Why Do Rotaries Suck?

[LeCoq]

not only they shit but they sound shit too! lol

[Parag0n]

not only they shit but they sound shit too! lol

An excellent contribution my dear deaf friend.

[GT-R32]

Yeah rotaries sound rubbish, all of them! Oh, wait up:

[FineLine]

Yeah rotaries sound rubbish, all of them! Oh, wait up:

Wait for what. It still sounded like shit and in the flesh would sound worse. We wont even mention the idle.

[Sydneykid]

This is prime example of selective argument, in this case where 3 points are raised (capacity, cycle and rpm) and then arguing each point individually. Whilst ignoring that the 3 points are related, and in trying to support one point you undermine the other point. I have put forward a view from the very first post and that view has not changed, that being a 13B is a 3.9 litre 2 stroke that only revs to 3,000 rpm and that Mazda lied about all 3 for marketing reasons. I have repeat that view many, many times, to remind the readers exactly what my view is and that it has not changed.

Keep in mind the 3 capacity arguments;

1.3 litre = 2 combustion chambers

2.6 litre = eccentric shaft degrees of rotation (1080 versus 760)

3.9 litre = what it pumps in a complete cycle (rotation, orbit) of the rotors.

Now let's start with capacity versus cycle;

Your classifications of four and two stroke are incorrect. Each rotor face performs the Otto cycle in four distinct sections, that's all that matters and you will find just about technical texts agree with me. It's a 4 stroke/cycle engine.

In order to claim 1.3 litres you have to support the argument that there are only 2 "combustion chambers" so 2 of the 4 Otto cycle processes occur simultaneously in the same combustion chamber. That's a 2 stroke.

By your logic a multi cylinder 4 stroke engine is 2 stroke because of where each piston is up to in the Otto cycle. LOL! It's flat out wrong Gary.

That's ridiculous, because it has more than 1 combustion chamber (cylinder if you prefer). We only count Otto cycle in one combustion chamber at a time. More importantly by making this statement you have now switched over to a rotary having 3 combustion chambers per rotor. Please make up your mind, which is it, 1 combustion chamber per rotor or 3?

What? That a stroke isn't 'wasted' because intake and compression occurs in other parts of the engine? Honestly. There are 4 distinct things happening here. It's a 4 cycle/stroke. Do some more reading and come back.

A 2 stroke piston engine does the full 4 processes of the Otto cycle, it just happens to do 2 of them at the same time. Because of this simultaneous action, a 2 stroke can do the 4 process in one cycle of the pistons. Whereas a 4 stroke takes 2 cycles.

The obvious problem with your argument is that you selectively use 1 or 3 combustion chambers to diffuse comparison with the 2 stroke cycle. It's a good tactic, but only if we ignore the capacity argument that you are trying to support at the same time. So what's you choice? You can't switch between them to suite your argument at the time, you have been but it's time to stop, make you choice and then stick to it.

So is it one combustion chamber, in which case it's a 2 stroke or is it 3 combustion chambers, in which case it's still a 2 stroke.

Relevant? Of course it's relevant. It's a FACT.

Oh give me a break, the sun rises in the east and sets in the west that a fact, but it's irrelevant to this discussion.

WTF are you on about? At least you are discussing relatives although it appears you are confused.

The 1.3L 2 stroke equivalent would be a 2 cylinder each of 654cc capacity.

The 2.6L 4 stroke equivalent would be a 4 cylinder each of 654cc capacity.

You missed it again, obviously I'm being too subtle, let's have another go.

"The 1.3L 2 stroke piston engine equivalent would be a 2 cylinder each of 654cc capacity". How many crankshaft revolutions? That would be one.

"The 2.6L 4 stroke piston engine equivalent would be a 4 cylinder each of 654cc capacity". How many crankshaft revolutions? That would be two.

What you are saying is a 1.3L rotary would be a 2 cylinder each of 654cc capacity". How many eccentric shaft revolutions? That would be one (OOOOOO look it's a 2 stroke).

Or a 3.9L rotary would be a 6 cylinder each of 654cc capacity". How many eccentric shaft revolutions? That would be one (OOOOOO look it's a 2 stroke).

There's your problem with the 4 stroke argument, if you use 2 combustion chambers you loose on simultaneous cycles and 1 revolution of the eccentric shaft. If you choose 3 combustion chambers per rotor, you loose again on simultaneous cycles and 1 revolution of the rotor.

What you are currently doing is arguing that it's a 2 combustion chamber engine to keep it at 1.3 litres, and then arguing that it's a 6 combustion chamber engine to repel the 2 stroke arguments. Make up you mind, pick one and stick to it.

