Why Do Rotaries Suck?

[Jez13]

Sorry, I apologise in advance for jumping in here;

But a rotary oil pump does, and a rotary water pump and a rotary fuel pump and a rotary air compressor and 50 other rotary pumps. They all measure their pumping capacity the same way, by how much they pump in one revolution (orbit if you prefer) of their pumping medium.

The fact is only one rotary pump doesn't measure it's capacity that way, the Mazda one.

Cheers

Gary

Good one gary, not one of those pumps combusts. Its not campatable. You have one medium cylcing through those pumps and 3 different mediums cycling through a rotor. What came into the rotory engine is not the same as what leaves the rotory engine. Thats because one is a pump and one is an engine. If one cycle of a rotory engine is 1/3 of a rotory rotation then only 1.3l of air is being combusted per cycle thus making it a 1.3l.

[madbung]

Oh man...the medium will effect it's efficiencey not the displacement

[Smity42]

We have domne this before, how many 2 stroke/cycle charateristics do you want?

Inlets and exhausts at the same time

Fires every rotation/orbit/cycle of each combustion face of the rotor

Inlets every rotation/orbit/cycle of each combustion face of the rotor

Exhaust every rotation/orbit/cycle of each combustion face of the rotor

Has no valves, the rotor opens and closes the inlet and exhaust ports

Oil in the petrol

There isn't one thing that the rotor does that is a unique 4 stroke characteristic.

How about each face of the rotor performing all 4 steps of the otto cycle in order? Seems to fit that pretty well.

I've never tried to call it a 4 stroke however. I have said many times, it is neither. IT IS DIFFERENT. It doesnt even have pistons!

Why not, we do it with a 2 stroke piston engine.

No we don't or we'd get double the capacity.

Even that doesn't work, because a rotor has 3 sides and a 2 stroke piston only 2. So we would have to look at 2/3rds.

Another reason why you shouldn't call a rotor a 2 stroke. ITS DIFFERENT!!!!!

Exactly, that's why we don't count crankshaft revoltions in a piston engine, but you want to count eccentric shaft revolutions in a rotary engine.

You see your problem? Every rotary argument you raise has consequences elsewhere in the package of Mazda lies. You can't be correct with 1 without killing the other 2 arguments

You have the same problem when trying to call it a 3.9L 2 stroke or the equivalent of a 7.8L 4 stroke. That physics just doesnt add up.

2 strokes, one up and one down

And how does a rotary do 2 strokes again? Oh it doesn't. It just does 1 cycle, which is EQUIVALENT, but not THE SAME as 2 strokes of a piston.

Think Otto cycle, after all it's a combustion engine. It a 4 part cycle, a 4 stroke/cycle engine does each of the 4 individually. Whereas a 2 stroke/cycle engine doesn't, it combines parts of the cycle, it does them simultaneously. Just like a rotary.

I'll give you that they all do the otto cycle. Thats pretty obvious. But face of the rotor does all 4 parts of the otto cycle. Each face of the piston in a 2 stroke DOESN'T. Oh look, another difference. In fact, thats that unique 4 stroke charactaristic again. What if I want to define them that way? That would make it a 4 stroke. Oh, I can't, thats not the definition. well, Neither can you just define it how you feel like either.

http://www.answers.com/topic/two-stroke-cycle

http://www.yourdictionary.com/two-stroke

http://www.google.com.au/search?hl=en&...on&ct=title

http://dictionary.babylon.com/two-stroke

http://encyclopedia2.thefreedictionary.com/two-stroke

http://www.allwords.com/word-two-stroke.html

http://dictionary.reverso.net/english-definition/two-stroke

A 2 stroke, BY DEFINITION, is a piston engine. Set theory again:

2 strokes are a '1 cycle' engine (if 1 cycle = piston up + down)

4 strokes are a '2 cycle' engine (if 1 cycle = piston up + down)

wankels are a '1 cycle' engine (if 1 cycle = 1 rotation of the piston)

so, wankels and 2 strokes are both SUBSETS of the SET '1 cycle' motors.

