Triangul-8

I am disappointed in the torque of the 8's motor compared to my 93 RX-7 R1 (255hp/250lb ft. of torque). I would like to see the torque come back with the addition of extra rotors or turbos. I am not too worried about the price of the new 7 with turbos, since my wife's fully loaded out AT model cost comparable with my 93 more than 11 years later. Technology is a wonderful thing, BRING IT ON!
Hey Zero,
Maybe you should read the RX 8 brochure that clearly states that in the past they have built up-to 4 rotor designs. And if you look around you in everyday life you can spot technology that you couldn't possibly conceive possible, but it works, thanks to talented engineers, and deep pockets.
In my industry, Kawasaki continues to deliver the goods year after year getting considerably lighter, with higher HP's, tighter revs (16,000 redlines) on 4 cylinder engines, and yet continue to for the same or less retail price than the previous models.

ByeByeSaturn

Triangul-8, I think what zerobanger is getting at is that the Renesis comes with a complete redesign of the exhaust ports, placing them on the sides of the rotor housings, just like the intakes. If you have a rotor crammed in the middle, it's hard to vent the exhaust coming out of the side of the housing. Then again, they obviously have had to do it for the intakes, so who knows.

Oh well, I'll leave that up to the engineers.

rxtreme

iTrader: (1)

I would think it would be just as easy to manufacture a 3 rotor with the new side port and other Renesis technology as it would be to make the current 13B-REW with turbo. I mean, think about it, the research has been already done as far as the changes that need to happen. Much of the tooling and other manufacturing processes may already be there, as well: Mazda has already made a 3 rotor. And we know it fits into the RX-8.

The only downside of the whole thing may be weight. I wonder how much a 3 rotor would weigh? Maybe AcostaRacing can let us in on the weight differences in the 3 rotor vs. the Renesis. If Mazda could keep the specific output about the same, we're looking at around 320's or so in the HP department.

rx-7~rx-8

time will tell...

Jhouse

I think an NA car is more respectable than a damn turbo or SC car any day. BRING ON THE 15A

Japan8

As time goes on the likelyhood of a turbo goes down... why? MOre and more strict emissions that the turbo car just won't pass... not without some kinda breakthrough in cat technology.

On the other hand this makes for a difficult JDM situation, as all Japanese enthusiasts expect a rotary engine, especially the 7, to be turbocharged. To produce an N/A version might meet with a lukewarm reception. Honda has this problem with the RC211V MotoGP race bike. Honda fans see Honda and an inline 4 company, not V5.

What's likely? Come on... the 8 is rated by mazda at 238hp instead of 247hp like in Japan. I don't believe that the 350Z is the right or fair competition. The 8 has 4 seats and 4 doors. The Z does not. Same for the S2000. 2 a hardcore sports cars and the 8 is a sports sedan. The 8 is looking at cars like the G35 coupe, the BMW 3-series, Audi A4, Lexus IS300... these kinds of cars. Given that compeition... is the engine that weak? Hmmm. If Mazda really does decide to up the 8's power, I think we'll see a 1.5 N/A 13B-MSP. Which will then mean a 20B-MSP for the RX-7.

I think that's the factor everyone who keeps whining about turbos keeps forgetting about. If there will be a 7 (and if you want there to be one) the 8 cannot be more powerful than it. The 7 is the flagship car. I also believe that the 7 will be somewhat similarly priced... as some people will want 4 doors and some will want a 2 seater. Two different markets.

Just a little something for people to chew on...

CERAMICSEAL

Japan8,
You seem to dream some of the same dreams I do. A 20B msp would kill the competition; fuel economy is one of the only problems.
By the way I also own a Protege5,

JSE RX-8

i was hearing that HKS is in the middle of making a Twin Turbo for the RX-8 and that Blitz was working on a S/C for the RX-8 but i may be wrong. there are a ton of rumors right now but the spring/summer will be interesting for the RX-8 and the turbo and S/C packages that may be offered

Knerk

Question?
What would a bigger rotor do to gas milage & performance?

shawn81

aren't maxda speeds out there ... like rx-8 T with 300and some HP i thought i saw something ... but they are only in japan.. too bad for us

Equis

That thing looks ugly as hell, how is that going to be a winner!? It looks like a photochopped Mazda6 headlights, Pontiac Fiero Bumper on a RX8 body.

m477

Uhhh... twin turbo RX-8 and 20b Renesis?

