BryanH

I have at least one Viper, one Ferrari, and several Corvettes on my autocross "kill list" with all of 90hp at the wheels in my car.

Ph3ar my 80ft-lbs of torque. :p

rx-8_or?

People buy Rx-8 for its style, handling, and Speed(believe it or nOT!)
So why can't someone focus on speed??
One can say 6.3sec is fast, someone else might think 6.0sec is fast, and another guy might think flat 7 is Fast, everyone should have their own opinion, nobody should tell someone else "Rx-8 isn't the car for you " if it doesn't make eg 5.9secs.
Not a lot of us will make the top stated mag time actually, but bragging rights are also important, nobody wants their nice car to be laughed at, even if you don't care much , everyone is still hurt, even a little bit, when they're laughed at.

Also, stop saying someone is a troll or make statements that are troll-like. If they really are a troll pity them, they have nothing better to do than bashing Rx8?
If they're not and you INSIST they are, well you SHOULDknow how they'll feel.

It is sad to see a member saying things to hurt another member.

sheylen

Well I have been reading this forum and I would like to defend Hercules. He was just trying to explain politely that this car does not deliver the best straight-line performance per dollar. And if that is your main priority in a car, this car is not for you. Then somebody tells him: “Shut the hell up”. I understand that Hercules becomes angry and defends himself. Please guys tone it down a little, this has been an excellent forum and keep it that way. Regards.

wakeech

yes, precisely. it's just a bit of friendly, and true, advice.
of course everyone wants the best of everything, and there isn't anything wrong with wanting it, but the reality is that this car isn't going to be a "door-blower-offer"

animosities aside, the gripes of fritts and DonG35Miata and company are valid ones, saying that because it's and RX it should be fast. well, i'll tell ya: until the FD, the RX-7 had ALWAYS been MUCH slower than the Z car (240, 260, 280) in a straight line, with a far better grip on the road. this is the way it's been, and now the RX-8 is giving up two back seats to it. performance, in terms of whatever qualities and quanities you define as "benchmarks", is always a tradeoff. faster is more expensive, and more luxurious and utile is slower; sorry friends, you can't really have it all.
would it be nice?? sure. the MPS'll be mega quick (assuming of course they make one as fast as has been speculated), and that will satisfy Don's, fritts', and co.'s need for speed, and Immi's lust for exclusivity... just a trade off.

so, to get back to why this car mayn't be for you is because it's a comprimise between all performance factors, and that comprimise mayn't be what you want. that's fine, but unless you want to go to work on the car, it is what it is.

xkpbreaker

Well, with a lil extra money... I'll make the Rx-8 one of the fastest things out there!!:D

MPester

Well, all I gotta say is anyone buys this car for the whole purpose of straight line performance is a MORON. This individual obviously didn't do any research to spend his hard earned dollar.:p

xkpbreaker

I hope ur not refering to me cuz I thought we already went over this....

Kento

I think the performance will be closer to what you expected in your original post (0-60 times in the high 5s, quarters in low 14s or less). I had a chance to speak with Barry Winfield, the person who wrote the RX-8 driving impression article in C&D, since he's a bike nut as well. He told me that any numbers that were listed were just rough estimates, so there's no way we'll know for sure until the car hits the showroom floors. But he did say the car was blast to drive (he was at the original RX-7 intro in '92 at Willow Springs racetrack, so he has a good point of reference), with a very well-balanced handling feel that reminded him of the FD. Yeah, it may be not quite up to the straightline spec of other semi-competitors like the 350Z, but actually Mazda is looking for the 8 to create another genre of sports GT car. Not quite the two-seater sports car, but not quite the luxo-4-seater sport GT car either.

For those interested in serious performance, he said that Mazda is indeed working on the next gen 7. Mazda reps were going through great pains not to compare the new 8 to the FD (as well as say the 8 is NOT a new replacement for the 7), and quickly sidestepped questions on whether a sportier car would be appearing in the near future using the Renesis motor. Read into that what you will, but it's safe to say that Mazda won't want to come out with something that plays second fiddle to Nissan or Toyota. Obviously, the sales of the new RX-8 will determine whether Mazda will be able to go ahead with production of the new gen 7.