I'm talking equivalents which is particularly difficult for you to understand, we end up going around in circles. I call it a 3.9L Wankel. That's the only correct way to rate the engine, which is the equivalent to the various piston engines as I have already explained dozens of times, which is in accordance to many other bodies that rate the engine... For some reason you are insistent on arguing this point?

So then it's a 3.9 litre Wankel engine and hence Mazda lie when they say it’s a 1.3 litre rotary. Or are you going to argue that “Wankel” and “rotary” aren't synonymous?

The

engine is NOT and will never be correctly classified as a 3.9L 2 stroke. You can pretend it's geared 1:1 rotor to output. But it's not. Stop trying to put it into that box.

I’m not pretending, I’m ignoring it, because its irrelevant.

Let's all say that the RX8 has the following engine to make Gary happy:

3.9L 6 chamber(/cylinder) 3,000RPM rev limited engine making peak power of 170kW @ 2733RPM and max torque of 633NM @ 1833RPM.

You left out 2 stroke for a start. And you tripled the torque, on what basis?

But you know what? That isn't true. It's NOT FACT. When the International Engine of the Year was awarded to the RENESIS for the 2.5-3L catagory it was done so with the RENESIS being rated at 2.6L.

Why? Because I think those engineers have some idea of relative.

What was their choice, “1.3 litre rotary engine of the year”? The important point here is even they admit Mazda lies when they claim 1.3 litres. And that CAMS are wrong with the 1.8 times (ie; 2.3 litres) capacity equivalency.

Cheers

Gary

[Yo-Yo]

fark this thread was at page 29 last time I checked!

I've got some reading to do

[Granthem]

fark this thread was at page 29 last time I checked!

I've got some reading to do

Farkin Same! It grew like bacteria again

[Smity42]

And you tripled the torque, on what basis?

Oh come on. Torque is proportional to Power/RPM. So if you are going to use the rotors' 3000 revs as your RPM instead of the e-shaft's 9000 revs, the torque figure is going to be 3x bigger. That is a pretty basic concept for someone who is apparently deciding how CAMS compares engines to not comprehend.

CAMS are wrong with the 1.8 times (ie; 2.3 litres) capacity equivalency.

Actually it seems pretty good to me. the theoretical 4 stroke equivalent would be 2.6L, (ie 2 times 1.3L or 0.66 times 3.9L) but the 1.8 times accounts for the inherit inefficiency of the rotory.

I also notice that you have once again ignored all my valid arguments why you should please STOP CALLING IT A 2 STROKE. That's OK, you are clearly not going to change your mind on that front, hopefully others have read them and will not blindy follow you down the close minded "its a 3.9L and a 2 stroke so we must double the capacity" path. It's SIMILAR to a 2 stroke yes, but not in the way that means you double its (3.9L) capacity

[mad082]

LOL

[GT-R32]

Wait for what. It still sounded like shit and in the flesh would sound worse. We wont even mention the idle.

Open them both at once.

Start this video at 11 seconds:

Start this video at 33 seconds:

http://www.youtube.com/watch?v=wBz9wsLT3DA

Then very slowly think about why the firing patterns give off a similar resonance. No, I'm not arguing engine note.

This is prime example of selective argument, in this case where 3 points are raised (capacity, cycle and rpm) and then arguing each point individually. Whilst ignoring that the 3 points are related, and in trying to support one point you undermine the other point. I have put forward a view from the very first post and that view has not changed, that being a 13B is a 3.9 litre 2 stroke that only revs to 3,000 rpm and that Mazda lied about all 3 for marketing reasons. I have repeat that view many, many times, to remind the readers exactly what my view is and that it has not changed.

You're not the kind of individual that changes his mind in light of new evidence. We get that. All I do is demonstrate various relatives which give the reader an understanding of the engine. You push an agenda that is technically incorrect (3.9L 2 stroke).

Keep in mind the 3 capacity arguments;

1.3 litre = 2 combustion chambers

2.6 litre = eccentric shaft degrees of rotation (1080 versus 760)

3.9 litre = what it pumps in a complete cycle (rotation, orbit) of the rotors.

Now let's start with capacity versus cycle;

In order to claim 1.3 litres you have to support the argument that there are only 2 "combustion chambers" so 2 of the 4 Otto cycle processes occur simultaneously in the same combustion chamber. That's a 2 stroke.

They are capacity/displacement RELATIVES. Something you clearly don't understand as you mix them up and then argue accordingly.

This is where you are hypocritical. You call it a 2 stroke when the engine's process is viewed as a 1.3L then call it a 3.9L? Get your hand off it.