But this does not mean Wankel = 2 stroke.

Eg. 3 is an odd number. 5 is an odd number. But 3 is not the same as 5. I don't know how I can make it any simpler for you.

PLEASE STOP CALLING WANKELS A 2 STROKE You can call it a 1 cycle if you like. You can say its SIMILAR to a 2 stroke if you like.

If you can reference me ONE definition of a 2 stroke engine that doesn't refer to pistons, I'll happily revisit this argument.

On the capacity argument, I am happy to let you call it a 3.9L wankel. I think that is accurate. But that is NOT THE SAME as a 3.9L 2 stroke!!!!!!

I can also see the other side of the argument where 1.3L is derived from too. I personally think a 3.9L is more accurate, for all the reasons you have outlined. But again, that 3.9L is NOT THE SAME as a 3.9L 2 stroke

[Jez13]

Hence why it's a rotating combusion chamber, by George I think he got it.

Cheers

Gary

Yes I have got it - its not a rotating combustion chamber its a rotating rotor. The combustion chamber is in the same place and doesn't move.

[Birds]

No not realy, there are simply a few rotary huggers that won't admit to the truth no matter how many times and different ways we explain the logic consistency and factuality of it.

I actualy think quite a few have changed their mind. Maybe not on all points, but on some, most definitely.

Having gone into battle with blind rotary huggers for many years, this is not so painful at all.

I'm not a rotary hugger so what category do I fit into? I've been arguing facts, just like you claim to be, since page 1 of this thread. I neither like or dislike rotaries and I have no affiliation with Mazda...so where is my motivation coming from? I like an argument and resolution of said argument but there's no bias here...

Industry standard not good enough? how can it not be measure by it's displacement like all other pumps/engine. why is it "special" it serves the same purpose of the other products..

What does it flow? ie: what is it's displacement/swept volume it's output and it's efficiency. what else is there? what else is relative to this wankel engine/pump?

Really what other criteria did you have in mind? what else would a mechanical engineer be interested it?

It's mass and weight, yes for different reasons in the overall package...

For a fresh reference if you cbf going back searching.

* note the elliptical movement of the rotar (via the gearset) creating the 4 chambers

Yes, industry standards were not good enough. That's the problem with INVENTION. Why do new designs have to conform to old science? Why do the witchburners claim it needs to be assimilated when it is so invariably different to any other engine in existence? You really don't recognise how different this engine is...get the pistons out of your heads, you can't measure it in the same way.

And be careful pointing out the 4 chambers/states...Gary might have something to say about it being anything like a 4 stroke engine.

[GT-R32]

Here's where the rotary guys lose the battle;

You can't claim it has only one combustion chamber and at the same time it's not a 2 stroke, it inlets at the same time as it exhausts. Everybody knows that 4 strokes don't do that, only a 2 stroke does.

If you claim it has 3 combustion chambers to avoid the 2 stroke evidence, then you can't claim it is 1.3 litres

You can't claim it's a 6 stroke and then only count 1/3rd of it's combustion processes to determin capacity.

You can't use eccentric shaft degrees to determin a rotary engine's capacity and then refuse to use cranckshaft degrees to determin a 4 stroke piston engine's capaciity

When you isolate an individual lie about a rotary engine (capacity, rpm or stoke/cycle) and use specifics and narrow definitions to support that lie, you lose the other arguments. Use all of the evidence and apply all of it to the 3 questions and you end up with only one conclusion, 3.9 litre 2 stroke rotary engine where the rotors only do 3,000 rpm.

Cheers

Gary

A 4 stroke/cycle engine is classified by Otto cycle, for which the rotary engine clearly performs. This is technically undebatable.

And here's where your logic falls down as hypocritical and technically incorrect. If you consider it to be a 2 stroke, you can't consider that separate faces of the rotary-piston to be separately rated, because they perform separate parts of the 4 Otto cycles at separate times. If you wish to count faces as cycles, you will clearly note that they perform these 4-functions separately.

