Why Do Rotaries Suck?

[GT-R32]

maybe I just like a good debate too much? And it is a very interesting topic

You clearly have a good idea of how the Wankel operates and the ability to relate it to its piston cousins, with no agenda or hang-ups about it (a critical point). But sometimes no matter how the evidence is laid out to someone, they cannot, or do not have the ability to, accept it.

The greatest loss of all is the misinformation spreading.

[SimonR32]

There are 10 tests, a rotary is like a 2 stroke in 3 of those tests

3

8

9

But it's only like a 4 stroke in 2 tests.

3

10

To me that means it is most like a 2 stroke.

Cheers

Gary

Edited for my bad maths.

YYYYYYYYYYYYESSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS!!!

So Gary has now stated that it is not a 2 stroke and not a 4 stroke... But more like a 2 stroke, which means its neither...

You can have a apple and a orange, the you can have a pear. The pear is more like a apple than a orange, BUT ITS NOT A APPLE ITS A PEAR!!!

[SimonR32]

You clearly have a good idea of how the Wankel operates and the ability to relate it to its piston cousins, with no agenda or hang-ups about it (a critical point). But sometimes no matter how the evidence is laid out to someone, they cannot, or do not have the ability to, accept it.

The greatest loss of all is the misinformation spreading.

Quoted for truth!!! I also am objective in this topic... as for the rotary engine, i don't love them, don't hate them but I respect them for what they are...

[Birds]

But they don't put them into fair displacement categories. A 13B should be included with 7.8 litre 4 stroke engines, that's 3.9 litres of pumping capacity times 2, because it's not a 4 stroke.

This is also where the turbo sizing question becomes interesting, and supports the 7.8 litre capacity equivalence. If it wasn't 7.8 litres how could it spin a T04Z using only 3,000 rpm? What the alternative, 1.3 litres? We all know that there is no way a 1.3 litre engine is going to spin a T04Z at any rpm, let alone at 3,000 rpm.

It's quite simple, an engine is an air pump and we all know how much air a rotary pumps and it sure as hell ain't 1.3 litres.

My experience is exactly the opposite, ask the average Joe how big the engine in his car is and there is a good chance he will tell you straight away. Some will look at the badge on their car. In comparison ask the average Joe the power and torque outputs of his engine and he look at you blankly. Capacity is relevant to rego, insurance, road tax, for expense claims purposes the Tax Office even quotes costs to run a car by its engine capacity. Nobody outside the enthusiast uses horsepower and torque, it's all about capacity. Ask a pushrod lover what's different about an LS1 compared to an LS2, you can bet the first response you get is 5.7 versus 6.0 litres. I don't know about you but I haven't ever seen torque output badges on cars.

I've been playing with rotary engines for a lot of years and I know full well that Mazda’s claim (for a 13B) of 1.3 litres, 4 stroke and 9,000 rpm is rubbish. The real world results don't support it, then when we get down and dirty with the facts we find they don't support it either.

1. does it ingest air like a 1.3 litre? No it doesn't

2. does it use fuel like a 1.3 litre? No it doesn't

3. does it spin up large turbos like a 1.3 litre? No it doesn't.

That’s where I started in my quest for the truth many years ago. The real world logic just didn’t stack up, not even close, so I went searching for the facts. I completely ignored Mazdas words, actions, drawings, diagrams, visual representations etc, because they would obviously be slanted towards supporting their version. I sought out independent views, unbiased opinions, reasoned measurement and unconstrained opinion. That’s why I found Phil Irving’s published engineering papers so significant. Even more so the unbelievable lengths Mazda went to to lampoon someone who was an internal combustion engine luminary. Having done that research and my own measurements, I’m left with the conclusion that Mazda has at the very least distorted the facts for marketing reasons or at the very worst lied through their teeth.

Cheers

Gary

You're looking at the 1.3 litres in a rotary as a 4 stroke engine. You can't do that Gary. I agree, a 1.3 litre 4 stroke piston engine is not going to power a T04Z well at all, especially not at 3000rpm. It's a lucky thing a 1.3 litre rotary isn't a 4 stroke piston engine. And again, rotors don't "revolve"...they have a completely different motion to pistons and the engine is so different in design that I have no idea why you are comparing it to a 4 stroke's ability to spin up a turbo? The rotary uses it's 1.3 litres worth of displacement very differently to a piston engine.

Your experience is twisting things a bit. The average joe who states his engine's displacement does so because the general assumption made by the uneducated is that the larger the engine the more power it makes and the faster the car goes. They don't actually care about the displacement of the engine. This is why you have something of a bogan following centred around nothing being faster than a big V8. It's why at the other end of the scale you have ads saying "with it's economical 1.5 litre engine blah blah". Many manufacturers take advantage of this assumption and that is the sole reasoning behind displacement badges on cars...afterall, there was a time when this assumption had truth to it. But now that forced induction and diesel engines are becoming more commonplace, manufacturers are heading towards emphasising power figures and fuel economy (though HSV and FPV have been doing this for years with their vehicle badging) rather than displacement. We even have torque figures in print because people don't like how "underpowered" diesel engines appear to be. It's no good selling a performance car to a customer with a 6 litre V8 if the thing only puts out 150kw. Do you think the customer will still be bragging about his 6 litres worth of engine? The relevance of the vehicle for the customer is how fast it goes (in the performance market) and what it costs to run the thing. Mazda's supposed 1.3 litre "lie" can't go any further than these variables. If people want to assume it's a 1.3 litre 4 stroke that's their loss. But with every 1.3 litre reference to the engine you will also find a reference to it being a rotary.