You people must be on crack.

I mean everyone KNOWS that the new RX-9 will have a 6-rotor engine with at least 4 turbos and NOS as standard.

T.T.

I highly doubt that it will be twin-turbo charged. MAYBE a single turbo since that's what Mazda e-mailed me and said they were currently working on. I think a 15B would be a better choice though.

93RedX7

N/A should be a 1.5L Renesis w/ 11.0:1 compression.

A 3-rotor Renesis isn't that hard to imagine. The only differences would be the extra rotor and intermediate housings (duh), as well as making the end housings larger in order to expel the gases from the front and rear rotors. The front housing would take exhaust only from the front rotor. The front intermediate housing would carry exhaust from the front and middle rotor. The rear intermediate housing would take exhaust from the middle and rear rotors. And finally, the rear housing would take exhaust from the rear rotor only. The exhaust manifold would look like that of a four cylinder. Granted, it would take a bit of engineering, but I'm sure someone at Mazda's R&D has already thought of it. Just my $0.02

shelleys_man_06

Making a 3-rotor 13B-MSP sounds easy doesn't it? Have you ever thought about the massive heat transfer between the middle rotor housing and its surroundings? A 2-rotor engine already has a poor thermal efficiency compared to that of a piston engine, so why take a step backwards? In addition, 3-rotor engines are notorious for its poor feul consumption. The sheer output/displacement ratio would be lessened, and the extra weight would offset the 50/50 weight distribution of the car. Mazda already tried this method in the JC Cosmo, and the Cosmo has been dead for quite some time. Stop wishing for a twin-turbo RX-8. If you wanted insane power, buy an FD3S. I hear they're pretty fast . As for the future of rotary engines, I see an increase in displacement and compression ratio. Forced induction, though it has come a long way since 1992, is still a liability for rotary engines that Mazda cannot afford. After the FD's demise in 1995 (United States), the rotary engine program was reduced to about 6 people. This is coupled with the fact that the rotary engine is only 30 years old. It's still pretty much a novelty, though it has a winning pedigree. It will be a while before this engine shares the benefits of a piston engine. It's not the engineering, it's time and money. That's what Mazda cares about, as does every other automaker. They're not going to cater to a few people's needs. It's good to bring these topics up, because someone might be listening .

93RedX7

You definitely make some good points. However, you yourself mention the rotary is still in its infancy. Therefor, engineering improvements may allow a 3 rotor Renesis sooner than we think. One of the biggest resons the Cosmo is dead is because it was so damn expensive. You also mentioned fuel economy. That's usually the last thing going through my mind when I'm thinking about a sports car. I do agree with your point about not needing a twin turbo RX-8. A good small single would be sufficient. And I too hope someone important is reading these. :D

shelleys_man_06

Sensible buyers also look at fuel economy, as does the government. Do you really want to own a sports car with a gas guzzler tax amended to it? I say let the aftermarket sort the forced induction equation. Mazda is doing too good to screw up now. BTW, 93RedRX7, do you have any idea who sells the GT3540 turbine?

shelleys_man_06

I don't get the idea of a 1500 cc rotary engine. Does anyone know how to calculate rotary engine displacement? Okay, time for some math.

How do you calculate displacement in a rotary engine? It's actually a short algebraic equation. If you remember ninth grade math (hottest girl was Lydia C. ), this one should be easy.

Let's define the displacement V, so that

V=(3)(3)^(1/2)wR^2(e/R)

where,

w is the rotor width
R is the rotor center-to-tip distance. Think of it as sort of a pseudo-radius.
e is the shaft eccentricity

Note: The eccentricity ratio e/R, is critical to the successful performance of the rotary engine.

