Cylestyne

Hi,

I am looking to squeeze some additional power out of my RX-8 while keeping it an autotragic.

A bit of background about my car: It is a late 04/05 Rx-8, JDM import. My country doesn't have official Mazda dealers so all these cars are unofficial imports. To my knowledge the 6AT version never came to our market, so selling the car and buying a 6AT is not an option.

I understand that in 05/06 the USDM model got bumped to a 6-port 6-AT model. What would be required to upgrade my car to the same specification? How hard is the swap? The first things which come to mind are:

- 6-port engine, this is easily available here, I suppose it is identical to the 6MT engine?
- 6-AT transmission, I would import one from the USA
- ECU? I would import one off a 6-AT in the USA along with keys etc, which would take care of the immobilizer

What else would be required? Is there a separate ECU for the transmission? If so what is it specifically called? Would the instrument cluster also need to be swapped out?

Any advice that anyone can offer would be greatly appreciated. Also, would the gain in performance be worthwhile? Please do not tell me to get a 6-MT, I do not want a manual, I've kept plenty of M/T cars and frankly I'm tired of shifting gears in our traffic.

Thank you

HomicidalApple

iTrader: (3)

So this is off topic and im not really able to help with your dilemma but just curious, what country do you live in where they dont have a Mazda dealer?

You just have really good english so it has me stumped and no location either.

Cylestyne

lol, its a small unknown country that goes by the name of Pakistan :P

mdw1000

Yeah, the transmission has its own computer called a TCU. If I remember correctly, it is mounted under the dash on the far left side of the car (at least on left-hand drive versions) of the 4AT.

RotaryResurrection

iTrader: (3)

Remember, when mazda changed the transmission from 4at to 6at, they also changed the engine from 4 port to 6 port. Now, I haven't done any work on the 6p/6at versions, or tried to do any converting one way or another on those models. It's possible you could swap only the trans and TCM (trans control module) and get it to work normally with your original 4 port engine.

It's also possible you'd have to go beyond that and change to a 6 port (automatic style) engine, PCM, wiring, keys, etc. like I had to do when I changed my car from auto 4p to manual 6p. Notice that the 6 port automatic engine/wiring/pcm is likely to be different than the 6 port manual counterparts.

Out of curiosity...if you guys have no mazda dealership, the cars were never sold in your country so used parts/junk cars are impossible to find, and imported parts are going to be extremely expensive, why would you want to own and modify a car known to have limited reliability under the best of circumstances when you live in a somewhat harsh climate? That seems to me you are just asking for trouble and high expense.

mdw1000

RR brings up another good point. I'm guessing you'll need all new wiring harnesses.

mdw1000

Definitely document the build if you decide to go through with this. I'm guessing there are other people out there that might do it if they could find the parts cheap enough. Probably cheaper in most places just to trade the car for a 6AT, but if you find a cheap donor car it might be a viable project.

Cylestyne

The mechanic I spoke to here, said the same thing (about using the 6sp on the 4port), however would there be any power gain just from the trans swap w/o 6port engine? I'm guessing it would have a faster take off due to the shorter ratios.

Yes that is a possibility I'm ready for, that is why I'm doing all the homework I can. If its possible to just make it run as a 6AT on the 4port, while gaining some power, I'm up for it.

Yes these cars are quite a risk. Our country is dominated by Honda, Toyota and Suzuki (these are the only 3 brands which have official assembling/manufacturing in our country) with other brands being official or unofficial imports. There are probably under 250 RX8s in our country.

Now as far as reliability goes, again you're right, however we happen to have a few mechanics who know how to rebuild rotaries and work on RX8s pretty well. Plus we have "junk dealers" who import engines, parts etc directly from Japan-- so getting a new engine or transmission isn't really a big deal (however I'm yet to find a 6AT from Japan).

The aftermarket support here is pretty good, you just need to know the right people. Again it is expensive. However people who can import small and non-bulky items from markets like USA are at an advantage (like ECUs and stuff which would otherwise be a bit more expensive here). Also labor in our country is quite cheap, if I was to undertake a swap like this, the most experienced mechanic that I know of who actively works on rotaries (RX8s and 3rd gen RX7s mostly) would charge me about $250 in labor for the whole deal, that includes building a wiring harness.

I'd have loved to supercharge my car but there are no experienced rotary tuners here and blowing up an engine is probably going to cost a lot more than a transmission swap. A 6port engine here costs about $2,000. This is usually a fresh import from Japan with very low mileage (10,000 - 20,000 KMs). On the other hand I've seen 6AT transmissions as low as $600 on ebay and other sites. The max it would cost to ship a transmission here would be as much as the transmission itself.

mdw1000

You wouldn't gain in power if you didn't change the engine, but you would get better acceleration to the shorter, more closely spaced gear ratios if you changed the transmission.