It's a 3.9L Wankel (okay, Mazda call it a rotary) which has nothing to do with a 2 stroke. You can use relatives if done correctly using an equaliser (something you fail to understand), but you cannot call it s 2 stroke, it's not. Stop trying to put it into that box for convenience's sake.

That's ridiculous, because it has more than 1 combustion chamber (cylinder if you prefer). We only count Otto cycle in one combustion chamber at a time. More importantly by making this statement you have now switched over to a rotary having 3 combustion chambers per rotor. Please make up your mind, which is it, 1 combustion chamber per rotor or 3?

You're right. It is ridiculous to view it in that way as you discount that the other parts of the engine is doing. So don't call it a 2 stroke.

A 2 stroke piston engine does the full 4 processes of the Otto cycle, it just happens to do 2 of them at the same time. Because of this simultaneous action, a 2 stroke can do the 4 process in one cycle of the pistons. Whereas a 4 stroke takes 2 cycles.

You're mixing up terminology again. 4 stroke / 2 cycles? I think you mean 2 crank rotations or 720 degrees. Not cycles. Crank rotations. Don't mix things up it makes you look silly.

The obvious problem with your argument is that you selectively use 1 or 3 combustion chambers to diffuse comparison with the 2 stroke cycle. It's a good tactic, but only if we ignore the capacity argument that you are trying to support at the same time. So what's you choice? You can't switch between them to suite your argument at the time, you have been but it's time to stop, make you choice and then stick to it.

I'm not the one selectively applying arguments. I have the open mind and ability to speak in relatives. You on the other hand made a decision pre-thread and argue on that basis. I follow each of the 4 separate processes within this engine, each of the 4 parts happening in its own distinct section of the housing. I'll look it up for you:

http://auto.howstuffworks.com/rotary-engine4.htm (this one even has colours for you to see the separate 'strokes')

http://www.animatedengines.com/wankel.shtml

http://www.howstuffworks.com/rotary-engine.htm/printable

http://en.wikipedia.org/wiki/Wankel_engine

http://en.wikipedia.org/wiki/Pistonless_rotary_engine

See all of the above refer to it as a following the 4 stroke combustion cycle. There are many, many more but that is a very quick search. They also measure displacement correctly and note the 787B has a 7.8L displacement.

So is it one combustion chamber, in which case it's a 2 stroke or is it 3 combustion chambers, in which case it's still a 2 stroke.

What? No it's not, repeating yourself doesn't mean you are correct.

You missed it again, obviously I'm being too subtle, let's have another go.

"The 1.3L 2 stroke piston engine equivalent would be a 2 cylinder each of 654cc capacity". How many crankshaft revolutions? That would be one.

"The 2.6L 4 stroke piston engine equivalent would be a 4 cylinder each of 654cc capacity". How many crankshaft revolutions? That would be two.

What you are saying is a 1.3L rotary would be a 2 cylinder each of 654cc capacity". How many eccentric shaft revolutions? That would be one (OOOOOO look it's a 2 stroke). No that would make it equivalent to a 2 stroke of 1.3L capacity - which is very different

Or a 3.9L rotary would be a 6 cylinder each of 654cc capacity". How many eccentric shaft revolutions? That would be one (OOOOOO look it's a 2 stroke). INCORRECT - IT'S THREE REVOLUTIONS.

You're not being subtle. Cute for you to act as if you are that clever. But now, you're just wrong again. See above.

There's your problem with the 4 stroke argument, if you use 2 combustion chambers you loose on simultaneous cycles and 1 revolution of the eccentric shaft. If you choose 3 combustion chambers per rotor, you loose again on simultaneous cycles and 1 revolution of the rotor.

What you are currently doing is arguing that it's a 2 combustion chamber engine to keep it at 1.3 litres, and then arguing that it's a 6 combustion chamber engine to repel the 2 stroke arguments. Make up you mind, pick one and stick to it.

Same applies to you mate. You can't call it a 2 stroke on the basis of how it works when counted as 1.3L. I can discuss relatives, you can't as you ignore it because you think it's irrelevant.

[GT-R32]

So then it's a 3.9 litre Wankel engine and hence Mazda lie when they say it’s a 1.3 litre rotary. Or are you going to argue that “Wankel” and “rotary” aren't synonymous?

They aren't. Mazda call it a 1.3L rotary. They don't use the term Wankel. I call the 13B a 3.9L Wankel and count all of the engine as you do when you compression test them. But I am capable of discussion of relatives I don't just 'ignore it'.

