I wanted to throw out a fact about the rotary vs piston debate...
 

That in its evolution, the piston engine has had tens of THOUSANDS of engineers developing, improving, and trying to perfect its design.

The rotary in its evolution has been touched by fewer than 100 engineers. And to make the progress they have with the limited funds, engineering talent, and apparent lack of widespread acceptance (though that may change with the RX-8!), it's doing pretty damn well with a 1.3L engine making 250 Naturally Aspirated horsepower.

Imagine tens of thousands of engineers working to improve the rotary, over the span of time the piston engine has had.

Which would be the better engine?

A debate that's open ended, let's all keep it clean and contribute! :)

you know, im genuinely surprised we still rely on fossil fuels running engines that turn out less than 50% efficiency. im looking forward to the day (hopefully in my lifetime) that any car with a combustion engine will be more of a collectors item as opposed to a mode of transportation.

wishful thinking perhaps, there are still segregated proms in georgia >_<

i really do like piston motors, they go from ridiculously finely tuned f1 motors to amazingly gas efficient 3 bangers to monstrous diesels. but the rotary i love most because of its finesse. one of the things about it i guess is it's much more simple than a piston motor, which, you could say, gives less room for improvement without some serious revolutionary ingenuity.

as for which engine would be better given the same amount r&d poured into them... i think it really does depend. the rotary is ingenious and very good at what it does. but with so many more parts and factors you can change, the piston motor is more versatile. variable valve timing is easier, 2 stroke is possible, you can bore and stroke piston motors easier (ie, same size block, still can use your same motor mounts).

i'd be real interested to see some massive 10L 4 rotor diesel motor... that would be...interesting :) so i guess the only conclusion i can think of is that the rotary would probably not have traded places with piston motors but probably would have had much more of an application niche...along the lines of (if you care to imagine) all the 2 stroke bikes/boats/snowmobiles were rotary instead and 4 stroke piston motors still had their share of applications. and now i've found myself rambling...it's late, i'll shut up now

I thought it was an excellent reply! :)

Mazda could build a 4-rotor turbo Top Fuel Dragster and try to beat the current 1/4-mile records (4.477 ET , 332.75mph).

http://www.nhra.com

http://www.topfueltour.com/english/teknik.htm

6000 hp Supercharged V-8:

I'm just a newbie when it comes to the Wankel. But I was wondering was the rotory engine ever applied to motorcycles? Well cuz since the motorcycle is pretty light as it is compared to your average automobile. And the wankel isn't all that torquey. But I don't know much about motorcycles either?

Any thoughts, info, facts? Please enlighten me with all your knowlegdes.

Y&Y,

Yes, the Wankel was applied to motorcycles. I forget which models (A Google search should help) but there were quite a few.

Also, the present, naturally aspirated incarnation of the wankel has relatively little torque. On the other hand, the turbo'd 3rd generation RX-7 had the same size engine - 1.3 liters - with 217 ft*lbs of torque. That's very reasonable.

You can build very torquey Wankels - the question is, how does the mpg and pollution compare to an equivalent power piston engine (I have no idea).

Hercules, Norton, Suzuki, a few others. Check out www.monito.com for more info.

I agree with Herc as to the relative lack of rotary development and there is potential in the design. However, I think there are limits to what can be achieved with the design due to its nature. How would you improve the basic design of the wheel? You can't. Porting, intake, exhaust, and materials used are about the only areas to work on in a rotary. The basic layout of rotor and chamber is fixed.

In contrast, in a piston engine you can change valve gear, valve timing, combustion chambers, more bore/less stroke and vice versa... I could go on but there are lots of areas to tweak with potential payback, compared to the Wankel's rotor and the chamber.

I'd love to be proven wrong, but I don't think a rotary without forced induction will ever make a lot of low-end torque unless you add a lot of displacement, which will really kill fuel economy as well as adding complexity. Those spinning rotors are thirsty. You can apologize for and rationalize it all you want, but in C&D's test the RX-8 turned in lower MPG than a G35 coupe that is much heavier, yet has more horsepower and almost double the torque. That is pretty sad. Yeah, the RX-8 was driven hard, etc... well, I am sure the G35c was too! No excuses. The fuel economy is sub-par for a car of its weight and performance, ESPECIALLY the real-world 7.5 sec 5-60 street start.