Oh yes, the turbocharging question. From what I gather, the new Renesis' exhaust gas temps are much lower than the FD's, which would hurt its ability to heat a cat con properly to pass emissions. In relocating the ports, Mazda engineers aided fuel economy and emissions, but got rid of the one advantage the original rotary had for turbocharging over conventional motors-- a surplus of exhaust energy to help spool up the turbos and heat up a cat con quickly. Some have spoke of larger rotors rather than another rotor as a method of hp increase. We'll see. Don't count anything out.

ZoomZoom

Welcome to the board Kento!

wakeech

hey Kento, welcome to the board.
i think i read that same statement about the "lower" exhaust tempuratures in the C&D preview, right?? well, Boogs, Grim, Max, Sput, T-Man, Dazz (if you're still around) or anyone who can help me with this, i'm pretty sure that the rotary actually has terribly high exhaust temps in comparison to piston engines... right?? of that i'm not quite sure.

one thing i AM sure of though is that Mazda's improved the path of expiration (with the double skinned exhaust header) to maintain gas tempurature from the combustion chamber, not to mention Boog's recent find of Mazda's "ground breaking" technological advancements in 3-way cat technology... can't remember exactly what it was, but it had substantial "eureka" factor to it... also, with the delayed expiration port timing, and the "fencing" effect the side ports have on keeping unburnt HC's in the engine to go another round, this engine is far FAAAAR better on emissions than the 13B could ever be.

about those side ports, too: at high rpm, i could see a slight disadvantage to the perhipheral ports as far as high velocity breathing (for powering a turbocharger), but with nearly 100% larger exhaust ports, it seems to me that Mazda could easily tune these ports to produce some killer low-rpm exhaust velocity for turbine spool-up. this less direct gas flow no doubt obscures flow, but i wouldn't say that turbocharging this engine would be any less effective than turbocharging a piston engine (where often gasses have to make very sharp turns to get out of the heads).

fritts

Here is my thought about turbocharging the Renesis. Most people that turbocharge the engine are not going to be running the cat. If they are that into getting performance out of the engine why in the world would they worry about the cat as it just hinders performance anyway.

I know some people might worry about smog and all that crap they have to pass. But from what I have seen most turbo kits are made for off road use only anyway, because they can't pass emissions.

I mean seriously how many 3rd gens can pass emissions tests with any type of upgrade.

Maybe, this is the reason why we won't see a factory turbocharged renesis as Mazda has stated, or it could be just another reason for Mazda to use a supercharger to pass emissions.

m477

They can pass just fine, you just need to run a hi-flo main cat (and make sure your plugs are good, and the car is warmed up, etc.).

fritts

I bet they can't pass a visual inspection with the most common mod of removing the pre-cats.

Buger

Hi Bill, :D

Previous rotaries had much hotter exhaust than piston engines. It is possible that the renesis exhaust will be quite a bit cooler during idle because of it's lean(er) burn capability and it's longer expansion stroke. Despite that, Mazda designed the new rx-8 catalyst to exhibit "superior resistance to high-temperature exhaust gases" which leads me to think that the rx-8 will still put out pretty high temp exhaust during full load revs.

A side intake engine that Mazda tested for a SAE article in 1996 had dual side exhaust ports that open 25 degrees later and close 71 degrees earlier than the single peripheral. The characteristics of the side exhaust ports mean that the temperature of the exhaust will be lower even without lean burn. Lower temperature exhaust means less velocity but since the new exhaust ports have more area open for a much shorter period of time, that would mean increased velocity of the exhaust pulses.

Mazda engineers previously defined the exhaust force that spins a turbocharger as consisting of two steps:
1. The "impact" force is when the exhaust gas strikes the blades
2. The "reaction" force as the exhaust gas continues through the blades and increases turbine speeds

The renesis is likely to have less impact force but higher reaction force (albeit for a shorter period).