You either consider it to be a 2 stroke or you consider it to be a 3.9L. They contradict one another.

I was talking equivalents, using where power and torque are measured as the relative. How difficult is that for you to understand?

FACT: The 2-rotor 13B engine discussed fires air/fuel mixture 2 times per crank revolution.

FACT: This is equivalent to 2.6L 4 stroke.

FACT: This is equivalent to 1.3L 2 stroke.

FACT: This is equivalent to 3.9L 6 stroke.

[NZM.031]

i like rotors for rotors... i dont care how they work, or how efficient they are... i dont even care how much power they have.

there is nothing like a rotary.. atmo, turbo, 12a, 13b, 20b, injected, carby, pp'd, stockers, wateva.. rotors are cool.

[Sydneykid]

Good one gary, not one of those pumps combusts. Its not campatable. You have one medium cylcing through those pumps and 3 different mediums cycling through a rotor. What came into the rotory engine is not the same as what leaves the rotory engine. Thats because one is a pump and one is an engine. If one cycle of a rotory engine is 1/3 of a rotory rotation then only 1.3l of air is being combusted per cycle thus making it a 1.3l.

Please do some research, a combustion engine is by definition an air pump, it sucks air in, it compresses it and then it pumps it out.

Cheers

Gary

[Jez13]

Oh man...the medium will effect it's efficiencey not the displacement

But the displacement of an engine is measured by the combustion chamber, which is 1.3l

[Jez13]

Please do some research, a combustion engine is by definition an air pump, it sucks air in, it compresses it and then it pumps it out.

Cheers

Gary

An air pump does not self generate its power where an engine does. They are not the same thing otherwise throw an air pump by itself in a car and see how well it performs.

[Sydneykid]

I'm not a rotary hugger so what category do I fit into?

Not sure yet, I do know I prefer your never say die attitude.

I've been arguing facts, just like you claim to be, since page 1 of this thread. I neither like or dislike rotaries and I have no affiliation with Mazda...so where is my motivation coming from? I like an argument and resolution of said argument but there's no bias here...

Bias, maybe not. But I'm not convinced that you aren't a victim of Mazda's marketing spin, an innocent victim maybe.

Yes, industry standards were not good enough. That's the problem with INVENTION. Why do new designs have to conform to old science? Why do the witchburners claim it needs to be assimilated when it is so invariably different to any other engine in existence? You really don't recognise how different this engine is...get the pistons out of your heads, you can't measure it in the same way.

As you stated, it's an Otto cycle engine and so we should measure it's capacity the same as we measure every other style of Otto cycle engine. In no other Otto Cycle engine are the crankshaft revolutions used to determin it's capacity, so I fail to see any reason for making an exception by using eccentric shaft revolutions for one Otto Cycle engine only.

And be careful pointing out the 4 chambers/states...Gary might have something to say about it being anything like a 4 stroke engine.

Each one in it's turn.

Cheers

Gary

[DRD-00F]

A full rotation is a full rotation of the rotor, I cannot dispute that. But a full combustion cycle of a rotory I can debate. And then that moves to the whole last three pages of my points on where the combustion chamber is and how it is measured. With a piston its easy to determine because it happens in one spot. Well it should be easy with a rotory too because it also happens in one spot lol. But an alas from me too lol, its muddy there as well.

Yes it happens in one spot, but the medium by which it happens (the rotor face) is DIFFERENT until it comes full cirlce. This, to me, is a CYCLE. It has a beginning, and the end comes FULL CYCLE back to where it was, and starts over again. That's a cirlce, that's a cycle, that's a loop... call it what you want. Are you denying that what I just described is not the most perfect measurment of a cycle in the rotary engine? It's done 100% of what it possibly can, and started at exactly the same spot again.