I am not bashing the car since I am no longer on board; it's just how I see it.

you're right about a few things Don, but not all of it. :)

it's true that you can't just change the geometry of the rotor and chamber willynilly as one could with a piston motor, but why would anyone want to?? as a performance motor, you can't get a better "bore to stroke" ratio, and it's impossible to fit more displacement in a smaller package (trust me, it is). the low mass of the moving bits in the engine and obvious mechanical simplicty really does lend itself well to high rpm operation (apparently the thermal efficiency increases with revs too)... in racing application, even the most basic steps to improve breathing (the invincible P-Port) has been relegated into submission, because it's just too unfair.

in the real world, though, it's true: the wankel is a bit too thirsty.
apperently the EPA doesn't believe Mazda's 20/30 (9.1/100km mixed, i think) claims, but until we get real-life reports from real people (HI JSG!! EASTMOONsan!!) we can't truely know... magazine tests are, well, magazine tests: i don't really believe that a few hours, or even a day or two, with a car is really enough to know it, it's basically just a first impression.
and BTW, you can still have a "real-world" 5-60mph start that's about 6 seconds: depress clutch while rolling -> rev motor to 7k -> drop clutch in first and roll the burn-out ;)

it's true that a low displacement engine will not make much force per turn, especially one with such a short stroke, but this is univesally true for wankel and piston alike. take a look at any 2.0L motor: does it produce significantly more torque than the RENESIS?? no.
even a really really oversquare 2.6L won't make 160lb/ft if it's stroke was comparably short to the wankel's (which is impossible, since the valves wouldn't fit into the combustion chamber, even at BDC ;)).

but, i know that with enough development the wankel could be made better: as good as a piston motor in fuel economy?? probably not. performance?? damned straight it's better, and always will be, hands down.

...i'm willing to bet $20 CDN that if the RENESIS (or wankels in general) stay in development with Mazda (with a real budget: not fanatics doing unpaid overtime, as i would) that a wankel motor will be the first 4-stroke (Otto cycle) engine to reach 10k at redline from the factory. eat it Honda, eat it good.

an interesting idea... i think Mazda'd be better off (obviously) trying to make a 6 rotor ;) ahahaha...

that way, it's a "sane" 1000hp per rotor... only... ;)

edit:
let's see... 6000hp * 5252 / 11000 rpm = 2864.7 lb/ft / 6 = 477.5 lb/ft/rotor ... CHILD'S PLAY!! ahahaha...

Ummm, there are plenty of 4 stroke motorcycles with redlines in excess of 10,000 rpm.

I will send you an e-mail as to where you can remit payment of your $20 CDN.:D

oops!! i forgot to add the PASSENGER CAR MOTOR part to the "4 stroke" bit. :p

He got you fair and square, Wakeech... pay up!!!!! It's only $ CDN anyway- only around $13 US. Do the honorable thing and puy, just don't wager next time...

Why would one want to? Well, in piston applications an engine designed to be more of a torquer can be given a longer stroke, a high-revving HP mill, a shorter stroke. Just as I was saying, more options for the engine designers. If a Wankel with a longer stroke for more torque could be developed, it could find itself in other applications besides sports cars. And high revs are not desirable all the time. If I was getting the RX-8 I'd trade 1,000 rpm of redline for 25 more lb-ft of torque under 5,000 rpm. (BTW my Cooper S was completed Wednesday! :) )

Imagine: Mazda is going to go ahead and introduce an Amati line after all, starting in 2008. The flagship will be an S-Class sized sports sedan weighing 4,000 lbs with a three rotor powerplant, or 4,200 with a 5.5 liter V8. Horsepower is comparable at 330, but the V8 makes 350 lb-ft of torque@ 4,000 rpm and the 3-rotor Renesis makes 250 at 5,500. Peak HP is achieved at 5,500 RPM on the piston motor, 7750 in the 3-rotor.

Which engine has the best chance of making the car successful? Sure, all of us would take the 3-rotor with a six speed (if offered- what a car!), but the general public would want an automatic, and in that case my money would definitely be on the V8.

I am sure Mazda will surprise us with future developments, but as I said, other than intake and exhaust tuning, the Wankel is a lot like the wheel in that the basic design can't be improved upon, or developed further. It will take a real breakthrough for it to be competitive with the piston engine in automotive applications other than sports machines.

oh no no, i'm not saying it's not a niche engine: it most certainly is, and that's why i love it so much...

yeah, i'm not some kind of anti-piston fanatic, i'm just a simple rotary lover, and i love it because it's maybe the single best architecture around for a performance motor...

btw, that 2.0L 3 rotor would have to be in a pretty sorry state of tune to make only 330hp :p

...and about the $20: i'd send it, but Lou hasn't mailed me yet like he said he would... but i really did mean passenger cars specifically, but i was snoozing, so i guess i lost. *shrug* :)

why's that? 1.3L renesis makes 250, or if you wanna break it down, 125 per rotor. 330 for 3 rotors is 110 per rotor, that ain't that bad at all considering you are no longer counter rotating the rotors and it's not as well balanced as a 2 rotor.

