Hello everyone,

This is my first post and i figured i'd put my question here considering i kinda came up on a mint' 05 white Rx8 AT with 35000 recently serviced miles on it so i figured i wanna start playing with it.Please bare with me,Kinda long,but here it goes.I did alot of research on these forums first before i asked this question.I looked up what i had and what other models of rx8s came with to learn i have a 4 port 4 speed auto,the least desirable of models, relatively speaking based on MT to AT numbers that have been modded,but i love a challenge.I have worked in the import industry for about 13 years and played with most of the "typical" builds(hondas,nissans,and toyotas) hands on from building the blocks,machining,and fabricating other things here and there,but these are all piston motors,my last car being a GT35r '06 STi laying 425wrhp,on relatively low boost.I'd say I know how about 98% of all things automotive work.The 2% i dont know, being rotarys'. I know the basics of rotary motors,in theory,but never hands on built or tore-down one.So the question is,if you take apart a 4 port and build it(upgraded apex seals,blue print and balancing,etc.)and added a big turbo and the right amount of fuel needed,all fabbing, fuel management,and tuning done in-house(and assuming the auto trans has been fortified),and money not really the issue,theoretically How much power would it make? ?and if it can't or could not make good horse numbers,why not?Sorry its soo long,but i had to ask,feel free to respond and open my mind up on what my plans are gonna be to make power,thanks alot guys.

~R

 

From all of my researching the most power you can safely get from a auto i thought was to be around 300hp MAX, i dont know whether thats Whp btw. Since i have a 4-port auto and i want a manual really bad im just going to ask this question.

Why do you want a auto 8? This sports car is so much faster in manual, trust me ive been in my auto 8 WOT and ive been WOT in a manual and it just doesnt make sense how 40-50 hp = 11/2-2 seconds faster to 60... so in my opinion if your going to be breaking it down, get a manual, because its alot faster and way more fun. Anything that wouldnt be working properly i assume you'd fix anyways right?

 

Curious to see what the 4port can do,not really worried bout the trans,but why does everyone say the AT has a 300hp limit?luv to hear input.thanks again

~R

 

How many, I dont know... But a lot ^^
Here is an 312hp 4port 5MT
http://www.youtube.com/watch?v=3ePDo...eature=related

 

I get tired of hearing " I want a manual" - sell what you have buy a manual and dummy up. I can't understand why in hell you would have purchased an AT and then cry about it or is that all your mommy will let you have?
I'm working on it right now - just rebuilt by BHR, Ported by BHR, FId by Pettit, engine management by AP and tuned by MM. The stock tranny is holding up great. One of these days I'll get it dynoed and see what I am pitting out/down. Big Turbo? well ask" 09 Factor" he has a small turboed AT. He would be better to ask about the large turbo.

 

The 4AT trans is probably the beefiest of all the RX-8 transmissions. Not sure how much power total it can handle, but most of the transmission failures have been reported by the 6 speed MT guys.

 

You are going to hit a lower limit of airflow on the 4 -port than the 6-port, so you can only go so big with the turbo. I don't know enough to know what that is.

 

Wow,this is interestingi see that in europe,they(in general)can create 300+ pretty normally under boost on a 4 port,auto or manual.And from what i here,most of the 4 ports that are under boost(T or S/c),are stock.Reason being to me,that no one here wants to experiment on it cause everyone says get 6port and swap the trans,,warranty or uncertainty,or they're trying to push the limits and see how far it will go, before the "ah-oh" happens,.The trans im not really worried about,(it might need to be modded,but so,it would be pretty much bullet proof after that and i'd have a higher stall to launch and whatnot.Autos have been around along time,used in very high horsepower applications and if you look at anything really fast,(JGTC,BTCC,Formula 1,etc)they're all on a auto-manual type of sequential trans(faster shifts,less room for error.I here alot on here about Phil8 fast auto(which gave me faith),and others down to play with the 4p AT.Im glad there's guys like that, that arent," scared ".I hate being told,"no" or "cant do" because thats just another reason i have to try,and seei if it might work,..thanks for the replies,more are always welcome.

~R

 

Well I have a 4 Port AT. Mine is running nitrous. It has 183 RWHP.

It's funny when people say that the 4 port can't handle that much boost.
The engine has the same internal volumetric efficiency as a 6 Port. So going boosted is going to net similar results. Now the intake is different and the intake volume capability is different (NA). Difference in the intake runners and cast iron ports..
But boosting a car is over riding the limitations of the intake volume.
You can push the same volume (CFM) of air through a large pipe as a small pipe. The only difference will be the amount of pressure (Boost) needed to do so.

 

Easy,

Yeah, that was what I was trying to get at - 2 less intake ports. You just expressed it much better than I ever could

 

RotaryJunky,

I personally think it is fun to try to improve whatever you have. No matter what car people have, they can always be told to go buy a faster car instead. For example, we could tell the MT guys "go buy a vette, mustang, etc, etc".