I'm sure Mazda could design a twin-scroll turbo (not twin turbo) to take advantage of the renesis' unique properties. Perhaps KKMmaniac can post a diagram of the Mazda's previous twin-scroll turbo from the book "RX-7 - The New Mazda RX-7 and Mazda Rotary Engine Sports Cars"?

It sounds like Mazda is trying to go the NA route with 10mm wider rotors instead of turbos though. It will be the logical progression for Mazda to increase the rotary displacement:

10a = 982cc
(982 / 60) * 70 = 1146cc
12a = 1146cc
(1146 / 70) * 80 = 1310cc
13b = 1308cc
(1308 / 80) * 90 = 1471cc
15b = 1471cc (Mazda already made a 15a in the 70s)

Will the new Mazda concept be a 4th gen rx-7 with a 15b engine? or maybe a turbo?

Brian

koolaid80

There's all this talk by some members how the car is about handling, as opposed to straight-line performance, but how many of you actually go out and autocross regularly? Will that extreme handling performance be utilized making a right or left hand turn into a supermarket?

I don't think so.

Often times the only way for people to showcase the power and potential of their car is in a straight line duel. For anybody to demean these people's idea of fast is petty and unnecessary. Personally, I do attend autocross events, and the RX-8 will need more power in order to be competitive with many of the cars racing out there. A quick turbo upgrade is all that it needs to get in the game.

Quick_lude

If you REALLY attended parking lot autocross events THEN you would KNOW that power is the last thing needed on MOST of the courses. Tires and suspension is what usually seperates the best from the rest plus driving skills. Most auto-x courses are tight and engine power is simply not a factor. Civics and Miatas keep winning their classes against Corvettes Z06 and 350hp Camaros. So much for your "quick turbo upgrade"

Speaking from personaly experience I "use and feel" my suspension/tires upgrades all the time. Everytime I change lanes or make a turn, I use the "handling" Engine power upgrades are not used nearly as ofter as suspension.

wakeech

yup... i'd rather be on an independantly suspended 120 hp machine than a 200 hp live-axel-front-and-back setup too...

on a more serious note, i actually DO enjoy "flying" (at 35 kph in my Echo) around corners as i'm driving day to day...

KKMmaniac

"Perhaps KKMmaniac can post a diagram of the Mazda's previous twin-scroll turbo from the book "RX-7 - The New Mazda RX-7 and Mazda Rotary Engine Sports Cars"?"

Ok Buger:

I just got the hint. (I haven't been paying attention!) I scanned a bunch of crap, (twin scroll turbo and 12a turbo) from Mr. Yamaguchi's book, and zipped it into a file. However, it's almost a meg in size. Let me know how I can get it to you, if you want.

I don't have the technical patience (or smarts!) to determine if or how a turbo could be used with the Renesis, but I would think, side ports or not, some approach could be used to harness the exhaust power for a turbo!

wakeech

could ya hit me too??? andrew_keech@hotmail.com

danke.

Kento

This is where I see the new gen 7 going. It seems the manufacturers are starting to move away from turbos due to their increased complexity necessary to run properly under all conditions and pass increasingly stringent emissions requirements.

The only problem is that the even the new RX-8 lacks low-end torque, despite its top-end breathing capabilities. Winfield said that you really had to rev the 8 to get some good steam from the engine room, similar to the character of Honda's S2000. Yes, I know a lot of us could care less about low-end torque, but for a street-driven car, it's pretty much a necessity. Anyone who's enjoyed the quick spool-up and nice midrange pull of a sequential FD knows what I mean.

Crank(whoops, I mean rotor)-driven superchargers offer an alternative means of increasing power, but they also bring some of the same problems that the turbos have, plus some additional ones like low-end power losses from drag/friction (superchargers work OK on bigger V6s and V8s because the engines already have decent torque; the rotary would probably struggle with the added frictional losses). And there still is the nagging dilemma of the lower temp exhaust gases to properly heat a cat con to deal with the additional exhaust gases generated by forced induction.

Whatever the case may be, I'd still like to see Mazda stick it to the other manufacturers and blow'em out of the water with a pure, no compromise sports car that offers supreme performance for a reasonable price.