I have my doubts about getting a 6AT to work with the 4-port engine and ECU. I have a feeling the ECU and TCU are too closely linked.

yiksing

I say not worthwhile unless you swap it to a 6 port engine as well.

Grimm0ne

iTrader: (3)

anyword on this?

as if i get an 04, i would be doing this swap.. 6p engine and a 6p trans....
Im just not sure yet to pull the trigger in buying an 04. Even tho i fell in love with the one i seen yesterday but who ever had it befor used zip ties to mount the rear bumper (insert your smily here)

superhypered

nothing wrong with zip ties. i got one holding up the bottom of my driver side exhaust shroud. I hope all goes well for the OP, if it hasnt already happened.
I currently have the lowest car on the food chain of RX8s (04 4-speed A/T), but so far, she's done good at 87k miles

Grimm0ne

iTrader: (3)

In the DSM world i could of seen this. but a 2004 with zip ties where the bolts should have been on the bumper... dont think so

and i'll be there with you, as I want a manual but no one in my family with give me help to A: go pick it up/drive it home B: give me a few lessons

so im getting an auto for now...

i just need more input on the swap for next summer if i grab one that is...

superhypered

well theres nothing wrong with an automatic. I asked my dad why people thought it was faster, and he told me that drag cars are automatic.. They dont have time to shift. Then I asked my friend about manual vs auto and that drag thing, and he said the drag cars use a racing shifter.. which I asked him if it has a clutch, and he couldnt really answer it.. JUST something to think about I guess. My car gets me from point A to point B without having to worry about stalling. and my tires will last longer because im not able to do a clutch drop, so thats a plus for me, tires are expensive..

and about the zip tie.. it was in a rear collision that cracked the bumper paint and broke the bottom mount of the exhaust shroud, so my dad helped drill a new hole into it and we zip tied the shroud to the bumper. lol i dont think the whole bumper should be zip tied on though..

Grimm0ne

iTrader: (3)

yeah, things like that, zip ties till you get the time and parts to replace/fix.. but the left rear was zip tied where the OEM bolt should of been... and the rear bumper would of needed repainted...

So i'm hoping tomorrow the dealer calls me to finalize the one i've been keeping my eye on.. will see.

9krpmrx8

iTrader: (46)

Sounds to me like the OP had a handle on this. TCU (6 port auto tranny), 6 port tranny (maybe not needed), 6 port engine, 6 port AT PCM. Seems like a hassle to do if you are in the US when you can get a 6 port AT for cheap.

superhypered

my rear bumper is messed up too, front bumper chipped, large dent in driver side fender so im getting a body kit and doing a full paint job, same yellow..
that reminds me, what color is this one you're looking at?

Grimm0ne

iTrader: (3)

Nordic Green Mica... love it! but i'm finding local 5spds but no one to go help me brining it home etc

superhypered

i was literally going to say "dont let it be green..." called it
at least we'll both be part of the 1-year, 1-color club..

Cylestyne

I didnt get around to doing this, there are too many ifs. The biggest complication seems to be getting the tcu to mate with the ecu. If I am going to be spending so much money I might as well as just buy a 6sp m/t freshly landed from Japan.

200.mph

iTrader: (9)

there are no 5sp rx8s in the states unless imported or swapped. i think you mean 6sp. any where in pa are you i live in nepa between scranton and the poconos, if you need a hand driving a 6sp home for you hit me up. i have one and could probably help ya out

Grimm0ne

iTrader: (3)

yeah, i should double checked, its a type-o... 6spd. I got the automatic one. But have plans for a 6sp swap (auto swap) down the road, but i'll keep ya in mind if i go the other route. Im in the williamsport area.

chaos84

I have a 4at.......Is it possible to just swap the 6port engine, ecu, harness etc by itself no transmission swap?

mdw1000

Not sure. I think you might have trouble getting the TCU for the 4at to talk to the 6 port ECU.

RotaryResurrection

iTrader: (3)

Possible, likely. Would everything work electronically and seamlessly with no codes or lights? Doubtful. Would you gain the extra power of the 6 port? No...the auto trans cannot handle the high revs, and the high revs are what allows the 6 port to make the extra power.

A 4 port at 7k makes about 190hp. A 6 port at 7k makes (probably) about...200hp. Maybe slightly more. But not 230hp that people expect from it. IT only makes that at 9k. But the auto trans cannot handle 9k, and that is why the auto models shift at 7k (and why they put the low power engine into it to begin with).

It would be interesting to find out 1) whether the 4 speed auto trans TCM would allow the 6 port engine to rev to 9k, and if it did, 2) how long the 4 speed auto would last before grenading itself.