Now, RE: Mazda's supposed lying. Here's a question that I've taken the courtesy of answering for you...

1. Does a 2 stroke 1.3 litre ingest/use air/fuel and spin up turbos like a 1.3 litre 4 stroke? I'm leaving rotaries out of it for now...just look at piston engines.

No. Because in the time the 4 stroke completes its 1.3 litres, the 2 stroke has pushed out 2.6 litres. In the time the 2 stroke has moved 1.3 litres the 4 stroke has only done 650cc. Funnily enough, we still call both of these engines 1.3 litre, because they have different combustion cycles and we state as such on branding when we refer to them as a 2 stroke or a 4 stroke. Now if we look at rotary engines...Mazda refer to their engine as a rotary. Calling a 13B a 1.3 ROTARY is NO different to a manufacturer advertising a 2 stroke as 250cc on the showroom floor with a 4 stroke 250cc engine...plenty of the public won't understand that this 250cc is different to a 4 stroke 250cc, but we write on the model 250cc 2 stroke for those who do understand it...and the information is there for them. Now this is different from Mazda advertising their engine a 1.3 rotary...how exactly? Are all the 2 stroke manufacturers lying too? Your "lies" seem to be based around going out to buy a vehicle and being trapped inside a 4 stroke mindset, ignoring the fact that other engines exist and have their own ways of measuring displacement. People who know how a rotary works know that the rotor has 3 combustion sides and that the 1.3 litre capacity is different to a 4 stroke's 1.3 litres. Mazda weren't lying. I don't doubt they would have emphasised their engine being a 1.3 litre engine...this is no different to what any other manufacturer does with the marketing crap they churn out about their cars. But it sure wasn't a lie...they did NOT push for it to be viewed as a 1.3 litre 4 stroke engine...it's quite hard to get away with this when you call it a 1.3 litre ROTARY. The problem with something of genius is the narrow minded witch burners who want to apply old religion to new science...

I am enjoying this... it is like Gary is giving a bunch of apes a hammer and watching them slowly figure out what it does.

Do you have anything information-wise to contribute to the discussion or are you just trying to hook up with Gary? That's twice now I've seen you suck his dick in this thread without actually adding anything to support his case. It's starting to get annoying. From our point of view it's giving an ape a hammer and him not getting past the fact it isn't a screwdriver.

I'm sorry Gary but I'm just seeing too much fallacy in your argument...you change terms and context to suit your point of view. I'm hard pressed to say you don't have some sort of vested interest in this argument...I'd say it has alot to do with the fact you've held thse beliefs for so long, whereas the people arguing against you are flexible in their knowledge and willing to accept the alternative should it exist. You can say you were open minded and ignored everything Mazda gave the public to work with...but you settled on your own views after doing this research and you've held them for too long. It's like trying to convince someone that their religion they've known since birth is incorrect...you won't succeed no matter how logical an argument you offer up.

[Beer Baron]

You are all wrong. well troy is right, you are all flogging a dead horse. does anyone other than a guy competing in class based motorsport really care about this stuff. the real interest should be in how it drives, how it feels, what kind of sounds it makes, how much power and torque it makes and where and how it makes them. that's what's important to me. I couldn't give a shit if my rotary or piston engine was 1L 3L or bloody 30L, if it sounds good, goes good and runs reliably I'm happy.

give it up. you will never agree.

[madbung]

Do you have anything information-wise to contribute to the discussion or are you just trying to hook up with Gary? That's twice now I've seen you suck his dick in this thread without actually adding anything to support his case. It's starting to get annoying. From our point of view it's giving an ape a hammer and him not getting past the fact it isn't a screwdriver.

I'm sorry Gary but I'm just seeing too much fallacy in your argument...you change terms and context to suit your point of view. I'm hard pressed to say you don't have some sort of vested interest in this argument...I'd say it has alot to do with the fact you've held thse beliefs for so long, whereas the people arguing against you are flexible in their knowledge and willing to accept the alternative should it exist. You can say you were open minded and ignored everything Mazda gave the public to work with...but you settled on your own views after doing this research and you've held them for too long. It's like trying to convince someone that their religion they've known since birth is incorrect...you won't succeed no matter how logical an argument you offer up.

Quoted for fun.

Birds ode to the wankel....truly epic.

Mmm serious stuff...

If you're intelligent enough to recognise the futility of the argument why continue?