It wouldn't be logical to say it's a 4 litre engine...you would instead average 1.3, 1.3 and 1.4 (well, this 1.4 is assuming that both rotors developed the exact same chip/score in the same chamber).

I lol'd at the wheel of fortune analogy. Can't we end this thread on a bit of humour like that?

Why would you average it? You don't average the airflow between twin turbos, that's stupid. You add them together. If, for some reason, like above, one chamber held more air then the rest, when you did a flow test, you would physically SEE that! What if you had one chamber that was 3L and the others were 2L? Is it a 7L engine, or a 2.333333333333L engine? If you're having to divide this and that by that and this then you haven't included all the variables (rotor faces/combustion chambers).

I tried The Price is Right first, they don't have a wheel

Yes, industry standards were not good enough. That's the problem with INVENTION. Why do new designs have to conform to old science? Why do the witchburners claim it needs to be assimilated when it is so invariably different to any other engine in existence? You really don't recognise how different this engine is...get the pistons out of your heads, you can't measure it in the same way.

Yes you can, and it's been done.

And it's not all that different. It uses the same ideals with the same intake medium, outputs the same medium, creates the same rotational force, is used in the same fashion to create the same outcome. It even does all this in the same way (otto cycle). Doesn't matter if you stand on the scales or sit on the scales, you're still going to get your weight.

If you want to talk different internal combustion engines, write an essay on the Brayton cycle.

[madbung]

I'm not a rotary hugger so what category do I fit into? I've been arguing facts, just like you claim to be, since page 1 of this thread. I neither like or dislike rotaries and I have no affiliation with Mazda...so where is my motivation coming from? I like an argument and resolution of said argument but there's no bias here...

Yes, industry standards were not good enough. That's the problem with INVENTION. Why do new designs have to conform to old science? Why do the witchburners claim it needs to be assimilated when it is so invariably different to any other engine in existence? You really don't recognise how different this engine is...get the pistons out of your heads, you can't measure it in the same way.

And be careful pointing out the 4 chambers/states...Gary might have something to say about it being anything like a 4 stroke engine.

If and it can be classified under the accepted standards, why is it treated a an individual case by it's manufacturer?

Would it be for market position (a point of difference) profit?

Because the standard measurements not only point out the wankels strengths but also it's weaknesses to the uniformed?

A pump/engine is just that, this is nothing more than a variation (wankel) of an very old design (rotary pump)

Get over it, rotary pumps have been rated this way long before the wankel and will be long after. I won't bow down before Mazda's or wankels renegade attitude and misleading information. I aint broke and it can be measured.. so why change the standard? because Mazda and Wankel say so? That's ridiculous.

It's like telling me oak trees must be measured in inches but elms are measured in cm.

It serves the same purpose, it can be measured by the accepted industry standard...so

P.S my first rotary was a 12a s1 rx7 purchased in 1986 and Gary seems to have a fair understanding of the "otto" cycle I doubt he's confused by it, neither am I.

[Jez13]

You know what gents,

I have decided to make my last post on this subject with what I think is a plausable conclusion.

If someones definition of a rotories cycle is 120 degrees of a rotor or one combustion, or if ones perception of a rotors displacement is measured by the static combustion area of a rotor housing then their answer would be 1.3ltr rotory engine

If someones definition of a rotories cycle is 360 degrees of a rotor or three combustions, or if ones perception of a rotors displacement is measured by the 3 rotational chambers of a rotor then their answer would be a 3.9l engine.

Done, shakes hands with members of the debate, tips my hat, picks up breif case and adios amigos!

[DRD-00F]

Well done Jez, that's how I saw it a while ago.

My definition is obviously the fact that a cycle incorporates 360 degrees of the rotor. Otherwise, it's not a cycle, it's 1/3rd of a cycle, requiring 2 more to get back to where it was.

[Birds]

Not sure yet, I do know I prefer your never say die attitude.

Bias, maybe not. But I'm not convinced that you aren't a victim of Mazda's marketing spin, an innocent victim maybe.