I believe there are still a few more areas that can be researched, maybe increasing compression ratio and using direct injection just to name one?

I love it too and see, I would like to see it move BEYOND the niche. Remember the NSU Ro80, the Mazda RX-3, 4, PU.... OMC rotary outboard... rotary lawnmowers... rotaries everywhere. I don't think we will get to the point of that much rotary proliferation again as many manufacturers have made their minds up against the rotary, but with a breakthrough that improved fuel economy and torque we could see more rotary applications such as a RWD Mazda sports sedan to compete with the G35/330i/IS300, aforementioned rotary luxury car, a modern-day RX-3 (someone brought this up eloquently) etc.

Good point- the kickass Mercedes Rotaries that made gobs of horsepower alll had direct fuel injection, and I think peripheral ports on intake and exhaust. Who knows what would happen if direct injection was put on the side-ported motor?

Mazda claims about the new rotary's improved efficiency are overblown. The engine is thirsty, as they have always been. In the fnal equation I think it is this thirstiness that is the Wankel's biggest drawback, followed closely by lack of low-end torque. In fact, the two are related because if the Renesis had more torque, you wouldn't have to spend so much time in the top part of the power band. Lick the fuel economy problem, and then you have it made. The engine can see more applications than it has before, and BIG rotaries to power that luxury car could be produced. Perhaps something with 3.0 l of chamber volume as opposed to 1.3 today, all out of two rotors. No torque problems now... what a beast that would be!

BTW, I of course know the RX-8 is intended to compete with these cars. What I was thinking is something a bit more conventional. A lot of buyers will not consider the RX-8 a direct competitor because of the size and layout of the car, which is more sporting than sedan.

I can't take money from a poor ass college kid. Take the $20 and add another $20, drink till the women are cute and take one home and show her your knowledge of the Wankel.

I too would love to see a larger displacement rotary even at the expense of some of the rev range. A 1598 cc rotary with the efficiencies of the Renesis could produce 260 hp @ 7,200 rpm & 200 lbs-ft torque @ 5,000 rpm. This is still a high revving engine with a redline at maybe 7,700 rpm. This engine can be made with the simpler two stage induction system of the low power Renesis. I see this as the perfect sports car engine. Smooth. Great sound. Good but not great torque. Good but not great power. Super lightweight. Decent efficiency. No cost increase over the Renesis, except for all new tooling (that is a real big except).

I think the future of the rotary is bright. Big strides in torque, power and efficiency can be made if someone can develop variable port timing and geometry. Don't laugh. It can happen. I know because I am looking at a sketch of one at the moment.

3 rotor engines that I've seen make in the neighborhood of ~500 horsepower and still weigh less than your typical V8 engine.

Thing is though... they are thirsty bastards :)

variable geometry?? heh heh heh... whose sketch?? yours??

btw: i don't need the booze to get the women i take home "look pretty" ;)... not to mention the summer job has made me anything but poor ass :p

...would ANYTHING that makes 500 hp not be a thristy bastard at WOT??

Good call, lou.

Make sure you show her the E-shaft and your high RPM.

Group C Sportscar Comparison

_____________ 1992 Mazda MXR-01 _____ 1991 Mazda 787B

Engine _________ NA 3.5-liter V-10 _________ NA 4-rotor

Le Mans
Qualifying Time _____ 3:34.329 _____________ 3:43.503


http://wspr-racing.com/wspr/results/...emans1992.html

http://wspr-racing.com/wspr/results/...emans1991.html

Mazda shows that a piston car is faster than a rotary car.

1992 Mazda MXR-01

ahahaha... i knew it, i KNEW you'd post something like that... ahahaa...

...i'm looking into it. omfg... ahaha... the only reason that Mazda used the piston engine there was because they had to: the year after the 787B's COMMANDING victory the wankel engine was disallowed :p

thats also 10 chambers vs. 4 so giving up 11 secs does suck but its not too bad.

...actually it's 10 chambers vs. 12... the 11 seconds isn't in the engine alone.

...haven't gotten off my lazy (metaphorical) ass and researched rule changes or changes in Mazda's racing program, staffing, partners, difference in weather conditions, track/racing circumstances, or anything like that yet... and hence am completely unconvinced that the rotary engine (which was banned the year following its victory, and slowly deregulated back in) is the big difference there.