For what it's worth, according to mac11 and Red Devil (the guys who did the work on my custom setup, who I owe a debt of gratitutde), feel that my new SC running at just under 4psi feels very similar to a MT now as far as acceleration goes. That is with 4psi non-intercooled on an extremely conservative base map. Soon I'll be putting the 5psi pulley on there and getting it tuned, so I should be faster with my lowly 4AT running a very low amount of boost.

 

thanks for the replies guys.Easy puts it right,that even a large amount of volume can be pushed through a small openning,it just takes more pressure.I also think that the 4 port will make a flatter/broader power band due to the intake/exhaust port ratio(4 in,3 out vs. 6 in,3 out)being closer to 1:1.This is my theory because of the high horse/low torque numbs on M/T's and high tourqe/low horse numbers on A/T's. Intake manifolds can be made,if done right for F/I to flow the way it should too.I just figure that other than the 6 to 4 port and tranny,obviously,the Rx8's are identical,and the story of the 4 port being weaker,being a thing of the past.love to hear feedback,thanks again.What you guys think..?

~R

 

The main reason i want to boost this 4 spd,is proven through experience,the fewer gears you have,the longer they have to be,thus putting us in boost longer with fewer shiftsthis is starting to seem like fun...

~R

 

From What I have read, the 4-port actually makes more power than the 6-port up to 7000 rpm. The difference is the longer gears.

 

[quote=Phil's 8;2932565]I get tired of hearing " I want a manual" - sell what you have buy a manual and dummy up. I can't understand why in hell you would have purchased an AT and then cry about it or is that all your mommy will let you have?


Ok Phil first of all i didnt buy a automatic, this auto 8 was the only thing my "mommy" gave me... First of all im very fortunate about this car and how unique it is, how rare it is, how fun etc..., but second of all ive been into cars since i could walk and the fact that all of my friends have manual GT's with LSD and all of those nice features, I dont, and to be honest im kinda of jealous... I have a 4-port BASE model. Everything from suspension to LSD to rotor sizes are different in my car, now since ive always been a car enthusist ive always believed that a true sports car is a manual, sorry to hurt your feelings but this is what i believe. Now you can say i bitch and moan all i want but i hate the fact that i can get beat by the damn Toyota Prius over there next to me or the Civic over there with the 3 wing spoiler.., the guys with Manuals say/complain they arent that fast at all, but wtf does that mean i am??? If im 11/2-2 seconds slower to 60 then i must be very ******* slow, the manuals are much faster stock than automatic 8's, granted you cant say **** because you have a S/C and you auto isnt "slow" anymore. Im not bitter about my car because i love it to death but when you've always wanted a manual like i have and idk... some features more than base, idk there is nothing to compare it to a manual 8. Hell id take a manual 8 sport model, i just want some damn 18's, LSD, HID's, and idk, more acceleration? A faster 0-60 time wouldnt be so bad, i dont like to get beat by the riced out honda. Now dont think i race my 8 because im 16, im not stupid. But when all of my friends see my car they think "damn, that must be pretty fast" then i just remember i just got beat by my friends moms Ford Taurus crossover. I mean come'on with how sweet this car looks to get beat by a Ford Taurus?!?! You gotta agree with me thats pretty Gut Wrenching... Atleast with the manual Id feel better about my car not getting beat by the Prius, To me thats a little embaressing, and you can hate on me all you want but manual 8's are called slow already, how do you think i feel??? im a second or 2 slower... I mean if i didnt have a base model maybe i wouldnt be saying this or if i had a 6-port auto with LSD but i just would love to have a true sports car (stick) with LSD, 18's and idk a sunroof? Some people want more than base, thats why they get the the sport model or GT, they want more features...

From What I have read, the 4-port actually makes more power than the 6-port up to 7000 rpm. The difference is the longer gears.
__________________
Yes i believe we do but the fact that you can launch the manual still makes it faster... and gear ratios are different which also help it with speed etc...

 

Hey rotary junky, im glad that you have an AT 8 and your going to experiment on it. I really love my AT 8 and i would love to turbocharge it but i figured it wasn't worth it because its not a MT. But hell, you and some other guys on here made some really good points. its all science. Well all i wanna say is that i would like to know about any progress you make or have made already. I'm not much of a follower but i would sure as hell follow on this one.

Thanks,

-DON-

 

[quote=WTBRotary!;2934272] I guess what irks me the most is some of the at owners, like you, would rather people feel sorry for you than you taking the rains and make your car the equal or better. But no you'd rather we feel sorry for you cuz you get beat by a kid on a bicycle. My 8 came with everything that Mazda offered and especially the AT, I ordered it that way, base model or loaded all have the same engine. You have nothing more than I have except for lack of desire to improve it. I am not really sure you know what a true sports car really is. All you need to do is read your post and come to the realization that you are crying not trying.

Look at Easy-El, 09 Factor, mdw1000 and so many others that are working with their ATs. Rotary Junky is asking the questions and I would be surprised that he will not be satisfied until he has made improvements.