The I’m not pretending, I’m ignoring it, because its irrelevant.

You ignore it. Right. I am starting to realise you don't understand some concepts so I accept that. You just do a good job of arguing endlessly and pretending you know all - even dropping credibility indicators LOL. See the next point.

You left out 2 stroke for a start. And you tripled the torque, on what basis?

What, so now you don't understand how torque works? You're starting to demonstrate your limitations here Gary. Humour me on why you think I tripled it. Or perhaps have a quiet think of what a different diff ratio does to a car and get back to me.

What was their choice, “1.3 litre rotary engine of the year”? The important point here is even they admit Mazda lies when they claim 1.3 litres. And that CAMS are wrong with the 1.8 times (ie; 2.3 litres) capacity equivalency.

Cheers

Gary

No, the RENESIS won the 2.5 - 3L catagory. No matter how often you change what I said you cannot change that fact.

Oh come on. Torque is proportional to Power/RPM. So if you are going to use the rotors' 3000 revs as your RPM instead of the e-shaft's 9000 revs, the torque figure is going to be 3x bigger. That is a pretty basic concept for someone who is apparently deciding how CAMS compares engines to not comprehend.

Actually it seems pretty good to me. the theoretical 4 stroke equivalent would be 2.6L, (ie 2 times 1.3L or 0.66 times 3.9L) but the 1.8 times accounts for the inherit inefficiency of the rotory.

I also notice that you have once again ignored all my valid arguments why you should please STOP CALLING IT A 2 STROKE. That's OK, you are clearly not going to change your mind on that front, hopefully others have read them and will not blindy follow you down the close minded "its a 3.9L and a 2 stroke so we must double the capacity" path. It's SIMILAR to a 2 stroke yes, but not in the way that means you double its (3.9L) capacity

It's quite clear he is limited in some areas mate. I mean the mistakes are he thinks double 3.9L is 6.8L, thinks it fires 3.9L worth of air/fuel for each shaft revolution, accordingly calls it a 2 stroke and finally, doesn't understand the concept of torque (something doesn't have to move for it to be measured, mind).

It's becoming quite clear that spatial thinking is not Gary's specialty. It's just covered up with a very black and white attitude that gives some readers the impression he is correct as he is so sure of himself. Also riding a well deserved reputation of credibility on SAU, which are on areas unrelated and of different understanding.

I see another possibility. For instance, when GM was threatened by Japanese car makers, it responded in the 1980s by clinging even harder to its own ideals and beliefs that had 'worked' in the past. Certain individuals, when counter and further information is presented behave in much the same way, they tightly hold onto preconceived ideas, pushing them even harder, no matter their value or worth, in the face of new and further evidence or change. This becomes a reflection of the individual's or group's self concept. Given the subject of credibility has appeared so often I get the feeling this may apply.

[jase-r34]

It's quite clear he is limited in some areas mate. I mean the mistakes are he thinks double 3.9L is 6.8L, thinks it fires 3.9L worth of air/fuel for each shaft revolution

Firstly, I think you both are making very valid points and backing them up accordingly, but this kinda stuff irritates me a little...

You do realise the 6 & 7 are right next to each other on the keyboard and that 6.8 was quite possibly meant to say 7.8?

And from the reading I have done I don't think Gary says he thinks the rotary fires 3.9L of air for each shaft revolution, but for each rotor revolution (counting both rotors).

You make some great points and I enjoy reading posts from both side of the argument, but to me these kinds of remarks cheapen the rest of your post.

Just my opinion.

[nosajguy]

Who here when they first found out exactly how a rotary worked did not think to themselves: f**k. That's clever.

I took a look under the hood of my mate's S1 RX7 the other day and realized for the first time just how small they are too! I knew they were small, but this thing took up less than half the engine bay. It was all intercooler (V mount) and body kit up front. Yet this thing still makes over 250rwkw with minor modifications and a conservative boost.

So, reliability and fuel efficiency aside, why aren't there more rotor engines?

I understand the yanks love their big engines, but I'm sure they'll jump on board with a BIG (6-8?) rotor NA engine. I don't know anything about the engines beyond the most basic explanation, but surely if they can make the little 1.3L tri-rotor fit in half the hood of a tiny RX7, surely a Mustang with an engine bay twice the size could house an engine 2-3x as long.

What about AWD. Why hasn't Mazda created a crazy lightweight AWD rotor to compete with the GTR, Evo and STi?

Is it just... a lack of popularity? Technology? What's holding the ol' Wankel engine from really competing?

yeah the prety cool aii and their australian as well i think any way i want a wankle shaft motor in mine

[GT-R32]

Firstly, I think you both are making very valid points and backing them up accordingly, but this kinda stuff irritates me a little...

