Why Do Rotaries Suck?

[GT-R32]

Or you can compare Mazda's current rotary offering, the RX8, to "Datsun's"* current GTR, which is currently dominating all motorsport at the production level.

*Somehow that word is supposed to be disrespectful, maybe we should call Mazda the "Toyo Kogyo" which produced wonderful things like the Mazdago as Japan industrialised.

Anyhow, we agree given your final statement. Finally we got there, LOL.

[RotarySnail]

Uh your leaving out a little detail in that time of WP. Street legal.

[GT-R32]

Uh your leaving out a little detail in that time of WP. Street legal.

Nothing modified in that way for that year model is street legal, especially with an after market ECU, unless emissions tested and signatory engineer approved.

[RotarySnail]

That wouldn't be a push, rice is an engineer.

[GT-R32]

That wouldn't be a push, rice is an engineer.

According to his site, he has a diploma. Even a PhD doesn't mean you are a signatory. So that's irrelevant.

Groupies shouldn't fight battles for their stars.

[RotarySnail]

I'm not going just off what his site says. If you have ever read anything written by the guy, or have a look at his buildup, you can see he knows what he is on about.

[R34GTFOUR]

This thread DELIVERS!!

[DRD-00F]

This thread DID deliver, but it's gone off its course in the last page or so, which is a real shame cause it was one of THE most informative pages I've ever read on SAU!

If some of you are done backing up the racing history of the rotary engine, which has nothing to do with the original question, then I would just like to say that with my extremely limited knowledge on the subject (rotors have always been a black magic to me, even though they peak my interest and the Series 7 RX7 gives every man wood) that I would have to agree with Gary. In my mind, I compare the face of each side of the rotor to that of the head of the piston.

In one rotation of that rotars side, it's done intake, compression, ignition, exhaust. While it's done in a different way, that is still a 2 stroke, although perhaps a better terminology for this instance would be '2 cycle'. Which again is an amalgamation in trying to convey it to an piston engine, REALLY, it would be called a '1 cycle', but then, what rotary wouldn't be a 1 cycle? So while I do agree with Gary that it can technically be looked at as a 2 stroke, how would a rotary engine be anything but?

On the capacity though, I do agree, and find myself again, comparing the faces of the rotor to the head of a piston. It's sort of like a 3 piston engine, in that by the time the first ignition is done and over with, another 2 have happened in the time it takes the first face of the rotor to get back to the ignition 'chamber'.

I'm far and beyond someone you should be listening to about rotary engines though, I don't hide the fact that I know pretty much nothing about them... All I can do is put up my view on what's being said and hope that I'm not too wrong

Oh yeah, and RPM, I dunno, it's a bit beyond what my brain can tackle just yet...

[JAS-25T]

Most of my information comes straight from the horse's mouth. I respect the man, his knowledge and his skill. I don't like the disrespect.

He has built a very nice thing himself, certainly something to be proud. People will ignore that, bash it and resent him for his words if he carries on. And from what I can see it only runs 1.08s at WP, thus far:

http://ausrotary.com/viewtopic.php?f=21&t=91985

A somewhat meagre challenge for a decent drive and a mild GTR. A much quicker car is a black bridge port RX7 from SA, which runs quick times and has 350rwkw.

Also what is a life long dedication for some men, is but a minor hobby for others. Keep it in perspective.

I've seen that lap.........One out lap, one @ 1:08 lap then one in lap.

Very, Very impressive.

[GT-R32]

I've seen that lap.........One out lap, one @ 1:08 lap then one in lap.

Very, Very impressive.

Sure is. I can say with confidence it'll improve on that by seconds next time it's out.

He has driven around Wakefield Park over the years more than most of us have changed underwear! These are in the 7s:

[JAS-25T]

We digress, but the video I saw of the 1:08, if I'm not mistaken, was of his first time out there?

surely he can answer that?

Either way, from that video, it's quite clear that it wasn't a smooth lap either with many seconds to improve just in a smoother lap, as you'd expect with a one hot lap experience.

[ylwgtr2]

did someone let the ausrotary boys in here ?

