everyone by geting ahold of speck decks and price lists and order forms etc etc and then people come along and contradict that work. i get a little snotty about it. nothing personal. i have alerted them to fix that error on the website

On the 05 MT how many ports are there? 4 or 6? thanks

The 6MT always had the 6 port engine.


EXILE

here one thread where we talked about it a little, no one has really gotten one and documented it so...

https://www.rx8club.com/series-i-specific-performance-mods-97/pros-cons-customized-torque-converter-100956/

Thanks I thought so but wasn't sure.

Hmm.. Charles you brought up a damn good point that I think no one has thought of.. why who the hell knows.. the PC for the tranny... would be easier to alter that one would imagine than having a custom converter built and installed. Hopefully Mazda was kind to us and made it simple as sin. I just wish they made 4th gear (in the 04-05 models) actualy useable instead of a useless cruising gear. That and a related question.

Would our speedlimiter be contained within the tranny PC instead of the ECU. We are limited to 124 (or so I'm told hehe...) so if we Auto owners could get rid of that limited omfg I'd be happy!! :rock:

It is 124....before I had the mt I drove a 05 at....and even going down hill I couldn't get the car past 124....would make power up to it...but then wouldn't go any faster...or was it 115 I am thinking about.....either way it was limited

its not 115...... :)

I wanna find the engineer that came up with this wild idea of making our cars ECU so damn fuquing hard to crack and drag him out into the street and shoot him. Mind you this will be after he hands me the magic key code to unlock it all lol.. I dont understand Mazda's application of the speedlimiter on the Auto's when the MT's dont have 'em. And no I aint gonna buy the "cause its a A/T thats why it should be limited" bullshyt responce either since to me its a cop'out. I heard that Moon at Pettit was looking into eliminating or atleast fooling the ecu via Int-X or another program 'cause he himself owns a Auto and has the Pettit S/C on his car and is sick of the 124 speed limit while hearing of MT's doing 150+

I'm with you on this one. If we were to ever meet this guy(s), I'm sure we would find out he/they were lacking in common sense. I'm sure the guy(s) have the book smarts and brain power to burst light bulbs from across the room, but lack the common sense of the average Jiffy Lube mechanic.

Making the ECU easy to program and to have easy tools to re-program the ECU, just helps Mazda overall and helps all the people driving Mazdas.

Custom torque converter or Auto tranny PCM flash...

Charles brought up some really good points.

Re-amemiya had a project to create a custom torque converter for the RX-8 Auto, which should have been completed or close to completed by now. The R-Magic guys in Japan, were doing and knew about a lot of "funky" things being done to RX-7 Autos. Since the RX-8 inherited its Auto tranny from the RX-7 than there may be some good info. there. I will fish around for information from them. But, it may come down to good old American ingenuity in the end to "fix" the issue. Just like in the case of the SC and turbo for the RX-8.

These guys make trans-brakes for dragging - http://www.fbperformance.com/NewSite...nsmissionID=92

The thing is to find a solution that allows you to use your auto RX-8 as an everyday driver and launch at 3,500 rpms or above. If you could launch the RX-8 auto at 5,000 plus rpms, without smashing your auto transmission or doing a neutral slam, than that would shut up a lot of people that dog autos.

Another point too, is that the Auto RX-8s have a torque advantage over the manual that is not being realized/seen due to the stall and lower rpm launch issue.

Federal regualtions require a 125mph governor on all vehicles that don't come with tires rated for speeds higher than that. Anyone know what tires come standard on the base automatic? That's probably the reason.

Racing Beat could easily get rid of it, and boost the power a bit, but they've already decided the AT isn't worth their time...

Using the brakes, stall is around 2500rpm. Flash stall (just flooring the pedal and watching the rpm) appears to be 2200-2500ish. It has been a while since I tested any of this though, so maybe someone with more recent experience can verify. I posted it here somewhere, I'll see if I can dig it up.


Diameter I'm not sure of. The transmission is of the RE4 family that Mazda has used for years (shared with Ford I believe). The FD used it or some iteration of it. Which makes me suspect that the converter is likely the same one the FD used. The low stall speed wouldn't be as much of an issue on a car producing 250lb-ft of torque.


Level10 does some of this for the FD (2800rpm is the estimated stall after the work). If I had an extra converter laying around I'd send it in. Maybe I'll start hunting through the internet junkyards. A new OEM one is rather expensive.



Edit: all of this is for the 4AT, as I know very little about the 6AT. Really I don't know much about the 4AT either :)

After further research I should ammend my previous statement. I think it's in the RE4 family. Nissan uses it as well it appears. The RE4 gear ratios don't match the 4AT rx-8. The 4EAT's do, however, but I thought that was a old transmission. Turns out, I don't know anything :wavey:.

Here's the gear ratios for the 4AT 8, maybe it'll help people searching for info:
1st: 2.79
2nd: 1.55
3rd: 1.00
4th: 0.69

I'll keep digging, maybe something will turn up.

n charles found out that some suspension components r also made by mercedes n some parts from mitusbishi......all new cars nowadays r all put together by parts of different companies n the reason why is simple, CHEAPER on parts costs.

Well the internet sucks...information roadblock. I popped off an e-mail to Trussville Mazda, we'll see what they say.

Ok, I just went to the track, I messed up, my car limiter is also 124, the 147 was downhill, so I guess that would be why, as of currently, I am seriously fund-limited, but I do want to get rid of the damn thing, so I would like to ask you whether the e-manage piggyback can do the job or can I buy like just a limit-destroyer type product?

As in my previous post Moon over at Pettit is hoping to tinker with Emanage or was it Int-X to nix our speedlimiter. I'm unsure what the base model tires are now but I have a set of Avon Tyres Tech M550 A/S 225/55ZR16 on mine atm. Be nice though if someone can find that magic line in the code to eliminate this.

mine came with a dunlop GT racing tire.....thats for the 17" wheel I think......

and as for the speed limiter.......I been searching around and some products seem to beable to disable it....but it says for japanese cars....IDK if it will work for the rx-8

the tire ratings are in the instruction manual in the car, look in the back. my tires are stock and are rated to 149. sooooo i dont really think that the government would say that the car can only be limited to 125.

same here........149mph.......so screw da limiter.........

btw.....I was thinking of buying this

http://www.racerwheel.com/sard-62301.html

and see if it works.....thoughts?

I'll just wait till Moon at Pettit or someone else finds that magic line in the code and eliminates it (or rather block it really), soon after that I'll buy that piggyback ECU from 'em since it will be then worth it!! :rock:

I see.....I asked the seller...all they said was......"it "should" work since mazda rx-8 is a japanese car right?"

..................

im curious to know if the cars are limited because there made in japan. does anyone know if the japan cars are limited too?

Not really.
In fact, the old version of JDM speed limiter defencer does not always works for the newer car models using CAM BUS communication in ECUs.
For example, the SLD series (by HKS) for RX8 has three versions ( III-Z1 for 6 MT without immobilizer and DSC, III-Z2 for AT without immobilizer and DSC, III-Z3 for 6MT with immobilizer, 4AT with immobilizer but not DSC).

The seller surely has no idea of what he's selling.