This is the part of the RX-8 I am looking forward to exporing. I'm anxious to explore what power & mpg I get with normal commute driving, and then see the difference under aggresive useage.

I believe the RX-8 will satisfy my needs under both driving situations, which will truely make it a remarkable driving experience.

I think rotary is an interesting technology, it functions like a automobile version of the motorcycle two stroke engine: High revving, gas/oil hungry, low torque, high horsepower, and relative simple design. To that extend, I'd say the rotary has more potential in small light cars and motorcycles.

You have to understand that Mazda holds the patent to rotary engine and they are not going to make this technology an open source. Imagine if a company like Honda gets a hold of rotary technology and builts one better than Mazda.... that would be the nightmare scenario for Mazda. Rotary will stay in the niche market because it is an exclusive technology, and applicable to a small number of specialized vehicles. Overall, rotary engines are more expansive to built (calculating R&D, manufacturing, parts sharing...) less confident inspiring, significant less torque and difficult to repair due to limited knowledge. To top it off, the general public were not very impressed by the reliability of the last rotary engine available on the market on the FDTT. (I know about the NA arguement, but most people wouldn't care)

i'm gonna have to punch a bunch of holes in the stuff you're saying, but not to be a jerk ;)

first off, the wankel motor is pretty thirsty fuel-wise, but it's a performance motor first: i'm not going to make excuses for that. the RENESIS has come a long way, but it's a performance motor first. the analogy between 2 and 4 stroke motors is, well, alright, but it's really like neither... in fact, i'd say it combines most of the best attributes from both, has a few unique advantages in itself, and but, i have a problem with saying that it's "oil thristy": this is just not correct. it does meter in a small amount of oil while the motor is running, which is purposefully burnt off as you know, but to say that its "thirsty" is a gross overstatement. the RENESIS is suppost to consume it at something like 1q / 10 000mi, which isn't half as bad as many normal econo-box engines as they get older, and consume oil as the ring seals weaken a little. its not a big cost issue, and something which has been refined a great deal too (from trickling down the carb to meter'd-direct-injection), and ought not to be a problem.

secondly, the wankel-type architecture has been fair game since the 60's. GM, Mercedes, and many, many, many-many others HAVE built (or at least tried to) rotary engines, and failed... to an upstart, know-nothing little Japanese car maker out of Hiroshima (3 guesses). Mercedes actually had a really rippin' 4 rotor, and GM made a rotary engine for the Corvette which never saw production, but it was Mazda that beat them all to it (by a lot) to get it to get it to work, get it into production, and get it to last.
now, of course anyone could again pick up the idea and try and build one better than Mazda, and i'd be all for it, but the problem is that Mazda has all the patents on all the right ideas, and is decades' worth of steps ahead of anyone else in terms of human capitol and patents on all the nifty stuff that makes the RENESIS the RENESIS.

lastly, yes, the wankel engine will probably always be a niche market engine, as a performance motor. this is because it's what the motor does best: burn tons of gas fast, in a small, light, and simple package... in fact, that's why i like it better than the piston engine: it's far better at it.
i'm lost as to why you say it's more expensive: the official statement from Mazda is that building the RENESIS, by hand, in its Ujina factory (or wherever) is cheaper (at least not more expensive) than building the V6's they put into their 6's. 'nuff said.

it is harder to find a guy who can tear down and rebuild your engine 150-200k miles down the road, if you wanna do that before it breaks itself, but its not like none exist anywhere. unless you live in the boonies (which i doubt anyone who's going to buy a $30k sports car is) there is one in the nearest urban centre. trust me, there is. aside from that, maintenance isn't rocket science. change the oil, filters, plugs, wires, coolant, misc lube, wipers... uhh... i mean, none of this stuff is different between a piston engined car and a wankel engined car. it's not that big a deal, or at least shouldn't be a deterrant to someone seriously considering the car.

the low torque comment... ouch. i know, i know, lets not all get into it, but for those who're new (welcome) you can tune a motor for low rpm operation, or high rpm operation. this is a performance motor, is only 1.3L in displacement, and revs to 9k rpm. it's a short stroke (10mm, yes, 10mm), "big bore" (it's really really oversquare) motor, yet makes 160lb/ft of torque. considering the last 13B made about 160hp at 7k rpm, and 140lb/ft of torque at 4k rpm, the RENESIS is a freakin' monster... no displacement increase, no big secrets. it's all in the side-ports. anyways, no, the geometry that Mazda has opted for isn't condusive to stump-pulling torque, but that's what revs are for :p.

the public may not have much confidence in the motor, but they will see, they will see. for 12 years the RX-7 reliably provided fun at a reasonable price, and only 3 model years of production won't completely erase that reputation Mazda has (with mucho credito for the Miata) for building good sports cars. in time we'll see, they'll see, everyone will see how this motor does.
sure, there'll be sh*t disturbers who claim to buy the car and storm onto the forum and just spout putrid things about whatever they can from every oriface, but they'll (hopefully) only be individuals. *shrug* now's the time to just wait and see.