[GT-R32]

We digress, but the video I saw of the 1:08, if I'm not mistaken, was of his first time out there?

surely he can answer that?

Either way, from that video, it's quite clear that it wasn't a smooth lap either with many seconds to improve just in a smoother lap, as you'd expect with a one hot lap experience.

No he'd been out there many times prior in his previous RX7. The article of it in Zoom magazine, the pictures were taken there!

Smooth? There is no smooth in this case. There is driving by feel all the way around the track on the limit the whole time, with this style of fast.

[Streeter]

Finally the ONLY TRUE way to look at a Wankel Rotary is to view it in its own cycle! (and not comparing it to something that it is NOT!) this is only over 1080 degree's of crank shaft rotation, where ALL of the working faces can be accounted for (just as when you do a compression test to see if the poor little donk is healthy or not) For it is only when the entire engine has complete one full cycle of work can it thus be rated, be that as functional or in its true capacity sense. You will then see that the humble 13B is indeed 654cc x 3 working faces x number of rotors ! = 3924cc.

Equivalence capacity to time scale (revolutions) for 13B engine, has one power pulse per 360 degree's per rotor

1308cc 360degree's (2 stroke)

2616cc 720 degree's (4 stroke)

3924cc 1080 degree's (Wankel Rotary)

I think everyone understands this, the difference in opinion is if you count combustion FACES as displacement. Mazda didnt and the rotary has been recognised as a 1.3 litre for many years. Its the swept volume of a combustion chamber, which is one side as only one side of a rotor makes up the combustion chamber at one time.

One complete 'cycle' should be one side of the rotor, not all three. AND The engine is the rotor housing, not the rotor itself. <- this is what we are knit picking about and it comes down to your interpretation of terminology.

Sydney kid says its misleading and lying. I agree its a little misleading but I think you are going too far to say its lying about capacity.

[ylwgtr2]

[ylwgtr2]

may i be the first in this thread to declare.......

[Birds]

*warning, epicly large and informative/boring post*

OK so you agree with me that the rotors only do 3,000 cpm. Let's leave it at that and carry on.

So you agree that a 13B pumps 3.9 litres in one complete cycle of it's rotors.

Now would you like to go back and check the 2 litre 4 cylinder 4 stroke engine pumping 2 litres for every rotation of its crankshaft? It actually pumps 1 litre, it takes 2 revolutions of the crank to pump 2 litres. So using your logic of eccentric shaft revolutions somehow making a difference to an engine's capacity, then a 2 litre piston engine should really be rated as 1 litre. Now I don't know about you, but I don't do that for a piston engine so why should you expect anyone to do it for a rotary engine.

The lies started when Mazda convinced the Japanese registration authorities to only measure one side of the rotor. This resulted in two things, firstly cheaper registration because rego in Japan was based on engine capacity. Secondly it was marketing trick, small engine lots of power. Once the lies started they couldn't stop and so they spread to motorsport, which is where I have the most problem.

You believed the lies, that's OK you were only 8.

Back to your point, it's only unfair when a supposed 1.3 litre rotary engine is compared to 1.3 litre piston engine. That's where Mazdas marketing was aimed at, that's where their motorsport homologation was targeted. And it's all based on untruth, even using Mazdas "formula" it should be 2.6 litres. Using any logic of an air pump, which after all is what an engine is, it's a 3.9 litre.

You are confusing the meaning of "stroke" (up and down) in relation to an engines "cycle", it is quite common to replace the term "2 stroke engine" with "2 cycle engine". You are doing exactly what you accuse me of, trying to compare a piston engine with a rotary. Don't do it, think of it as a rotary engine, forget pistons and up and down. Now if you still have a problem with the term "stroke" being applied to a rotary then substitute it with "cycle". So back to the question, is a rotary a 2 cycle engine? The answer is yes it is, absolutely.

I'm sorry I don't understand, piston engines have crankshafts, rotaries have eccentric shafts so there is nothing common there. Why are you trying to make something that is inherently different somehow the same when the fact is they aren't.