This math is all fun and games, but what does this mean in terms of increasing the displacement of the current 13B? Since the relationship between the left-hand side and the right-hand side is directly proportional, changing displacement is as easy as changing one variable.

The 13B's rotor width, I believe, is 80 mm (RG help me out with this). The easiest parameter to fix is the width of the rotor, since its dimension is independent of the eccentricity and the radius. It is, after all, the width (think in terms of XYZ coordinates). Say Mazda increased the rotor width to 90 mm. Easy as cake. Piece of pie. Now, after some plugging and chugging, not to mention finding the eccentricity and the rotor center-to-tip distance (figure it out), you'll get about 1600 cc. I use metric units because cubic inches are too archaic to me. In addition, I'm not going to waste my time converting. I hope Mazda is reading this, because I need a job.

T-von

Yes the 2 rotor has poor thermal efficiancy but if Mazda makes a 1.5L 2 rotor it will only get worse. Widening the housings will make it even less efficiant than a 13b version(cumbustion chambers already large enough). I personally feel that the current 80MM wide housings are at there limit when it comes to efficiancy. IMHO if Mazda wants to increase displacement, they should go smaller and build a 1.5L 3 rotor. They could use the 10A rotors and housings. Since the older 10A was a 1.0L adding a 3rd rotor would make it a 1.5L. With a Renesis 3 rotor based off of 10A parts, the engine really wouldn't be very large. Also having a thinner housings should improve the cumbustion efficiancy because the cumbustion chamber is now reduced in size. Now even though we have an additional chamber, this doesn't mean the engine would be more of a smog monster either. Look at the 8.0L V10 Viper engine? Think how unefficiant that engine would be if it was a 8.0L 5 cylinder. I don't think the 5 cylinder version would pass smog very well. Now do you guys see my point? To save weight, Mazda could easily use aluminum side plates, because this engine wouldn't be a high volume production unit. You would also have the additional power stroke advantages 3 rotors give.


Overall what I'm saying is that it's better to have more smaller chambers to use for cumbustion than to have two really large ones.

93RedX7

Not neccessarily. With 10A rotors, even 3 of them, the RPM's would have to be pretty high achieve a higher level of power than the current Renesis. That in itself, with more mass would create more heat. Mazda could use aluminum side plates, but aluminum expands under heat. They would have to plasma spray them with cermet, and that would kill the cost. Shelley's_man_06, I really couldn't tell you who sells just that turbo. If you knew the exact dimensions of it, you could probably get one from http://www.cheapturbos.com You're also right about making the rotors 90mm would create a 1.6L. There have been some really good points in this thread.

shelleys_man_06

Since it's basically a GT35 turbine and a GT40 compressor, with the ball-bearing option, I think, the overall dimensions are pretty big; the GT3540R is a huge turbo. It would be a tight squeeze in the RX-8's engine bay. ATP has the wheel diameters of the GT3540R. Useful, but those are the only real dimensions I could find as of right now.

93RedX7

You're damn right that's a big turbo. I think I found what you're looking for. It's at the RX7Store. Here's the link- http://www.rx7store.net/index.asp?Pa...ROD&ProdID=612

I realize that it's the kit for an FD, but I hope it helps. Although, I don't think it's the R model. Sorry if I'm wrong.

shelleys_man_06

93RedRX7, I believe that A-Spec, wherever they are, also sell the GT3540R. I wonder what kind of performance that would make? Yes, the turbo kit they sell at the RX-7 Store is a ball-bearing GT3540. I usually recognize the ball-bearing option when I see the R :o.

93RedX7

There's a thread at RX7club about a guy that just got his dyno'd. I believe he put 450ish to the wheels at 22 psi, but everyone was saying that he should be seeing a bit more than that. Yeah, I'm a little new to the whole turbo jargon thing. :o All I used to care about were my Hitachi twins, but now that I'm going single (sooner or later) I'm trying to educate myself about turbos.

shelleys_man_06

A good book to read would be Corky Bell's Maximum Boost: Designing, Testing Installing Turbocharger Systems. I am currently borrowing it from my school's library. I didn't know that the library had such good stuff .