I agree with you wholeheartedly from a performance/racing perspective that the rotary is king. Pound for pound the piston engine can not produce nearly the same amount of power. You can produce the same amount of power (though less torque, but its not as big a deal on a racetrack) from a far smaller engine that gives you a lighter and better balanced car.

Unfortunately, in the real world fuel economy IS a limiting factor. There is the gas guzzler tax in the USA (that's ridiculously low at something like $1,000), but more importantly the CAFE standards. I think if they went with a significant increase in displacement on say the next RX7, I think that could be a concern (I know SUVs are currently measured on their own, but I thought I saw some proposed legislation that would include them with passenger vehicles, but I could be wrong). Of course, the average Joe who buys it could be concerned (as we are seeing with some people on the RX8). Maybe they can use a 1st to 4th shift like Chevy does on the vettes, but I personally just don't see a NA rotary with a large increase in displacement (unless there is a magic bullet breakthrough in fuel efficiency). An exotic with limited production could get away with that consumption, but i'm not sure about a $35-40K sports car? Thus in the real world where fuel consumption can not be absurdly below the competition, the NA rotary engined car will be at a power disadvantage (even on the track).

I think the only choice is to go with a super light car with a similar displacement to improve acceleration and keep fuel economy from becoming ridiculous compared to the competition. On the other hand, perhaps they can increase the compression ratio, but I'm not sure if they can do it and keep the engine reliable?

Wrong. The RENESIS is smaller and lighter than the nearest piston equivalent, the F20C, but produces MORE torque. And more power. And gets better fuel economy.

Sure you could try to compare it to some big V-8 or whatever, but that's really apples to oranges...

Quote:

---

but I personally just don't see a NA rotary with a large increase in displacement (unless there is a magic bullet breakthrough in fuel efficiency).

---

There is. It's called less weight. A 2500lb RX-7 will have great (for a sports car) fuel economy, even with a 1.5 - 1.6 liter engine.

Also, a 1.6 liter Renesis even in the heavier RX-8 would still get about the same fuel economy as the 350z.

I said an advantage of a rotary engine is that it can produce the same amount of power from a SMALLER displacement, but it will have less torque. The S2000 IMHO opinion is a lot closer to its theoretical maximum output than the renesis is so its really not an apples to apples comparison. Let's use the 2.6 L equivalent piston displacement (I know some argue for 3.9 L). If so, all other things being equal, you'd probobly have greater power from the rotary, but greater torque from the Piston engine (i'm sure it would not rev as high), but on a racetrack the rotary would be superior. However, this was not the point of the post.

QUOTE]Originally posted by m477


And gets better fuel economy. [/QUOTE]


The renesis does not getter better fuel ecomomy than the F20C (18/24 per EPA for the Renesis and 20/26 for the F20C). The F20C seems to do better than the EPA estimates in the real world (I have seen several owners on www.s2ki.come get over 30 mpg on the highway while I have not seen figures like that from Z owners - the Z has the same EPA estimates).


[/B][/QUOTE]

Well less weight certainly improves fuel economy, but I don't believe that the fuel consumption from an approximate 20% increase in displacement is going to be more than offset by that decrease in weight.

QUOTE]Originally posted by m477

Also, a 1.6 liter Renesis even in the heavier RX-8 would still get about the same fuel economy as the 350z. [/QUOTE]
[/B][/QUOTE]

Hmm...so this 1.6 liter renesis is going to get better fuel efficiency than the 1.3 L current version?? :confused: The Z already gets 10% better fuel economy!!!!

Now you've gotten totally off track. The point was hp and torque PER POUND, not per liter. In which case the renesis beats the f20c at both. Also FWIW, SAE, whose job it is to set standards, considers the displacement of the renesis at 1.3 liters so your assumption that 2.6l is some sort of universal standard is flawed, but as I mentioned, displacement isn't relevant to the current discussion.

Quote:

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The renesis does not getter better fuel ecomomy than the F20C (18/24 per EPA for the Renesis and 20/26 for the F20C)

---

Um, I thought it was 30mpg highway, at least that's what I've seen in every printed publication for the past several months.