Cheers

Gary

Agreed and agree. Given the original question was about engine RPM and not rotary cycle speed (if you look at page 1 you will see the context within which this question was put forward), all I've ever maintained is that the eccentric shaft is the part that is spinning at 9000RPM. Given that the eccentric shaft is the last static part of the engine and also the final source of engine output before the dynamic components begin, e.g. gearbox...it is this part that engine RPM in a rotary should be derived from. I am happy to leave it at that, yes.

Oops...my mistake...I'll concede that a 2 litre 4 stroke does indeed pump 1 litre of air per revolution of crankshaft...I apologise...this stuff gets to my head after a while. But therein lies our formula for working out the rotary engine's displacement advantage over the 4 stroke...it's about twice as much...i.e. 2.6 litres. And this is the ONLY REASON why the rotary is considered to be LIKE a 2 stroke piston engine when comparing it to a 4 stroke piston engine. Only because 2 stroke engines push twice as much air per crankshaft revolution as a 4 stroke. Motorsport homologation acknowledges this and the ratio used to place rotaries into displacement classes with 4 strokes is often around 2:1 (1.7:1 here in our local categories thanks to some other variables included IIRC).

I wasn't told any lies from Mazda when I was 8. As I said before, when I was 8 I knew that a rotary engine's 1.3 litres was not the same 1.3 litres as a 4 stroke piston engine. I remember asking my father why the RX7 was so much more expensive and faster than the MX5 which appeared to have a "bigger engine"...just like any inquisitive mind who actually gave a shit that the RX7 had only 1.3 litres would have done. The difference is, Mazda didn't just write it down as a 1.3 litre engine trying to pass it off as some sort of ultra powerful 4 stroke. They stated in my brochures it was a 1.3 litre rotary...and without devoting 4 pages of the brochure towards explaining how a rotary works, can we blame them. Besides, like I said before, the rotary engine has it's own rules...given Mazda is the only manufacturer who can be bothered commissioning the thing and continuing to use it, they can say whatever they want about it. I'm sure they enjoyed the same luxury being able to "lie" about their Miller-cycle engines too. Even if they do "lie" the engine will eventually be revealed for what it's truly capable of once someone test drives the thing. Even in motorsport, it will be slotted into a neat little category that homlogation officials believe it fits into...well this has been done...all around the world. End of story...lies, if they do exist, are irrelevant now.

Nah that's not true Gary. I'm not comparing a piston engine to a rotary engine. My point all along has been not to! Their combustion cycles occur in completely different ways. I would never use the term stroke to describe the combustion cycle in a rotary engine...that's your perogative. Did you read my point? Don't go calling a rotary engine a 2 stroke because it's not a piston engine. The term stroke itself is derived from the motion of a piston in a piston engine...it's why when we calculate displacement in a piston engine we measure the distance the piston travels and the surface area of it. And a 2 stroke piston engine is called so because it has a combustion stroke every 2 piston strokes, whilst a 4 stroke has combustion stroke every 4 piston strokes. Do not go using stroke to aid description of the combustion cycle in anything but a piston powered engine. Rotary engine = eliptical moving triangle shaped thing AKA rotor. It does not stroke! Now that we're finished with stroke, don't replace this word with the word cycle. Cycle is completely different to stroke. Cycle suggests a completed combustion cycle...stroke is just a single movement of the piston and there happens to be 4 of these in a 4 stroke engine! There happens to be none of these in a rotary! Plus the combustion cycle is completely different. So once again, you're basing your measurement of a rotary engine on the science of a piston engine. It's a pointless comparison because by nature this comparison favours a piston engine! Thank you to my loyal readers who have gotten this far and still know what I'm talking about.

Now you're still not getting past the idea that the eccentric shaft is the rotary engine's crankshaft. The very point of the eccentric shaft gear ratio is to bring the rotary engine closer to the piston engine by giving it a similar output speed. Thereby making it useful in a road going application, i.e. a car. You remove the rotary engine from a car and the eccentric shaft goes with it. It is a very valid part of the engine and its gear ratio is just as important as the lobes on a crankshaft which give a conrod the necessary leverage to turn a crankshaft. If it didn't have this eccentric shaft ratio it would be a useless engine that would only rev to 3000rpm with an absolute truckload of torque. Now that we know the eccentric shaft and crankshaft give rotary and piston engines something in common, any comparison between the two engines needs to be based on this. Power/torque...based on a turn of the eccentric shaft vs. a turn of the crankshaft. Engine displacement...based on a turn of the eccentric shaft vs. a turn of the crankshaft.