 

Thanks to everyone for the responses.After reading,researching,and seeing other AT enthusiasts' do it at we speak(F/I modding),there still is kind of a new frontier out there waiting for us AT owners.Probably a little more for me, being newer to owning my Rx8 and tinkering with this renesis 4 port.I believe good rwhp numbers are attainable with the right formula and safety measures taken.I will be doing my research in the mean time and making calls and emails to figure how im gonna go bout this.Trust me,you guys helped me clear air so i could take a deep breathe,and start some work.See you guys around these threads for now on too.

~R

 

^^^I am not reading all of that. But at first glance it looks like another autotragic, have-some-cheese-with-your-whine, ATs are just as good as MT-fest? Can anyone confirm that as the case?

 

You know some of us looked at the 4port motor and did not see any way, other than porting and lightened rotors, to really improve it but then again we may have been slaves to FI and overlooked something. I hope you do find some substantial improvements to the engine. be sure and post your findings. The tranny is a untapped resource with very little being done to improve the AT. If you going to look here, more power to you (I would be very interested).

No your wrong, just another MT lover who is crying cuz he has an AT and is unwilling to improve it. Almost as bad as a MT fanboi who reads AT threads and trys to post witty remarks- fail.

 

Subscribed
and to be filled in when my boss isn't looking over my shoulder.

Congrats on teh SC Mark!

 

The 4 port does not necessarily have the same volumetric efficiency as the 6 port. It has the same internal volumetric dimensions, but I believe that is what you were trying to get it.

As far as moving the same amount of air you just can't do that either, N/A, as you don't have 1000+ rpm on the top end, which is where the 6-port really starts flowing a LOT!

I'm not trashing on the 4port here, just pointing out where the inequalities truly lie.




The limitation of the 4port lies in the same place as the 6-port as far as ultimate power potential. Static compressions. You have 10:1 compression from the factory, which you can only do so much with on pump gas. If you want to get fancy and run meth or high octane fuels you can do some more but that is not exclusive to either intake configuration or the rotary motor at all.

If you want to put go right up to the upper limits of what pump gas is capable of I would expect to see the same 350bhp+ that the 6 port is able to do. This is as of yet untested on my end though. Just math, which doesn't necessarily always add up.

As far as tearing the motor apart and blueprinting everything....I wouldn't worry about it until you are doing a necessary rebuild after you blow it up. And from the sounds of what you have planned, you will blow it up. Will you gain some power from doing this? Probably a little, sure. Will it be worth the expense on a motor that has good compression? Probably/Definitely not.

From all accounts the Renesis takes detonation better than the previous REW motor but if you are detonating you're at risk of blowing your apex seals regardless of whether you have OEM seals or 3mm Ionetti seals. On top of that a well respected rotary race car tuner/builder I had a conversion with recently said he has tried everything under the sun over the years as far as aftermarket seals go and he "just" uses Mazda seals in all his builds now.

As far as the trans goes, I believe there was someone on here that had level 10 do a tq converter for them so they could spin the motor higher and have a higher stall. If you really are looking to dump money into the car and make some power this is probably a good idea. But getting into the trans is really unnecessary until you start making stupid amounts of tq - which is pretty inconceivable on a 10:1 rotary using pump gas. They 4-speed was sourced from the truck fleet overseas if I recall correctly. And I'm not talking about a pickup truck.

My only words of advice above and beyond the information posted above is this: have someone experienced in F/I rotaries do your tuning if you have never done it before.

Good luck.

 

Ok,after reading your points,this is how i see it...

first,the volumetric size is the same,and the exit flow is the same.The extra thousand rpm is pretty much attainable through a Cobb AP/Int-X.Just because the 6 port has the ability to force more air into the motor,it does not have an extra abaility to get rid of it.The static compression of 10:1 is also do-able.Back in da day people had this thing that anything F/I had to be low comp(preferably 8:5:1- 9:0:1),but after these setups were built,the majority had lag issues for using bigger turbos, NOS helping spool-up started pushing motors to there limits,so what alot of race engine builders do is raise compression to spool the turbo up and compensate with the right amount of fuel to not knock.As stating in the first question of the thread,fuel wasnt really discussed because it is relavent,question is what is the potential of a F/I 4 port motor.Another thing,im not to be rude,but "stupid" enough to go stick a GT35R/1000cc injectors/etc. or what have-you on my stock motor to test out its limits,low miles or not,i dont do anything without the proper precautions.After calculating,researching,communicating to others around the rotary world,I'll figure my own plan out,again Thanks guys for the knowledgeWill
keep y'all posted too..

~R

 

[QUOTE=Phil's 8;2934359]Dont forget about me!!!!! I am working on my AT too, IRS took my turbo!

 

the more we discuss,the more that be figured out...more heads are always better than oneFYI,this isnt a A/T are as good as M/T's,etc.this is a discussion on how we can look for resources and a little more know-how to try and create potential in our 4-port.and If i ended up getting a 6port ,i would've asked the same questions about my 6port,M/T or A/T,..ok.Cheers

~R