Yes, I agree with you that FOR ITS WEIGHT it should produce more power and torque (though both would not produce significant amounts at this displacement) than a piston engine of equivalent weight. The assumption of a 2.6L equivalent piston displacement comes from the folowing linked thread:

http://www.rx8forum.com/showthread.p...t&pagenumber=1

The bottom line is that the rotary is better from a racing standpoint in that you can produce more power from less weight.

However, the point of this post was to say that in the real world...the rotary's poor fuel efficiency limits its ability to compete with more fuel efficient piston competitors. Thus, its going to be at a power disadvantage with its competition as I think has been the case for the 1st and 2nd generation Rx7 and the RX8. A couple of ratios can make this point more clear:

Average EPA Fuel Economy/Road and Track's 0-60 and 1/4 mile times (higher numbers equal more efficient):
0-60 1/4 mile
350Z: 23/5.6 = 4.11 23/14.3 = 1.61
G35 Coupe= 23.5/6.1= 3.85 23.5/14.6 = 1.61
WRX 23.5/5.7 = 4.12 23.5/14.4 = 1.63
RSX-S 27.5/6.7 = 4.10 27.5/15.2 = 1.81
S2000 23/5.5 = 4.18 23/14.1 = 1.63
EVO = 22/5.1 = 4.31 22/13.5 = 1.63
RX8 = 21/5.9 = 3.56 21/14.5 = 1.45

Now someone can say well the renesis's poor fuel efficiency is offset by the superior handling and braking it yields:

As for the handling part, the OBJECTIVE scores do not reflect this:
R&T Slalom (MPH) R&T Skidpad (Gs)
350Z: 65.6 .89
G35 Coupe 67.7 .92
WRX 62.8 .84
RSX-S 66.8 .82
S2000 65.9 .90
EVO 68.7 .98
RX8 65.4 .88

As for the braking the RX8 does well, but let's see how well when we take its fuel efficiency into account:

Average EPA Fuel Efficiency/60-0 Ft. Braking Distance (higher numbers are more efficient)

350Z: 23/119 = .19
G35 Coupe= 23.5/117 = .20
WRX 23.5/138 = .17
RSX-S 27.5/146 = .19
S2000 23/123 = .19
EVO = 22/117 = .19
RX8 = 21/114 = .18

The point of this is that the renesis (at least as part of the RX8) is not as efficient (in terms of fuel consumption) as its piston competitors at producing power and performance. A higher performance version will likely have to solve this lingering rotary problem OR be a very lightweight vehicle without a significant increase in displacement.

Check out mazda's site and their own internal sales guide.

OK, this is way off-topic, but this thread made me wonder... where's Buger????!!!

When you are "mag racing" you should take everything even the so call "objective test" with a grain of salt. Let's take a moment here and try to duplicate how a mag racer thinks.

R/T stats:
350Z: 65.6 .89
G35 Coupe 67.7 .92

wow, the G35c must handle much better then the 350Z.

C/D stats:
G35c 0.86 g
RX-8 0.91 g

can't find slalom from that article...but there is: "Its [RX-8] transient handling is similarly superior. [to G35c and Cobra]"

WOW! RX-8 must out handle G35c and the 350Z!. :eek:

Or all time my favorite stat:
Mclaren F1:
.86g
64.5 mph

[sarcastic]What a "crappy" handler![/sarcastic]

Unfortunately, many people actually do think like this. Now how do you reconcile R/T's .92g with C/D's .86g for the G35c? How do you reconcile the fact that R/T's stats state the G35c "handles better" than the RX-8 but C/D states otherwise?

I recommend reading up on the scientific method ;)

Whatever, I was showing that the benefits of the rotary (i.e. less weight, better balanced car) did not seem to outweigh its negatives (fuel efficiency). Yes there is variability in these figures due to a myriad of reasons (weather, driver, track, etc.), but using one source will limit that to some extent. Of course there will always be a few odd-ball figures in these handling tests, but that does not make them worthless.

They are a useful tool AS A SUPPLEMENT to subjective handling traits (i.e. steering feel, nimbleness, tossability, confidence inspiring, etc.). Unfortunately, subjective tests are not as easy to compare. Though, if you read between the lines , you will see subjective comments (or as Don would say "Damning with Faint Praise") about understeer, body roll and it being a poor autocross car (in stock form at least). So, I have yet to be convinced that the RX8 has "superior handling" compared to sports/performance cars, especially when taking fuel efficiency into account. Against most sports sedans, I would agree the handling should be better.