YES A ROTOR'S FULL COMBUSTION CYCLE IS COMPLETED AFTER 3 TURNS OF THE ECCENTRIC SHAFT...BUT THAT DOES NOT MAKE IT EQUIVALENT TO A 3.9 LITRE 4 STROKE ENGINE...BECAUSE IF WE ASSUME THE SAME GEARBOX/DIFF/TYRES FOR TWO CARS, ONE ROTARY POWERED AND ONE PISTON POWERED...WITH THESE 3 TURNS OF THE ECCENTRIC SHAFT THE ROTARY POWERED CAR WILL TRAVEL 50% MORE DISTANCE THAN THE PISTON POWERED CAR AFTER ITS 2 CRANKSHAFT TURNS (FULL COMBUSTION CYCLE IN A 4 STROKE). INCIDENTALLY THIS IS THE SAME 50% THAT YOU ENJOY ADDING TO THE PROPER 2.6 LITRE EQUIVALENCE TO GET YOUR SUPPOSED 3.9 LITRE ENGINE. Sorry for the caps and bold but this is the most important point of all. End of story.

Haha nicely done Rice. Was reading these tools going on and wondering when someone would say something with actual knowledge behind it, rather than what wikipedia brought up when rotary was typed in the search engine. How many of you children have ever worked on a rotor, or experienced one?

He's laid down the challenge, so why are all you RB-frothers still moaning? Why don't one of you go show everyone how much rotaries suck. Or is there abit of an issue doing that because your all keyboard warriors who's cars have nothing all that interesting going on?

As for rice and circuit racing. His entire build up of his current car is very well documented and the entire car has been developed himself. How many of you can boast that?

If it ain't a rotor, it's probably some skyline-blower talking trash.

Just so we keep things clear and not enter a debate over it, I'm fairly indifferent to rotaries...I don't hate them and I don't like them. But can you bugger off back to your spot lodged deep inside RICE RACING's colon? It seems to me you only joined these forums to spark some sort of RB vs rotary debate...god knows where this came from anyway...because this thread has for most part been an informative debate about the workings of a rotary engine and a physics based comparison with the workings of a piston engine...until you came along. Making some poor assumption that everyone here, up until RICE posted, has no idea what they are talking about and googled or wikied their sources of information...just...please die. Also, calling us children? Most people here legally drive and own cars...I therefore challenge you to find someone who is legally considered a child and regularly posts on these forums. Even sydneykid with his ultra deceptive name is far from a child. Who decided to post a link to this thread on a rotary fan forum with some members who clearly have nothing better to do than forum hop and bible bash their support for rotaries? If nothing else we have a nice pictorial diagram of the Wankel cycle, and for that I thank you RICE RACING.

[RICE RACING]

No worries glad to help.

[ido09s]

Superlap 2009 Results

Pro Class Winner – Tilton Interiors Evo 9 - 1:12.10

Open Class - 2nd – Bilstein Racing RX-7 – Driven By Ryan Brown - 1:15.83

Not a bad effort from a no torque, apparently shitty NA 13B is it! Cant be half as bad as most of you guys on here make them out to be. Imagine it was turbo charged like the fastest car at Superlap

[camspeed]

Nice to see a civil, mature discussion here, although you would have to say a lot has to do with personal opinions. Not denying any of the facts put forward, but we all have our passions and no matter how flawed they may or may not be, at the end of the day logic and facts can't really override a passion for something.

Many of you said you hate the sound a rotor makes, to me, there is no sweeter song than a rotor at full noise. An RB on the other hand, I can't stand it. Personal opinion.

Also RICE's car is a fair bit different now to when it ran that lap, personally I can't wait to see the results of all of his hard work on the track.