As you stated, it's an Otto cycle engine and so we should measure it's capacity the same as we measure every other style of Otto cycle engine. In no other Otto Cycle engine are the crankshaft revolutions used to determin it's capacity, so I fail to see any reason for making an exception by using eccentric shaft revolutions for one Otto Cycle engine only.

Well two minds in disagreeance reveal a higher truth than two in agreeance...if we'd just agreed that rotaries don't suck from the start then no one reading this thread would have learnt much from it. I don't argue on thin air and fumes though...I concede defeat when something objective has been put out there, but I've seen nothing of this yet from either side of the 1.3 litre / 3.9 litre debate...hence I believe displacement can be a subjective thing. I just side with the 1.3 litre measurement because it was Mazdas perogative to measure it as such and that's what it has been cemented in history as. It can be shown where they obtain this measurement from, they haven't just pulled a figure out of their ass and said something like 1.1 litres. The engine is totally different to any other engine so they're not just lying about something that is already in production under a hundred different car manufacturers. I'm not a Mazda customer so it really doesn't bother me what they class the engine as. If I raced against the things I would console in the fact these engines have been studied to derive formulas designed to make things as fair as possible for the piston powered troupe.

They are the key words mate..."the same way we measure every other style of Otto cycle engine". The rotary engine came along and defied all this because it couldn't be measured the same. Science must adapt to the rotary, not the other way around. When you have a vessel that is so different to the norm the same rules don't apply, it's a different game.

[madbung]

Good one gary, not one of those pumps combusts. Its not campatable. You have one medium cylcing through those pumps and 3 different mediums cycling through a rotor. What came into the rotory engine is not the same as what leaves the rotory engine. Thats because one is a pump and one is an engine. If one cycle of a rotory engine is 1/3 of a rotory rotation then only 1.3l of air is being combusted per cycle thus making it a 1.3l.

Oh man...the medium will effect it's efficiencey not the displacement

But the displacement of an engine is measured by the combustion chamber, which is 1.3l

Mazdas 13b chamber is quoted @ 654cc x 2

Sorry Jezz, medium aka what it pumps, whether it be air, gas or syrup makes no difference to displacement it only effects it's efficiency.

[Sydneykid]

A 4 stroke/cycle engine is classified by Otto cycle, for which the rotary engine clearly performs. This is technically undebatable.

A 2 stroke piston engine also performs the Otto cycle.

And here's where your logic falls down as hypocritical and technically incorrect. If you consider it to be a 2 stroke, you can't consider that separate faces of the rotary-piston to be separately rated, because they perform separate parts of the 4 Otto cycles at separate times. If you wish to count faces as cycles, you will clearly note that they perform these 4-functions separately.

So is it one rotor and one combusion chamber or 3 combustion chambers?

If it's one rotor and one combustion chamber then it's a 2 stroke because it does all 4 processes of the Otto cycle in one rotation (orbit if you prefer) just like a 2 stroke piston engine.

If it 3 faces then face isn't a cycle, each of the 3 faces goes through the 4 Otto cycle processes, some of them simultaneously. While one face is compressing, another face is inletting, just like a 2 stroke psiton engine. While one face is inletting another face is exhausting, just like a 2 stroke piston engine.

You either consider it to be a 2 stroke or you consider it to be a 3.9L. They contradict one another.

No they don't, to be a 3.9 litre we have to count the 3 faces of the rotor to determin the capacity. If we count the 3 faces then the 2 stroke simultaneous processing can't be ignored.

I was talking equivalents, using where power and torque are measured as the relative. How difficult is that for you to understand?

We are discussion capacity, rpm and stroke/cycle type. The problem with using power and torque is efficiency, and rotaries are very inefficient in comparison with modern piston engines.

FACT: The 2-rotor 13B engine discussed fires air/fuel mixture 2 times per crank revolution.

So what, more relevant is that it fires air/fuel mixture 6 times per revolution of its 2 rotors. Which I see you get to in the next paragraph.