The central question is: does the benefits from the rotary (in this case: lighter weight and balance yielding better handling) outweigh its negatives (in this case: poor fuel efficiency)? From what I have seen it is no. Of course here we are putting equal weight on both, but I'm sure in the real world most would not put that much emphasis on fuel economy (well maybe in Europe). However, as a design (at least in the form of the RX8) it does not seem to produce as much performance as its piston competitors when fuel efficiency is considered.

Thus my main point is that if a rotary is not nearly as fuel efficient as its piston competitors, its going to have to sacrifice speed to keep the fuel economy difference from getting ridiculous (which is the case in the real world) UNLESS it is made super light (and lacks the amenities of its piston rivals). So, we are back to it being a niche engine.

So then revhappy, let us 'nichers' enjoy the car for what it is.

You have your Evo right?

This topic is WAYY off now from what I started it out to be which is simple: Would the rotary engine be more efficient (in power or efficiency) had it been given the same amount of development time as piston engines.

I think the conclusion here is that had the rotary been given as much money and effort as piston engine, we'd have a far superior engine in EVERY way to the piston engine.

Only a handful of engineers over the last 20 or 30 years have developed a 1.3L wankel that gives out more power per liter than any car on the road today. Imagine if they had millions more and more brilliant minds working on it.

Oh, one addendum though...

I fail to realize, and it has been debated thru this thread, what gas mileage has to do with inherent performance of an engine.

Are you buying a fuel miser car, or are you buying a sports car?

If you are buying any of the listed cars (350Z, G35 Coupe, etc) for fuel economy then you're buying them for an unintended (and probably poor choice) purpose. The goal of all these cars is to bring a grin on the face of the person who's driving.

I think that the low weight of the RX-8 (regardless of straight line power) will put a big grin on my face, similarly where you will love the power of the EVO. However being that I don't like AWD it was not a choice for me, and it would be the G35 Coupe that would compete for the RX-8's spot in my garage. On paper it seems the RX-8 would provide the driving experience I want in a car...

Anyways since I'm not a mod here, can we please get this topic either back on track, or split into a different one?

Cheers.

I think it would be much better than it is even in Renesis form, but in EVERY way, I am not so sure. Remember my wheel analogy- the basic design is fixed. The wankel is by nature a low-displacement, high-revving engine. This is at cross purposes with low-end torque and fuel efficiency- pretty much the only drawbacks of the engine, when you think about it!

I guess supercharging, etc could come in to play here, but in its raw form, I don't have the imagination to guess at what could make the engine more powerful or efficient.

oh, yes, you could improve on it in every way. with application specific materials (which may, or may not be as utile in piston engines) the thermal losses from the giant surface area in the combustion chambers could be reduced greatly, helping to eliminate the cooler zones in the corners and edges where unburnt fuel goes to waste and eventually gets out and pollutes.

just 'cuase the geometry is fixed doesn't mean you couldn't screw around with the proportions to make a very large displacement, low revving, high compression motor (for diesel application or something)... big big rotors, that're very skinny could maybe get the compression ratio high enough (i've never figured the math, so i'm not sure)...
but you are very right about the fuel consumption being its only drawback... whereas again, i must contest this notion of low torque: it's not low torque. it's low in comparison to a very large, long stroking engine. it's actually pretty damned amazing when you line it up against straight fours, which are (in size-limited application) more similar... smaller, but as (or more) powerful than much larger engines, with the only drawback fuel consumption??? c'mon... it's not THAT bad... it's a couple mpg short of the S2000, which is a couple of bucks per week... sweat it out if you like, but i don't and won't care: gas is the cheapest part of owning a performance car.

as for how to "improve" the engine without resorting to forced induction, it's pretty simple: you can increase the force the engine makes per turn at some speed, or increase the speed at which it can make some amount of force: more rpms, more torque = more power.
to increase the amount of force the engine can make per turn, you have to improve the amount of air + petrol it can burn per turn, in amount (filling the volume as full as possible) and efficiency (losing as little energy as possible to pumping it in and out).

Well, I still think fuel efficiency matters, even if you don't care about the gas costs. If fuel efficiency/emissions had NO impact, then I'm sure Mazda would make a larger engine (that would still be smaller than its piston counterparts) and let the thing suck gas and emit black clouds and end all of the talk about it being inferior in a straight line.

The bottom line is that fuel efficiency/emissions does matter in that it can't be ridiculous compared to the competition. Whether that is due to the individual consumer or goverment regulations, it doesn't really matter as the rotary's inefficiencies (in this regard) will put it at a competitive disadvantage. The metrics I posted clearly showed that the RX8 is inefficient (in regards to fuel consumption) at producing power and overall performance. Really, what it shows is that the car should be lighter to increase performance and improve fuel consumption.