You do realise the 6 & 7 are right next to each other on the keyboard and that 6.8 was quite possibly meant to say 7.8?

And from the reading I have done I don't think Gary says he thinks the rotary fires 3.9L of air for each shaft revolution, but for each rotor revolution (counting both rotors).

You make some great points and I enjoy reading posts from both side of the argument, but to me these kinds of remarks cheapen the rest of your post.

Just my opinion.

Points taken. However they are related to my spatial thinking comment. Gary did admit his doubling was incorrect and it was a mistake (not a typo). I can accept that. I can accept his mistakes with regard to the 3.9L per shaft revolution too (see his post above) - as long as he can.

I just get frustrated as everything really needs to be kept in perspective with this engine and measured in both relatives and absolutes, but spoken in technical truth. Otherwise it becomes a distortion of fact - arguably just as Mazda have done by calling their engine a '1.3L Rotary' - then it becomes a pot, kettle, black scenario for those calling the 13B a 3.9L 2 stroke. A bit like Michael Moore's films actually, LOL.

[some_cs_student]

Sorry to ask a really stupid question, I've read the discussion and its interesting, one thing I'm getting confused on is the definition of capacity.

I always thought capacity was based on physical size, like the capacity of a cubed container of a certain size might be say 30L.

In terms of engines, whether its 2 stroke or 4 stroke, do we measure them both by the physical capacity? And is that measured by the size of all the cylinders combined? Or something else...just send me a link to read

Thanks

P.S. I purposely did not ask about rotary / wankel because I'm not interested in starting another page of debate...

[GT-R32]

Sorry to ask a really stupid question, I've read the discussion and its interesting, one thing I'm getting confused on is the definition of capacity.

I always thought capacity was based on physical size, like the capacity of a cubed container of a certain size might be say 30L.

In terms of engines, whether its 2 stroke or 4 stroke, do we measure them both by the physical capacity? And is that measured by the size of all the cylinders combined? Or something else...just send me a link to read

Thanks

P.S. I purposely did not ask about rotary / wankel because I'm not interested in starting another page of debate...

This is a good link:

http://www.answers.com/topic/engine-displacement

All cylinders swept volume, BDC to TDC.

[Jez13]

So I suppose my 2.5L engine should change what it is advertised as depending on what point the pistons are at? Well if that's the case, it will NEVER be 2.5L

Total displacement doesn't assume anything. It's how much air moves through the engine in total. That's what total means.

Again, not assuming anything. If an engine moves 4L of air, then it's a 4L engine. Why would i have to state if one chamber had different displacement? What if I didn't know, WHAT IF I JUST WANTED TO ASSUME MY CUSTOMERS ALREADY KNEW THIS??? I though that's what you were all about... assumptions. I still honestly believe your idea of a 'cycle' is inherrently flawed. A cycle can involve a smaller cycle, but for a true cycle, it should not differ from the previous, or the next cycle, which yours does. My cycle incorporates your 3 cycles that you mentioned. So while I've done one cycle, and could do a billion more that are EXACTLY THE SAME, you've done 3, all of which are different. That's hardly a cycle.

For simplicities sake, I was focussing on one chamber. As long as it has one, it could have 5 more and make little to no difference. Again, just talking about a single chamber... stay with me.

And to be honest, these are pretty simple machines. Whatever screen you're looking at RIGHT NOW is a much more complicated machine then these engines.

Just to clarify that a cycle does not mean a circle. It means a process of when a system of any sort completes. Like downstairs in my warehouse we have a manufacturing cycle and it looks like this (simplified):

A. Extract Parts > B. Assemble Parts > C. Pack Parts in box

This is a very simple cycle but you notice that process C does not go back to A, the process or cycle just starts again from scratch. Now lets say that there are three people at each sector (A, B and C), when 3 boxes are complete and are in a pile at the end the warehouse has officially completed 3 manufacturing cycles. Not 1.

[DRD-00F]

Right.

But MY point is that that entire process is also 1 cycle. Just 1. Instead of 3 different ones, it's just one big one.

[Jez13]

Right.

But MY point is that that entire process is also 1 cycle. Just 1. Instead of 3 different ones, it's just one big one.

Yes but what if a customer only wanted one box? Does that make it 1/3 of a warehouse cycle?

[DRD-00F]

In my definition yes.

In yours, it's just one of the 3 cycles.

one of three

1 of 3

1/3

lol

we're both right you know, just 2 different ways to look at it.