FACT: This is equivalent to 2.6L 4 stroke.

Doesn't that depend on how many cylinders the 2.6 litre 4 stroke has? You realy only have 2 choices, it's either a 2 cylinder or a 6 cylinder depending on whether you claim 2 combusion chambers in a rotary or 6.

If you are assuming a 2 cylinder 2.6 litre 4 stroke, then it fires 1 time per crank revolution.

If you are assuming a 6 cylinder 2.6 litre 4 stroke, then it fires 3 times per crank revolution.

As you said 1 or 3 doesn't = 2.

FACT: This is equivalent to 1.3L 2 stroke.

Doesn't that depend on how many cylinders the 1.3 litre 2 stroke has? Once again you realy only have 2 choices, it's either a 2 cylinder or a 6 cylinder depending on whether you claim 2 combusion chambers in a rotary or 6.

If you are assuming a 2 cylinder 1.3 litre 2 stroke, then it fires 2 times per crank revolution.

If you are assuming a 6 cylinder 1.3 litre 2 stroke, then it fires 6 times per crank revolution.

Let me guess, you choose 2 cylinder 1.3 litre 2 stroke. Then you're stuck with that 2 stroke problem again.

Obviously 6 doesn't = 2

FACT: This is equivalent to 3.9L 6 stroke.

OK, you got me on this one, what's a 6 stroke? Would that be 6 combustions? In which case yes, I agree. But if you mean 1.5 times the 4 Otto cycle processes then I don't agree. Because is see no basis for 1.5 times anything.

Cheers

Gary

[Birds]

Yes it happens in one spot, but the medium by which it happens (the rotor face) is DIFFERENT until it comes full cirlce. This, to me, is a CYCLE. It has a beginning, and the end comes FULL CYCLE back to where it was, and starts over again. That's a cirlce, that's a cycle, that's a loop... call it what you want. Are you denying that what I just described is not the most perfect measurment of a cycle in the rotary engine? It's done 100% of what it possibly can, and started at exactly the same spot again.

Why would you average it? You don't average the airflow between twin turbos, that's stupid. You add them together. If, for some reason, like above, one chamber held more air then the rest, when you did a flow test, you would physically SEE that! What if you had one chamber that was 3L and the others were 2L? Is it a 7L engine, or a 2.333333333333L engine? If you're having to divide this and that by that and this then you haven't included all the variables (rotor faces/combustion chambers).

I tried The Price is Right first, they don't have a wheel

Yes you can, and it's been done.

And it's not all that different. It uses the same ideals with the same intake medium, outputs the same medium, creates the same rotational force, is used in the same fashion to create the same outcome. It even does all this in the same way (otto cycle). Doesn't matter if you stand on the scales or sit on the scales, you're still going to get your weight.

If you want to talk different internal combustion engines, write an essay on the Brayton cycle.

I say you should average it because for the other 2/3 of the time the engine isn't going to be a 7 litre and isn't going to be performing as such either. Let's hypothetically stretch out your example for the sake of explaining why we would do this. Imagine two chambers have 2L each and one chamber had a very hypothetical 200L...will this engine perform like a 204L rotary all the time? Or will the other two chambers compromise the 200L combustion chamber to produce performance more on par with an average rather than a sum...say 68 litres? That is why we would average it. You can't just sum it because not all chambers are combusting at the same time...and only an average will account for time.

Do you mean to say that the rotary has the same inputs and outputs as a piston engine? The very things that I said are the only things you can compare a piston to a rotary using? This is fascinating because I said this about 30 pages ago. The rest of the engine is different...incidentally, this includes the in betweens (supposedly the most important part of how an engine works)...the very place where displacement is derived from...and it is different.

[DRD-00F]

A 6 stroke is when on after combustion and exhaust in a 4 stroke engine, water is shot into the bore and the heat makes it steam, which makes it expand, which continues the stroke of the piston.

This also helps to dissipate heat and saves fuel.