Personally, fuel consumption IS a consideration for me, though secondary to performance. Its not due to cost, but I appreciate an efficient design and will encourage ones if I can. I think this is relevant to the discussion as it is one of the primary negatives of the rotary currently.

That being said, this engine has so much potential from a performance point of view. Really, if this problem was licked, I think the rotary would be the engine of choice for many sports cars. Maybe Mazda can hire Wakeech or Buger to work in R&D on this issue? :)

...yeah, i just rememberd you have an EVO... what're your "real world" numbers that you're getting from your (obvious ;)) spirited driving??

...oops, another thread steer'd OT by your truly... oh well... :D

Haven't got it yet. I'm on a waitlist for a garage in my apartment complex. It looks like 20-25 MPG is doable WHEN DRIVING REASONABLY based on this thread on evolutionm.net:

http://forums.evolutionm.net/showthr...g&pagenumber=1

Its really not bad when you consider its power, engine torque, weight, AWD and aggressive gearing.

Well Mazda got the emissions problem of the rotary fixed... I'm sure as the development takes its turns, then we'll see better and better numbers from the estimates.

Besides, the *best* thing about the rotary, in preparation for the future.... is its ability to combust hydrogen fuels better than piston engines.

And with the Powerball technology emerging (and others like it) for the future, you'll have a nearly unlimited supply of fuel in your car. One load of powerballs, say 5 gallons worth, will give you about 400 miles at 10mpg.

No emissions either :)

Everything comes in time. From your own words, you support the economical design when you can. I'm supporting the design that will break the mold and *be* the future. :)

You'd be surprised at the variations that can come from these test. Depending on variations in conditions, results can be quite different. Even small changes can have large effects. No, they are not worthless. By the test I can tell the Evo has better grip then an Accord. But if results are close then favorable conditions can easily put one car in front of another UNLESS they are tested at the same time. How many of those reviews are done at the same time? none (except real comparos)

JSG seems to be having no problems with steering feel, nimbleness, confidence, etc. Also, those reviews were done on PROTOTYPE CARS. In the recent Best Motoring video Gan-san states the handling on the production car has improves greatly. "Tires seem to grip better...helps its balance"

Isn't that obvious?

Oh, on our Evo8 we are getting ~18.5 mpg. Shifting~3k

Well, I think you are exaggerating just a tad there. Road and Track lists variations of what it considers as immaterial as follows:

Slalom: 1 MPH
Skidpad: .02 G
MPG: .5 MPG

http://www.s2ki.com/forums/showthrea...hreadid=103564

Now, I don't know if those are statistically derived or not. Yes, there is variation between tests, but not many things in life are perfect. Clearly, a rational person can see a trend even if the exact figures aren't 100% perfect. I challenge you to find any one magazine that shows the RX8 getting better slalom and skidpad results (same magazine for both cars). The EPA tests are fairly standarized from what I know.



Well, I guess we'll see, but I'd be surprised if the changes are monumental since they were very close to production when those tests were done.



Not too shabby when you are only 500 RPM away from maximum torque of 273 lb-ft. in an AWD, aggressively geared car that can comfortably sit four. Still, I think your brother is cheating a bit. :)

Car and Driver. RX-8 gets 0.91g while G35c gets 0.86g. Don't have slalom results but RX-8 beats it I think. Oh yeah, these test were done at the same time so....same facilities and same conditions. (unlike R/T which basically cut/paste info)

Yeah, it does kinda irk me that we will probably be getting ~same mpg but he will murdur me in a straight line. But then I just think, "Hey I can just drive his car when I feel the need for speed" :p He probably does cheat! :D

I meant between the EVO and the RX8.


Yup, I'm just saying that the rotary's fuel inefficincies put it at a competitive disadvantage. Believe me, if this problem was solved once and for all you would see a lot of rotary powered sports cars.

Duh! That's why I stated the "skidpad obviously can tell me an Evo has better grip than an Accord". Big differences are easily seen. If you read my original statement, I stated that if results are close then it would be hard to tell exactly which car is better due to varies inconsistencies. That's just one problem with these test.

Another problem is that these handling test often fail to deliver the "whole story". Case in point: Mclaren F1, .86g, 64.5 mph. The whole point is that you do not drive a spec. sheet. You drive a car, a highly complex machine that can't be described wholely by numbers. Doing that is a lot like....rating how much fun you have in bed by a woman's chest and dress size! :eek:

It really does. But I think that if the Renesis is any indication of Mazda's commitment, then we are in good hands. We'll just have to wait and see how well the RX-8 sells. Then we can continue this conversation. ;)