Serious discussions re: hammers/screwdrivers and the internet rarely equate to anything of value (hardly a revelation)

Yawn, thx for the read..the insults were amusing.

[GT-R32]

Hilarious post Birds. I'd rather let the groupies' posts reflect on them as individuals. But what you said was funny as.

Gary will not be able to understand your points. For some peculiar reason he thinks engines aren't rated using shaft degrees - yet he rates them according to exactly that.

A 13B inhales as much air as a 1308cc two stroke, with its two 'rotary pistons', it has no empty strokes unlike a 4 stroke. Indeed, one could then argue why Mazda should increase their rating, just because there are no wasted strokes that a 4-stroke has?

This is different to full displacement rated by Otto cycles, as it merely looks at volume of air/fuel inhaled for the each of the two rotary piston power strokes. Of course, a 4 stroke needs twice the 1308cc real surface/volume-ratio measure in the combustion chambers to be an 'equal'.

Mazda chose to rate the engine on this basis. Which, of course, compliments its packaging advantages. It creates enough air and exhaust heat to easily spool up big frame turbos. Not sure how any of this leads to 'Mazda lies'?

[Birds]

You are all wrong. well troy is right, you are all flogging a dead horse. does anyone other than a guy competing in class based motorsport really care about this stuff. the real interest should be in how it drives, how it feels, what kind of sounds it makes, how much power and torque it makes and where and how it makes them. that's what's important to me. I couldn't give a shit if my rotary or piston engine was 1L 3L or bloody 30L, if it sounds good, goes good and runs reliably I'm happy.

give it up. you will never agree.

Well I don't know about the others but I've acknowledged that these variables are the only ones that actually matter to people, only motorsport involved folk give a shit about the displacement.

Quoted for fun.

Birds ode to the wankel....truly epic.

Mmm serious stuff...

If you're intelligent enough to recognise the futility of the argument why continue?

Serious discussions re: hammers/screwdrivers and the internet rarely equate to anything of value (hardly a revelation)

Yawn, thx for the read..the insults were amusing.

There's no futility in the argument, there's futility in changing Gary's mind. I'm laying down my side of the argument, not to change his mind, but to keep ignorance and misleading information out of the thread for those reading it. Also to affirm my own knowledge. We have alot of blind Gary supporters who are gonna go passing on some bullshit about rotaries carrying significantly more displacement and Mazda lying about this...which will then find its way into some ignorant complaint made to homologation motorsport. And...I never said it wasn't fun participating in arguments...how else am I going to kill a work break? Shutting down people with logic is a favourite past time.

[Granthem]

f**k the two stroke debate.

Every skeptic has now admitted the 13B is not a 1.3ltr... its 3.9. Done

[GT-R32]

f**k the two stroke debate.

Every skeptic has now admitted the 13B is not a 1.3ltr... its 3.9. Done

What? Are you sure? I mean a 13B enhales 1.3L of air per crank rotation and once both rotary pistons have completed a power stroke.

See what I did there.

[Sydneykid]

Martin it's a somewhat pointless cause as some individuals are unlikely, or unable to for various personality, belief and morality based reasons, accept that they are wrong (although in this case, part right) and learn something.

I learn something new every day,

You would be flat out insane to look at the rotors, that's like looking at piston speed to determine RPM. Except just because it rotates, it confuses the casual observer. You have to look at the shaft to determine RPM. How does the engine sound at 9,000RPM? Listen to that Mikac 20B in the video I posted a few pages back.

Am I "flat out insane" to have bothered to find out that the rotors only do 3000 rpm. Or am I "flat out insane" to have bothered to educate people that the rotors only do 3000 rpm? I'm not sure how you measure insane, but I can't see how knowledge gained or passed on about how a rotary truly works is insane.

Sound, you dare to use sound, in a vain attempt to discredit what I posted, when in fact sound actually supports what I said. The sound you hear is combustion, not 9000 rpm of eccentric shaft rotation but 3,000 rpm of combustion. Because that's how many rpm the combustion medium is doing.

At this point a lesser person than me would loose control and insult your intelligence for being stupid enough to use an example that supports my argument. But I won't do that, I will simply say thanks for your support and for providing a perfect example of why I'm right.

[

Anything else is wrong and is not something you would learn anywhere, in any mechanical engineering degree, but I guess here you can on the internet if it serves your agenda.

My agenda is quite simple, I am just pointing out the alternatives to Mazdas 40 years of marketing spin on rotaries, showing that there is more than one way to express a rotaries capacity, rpm and cycle process. That Mazdas is wrong, deliberately wrong in fact, that's why I call it lying.

This applies to all engines and from there you have the ability to 'equalise' them as many motorsport bodies have done.

If only that were true. As I posted 10 pages or so back, equivalency is a fallacy.

Cheers

Gary

[Sydneykid]

What? Are you sure? I mean a 13B enhales 1.3L of air per crank rotation and once both rotary pistons have completed a power stroke.

See what I did there.

Pardon me for having some fun at your expense.

I didn't know 13B's had a crank, wow I learnt something today.

I didn't know 13B's had pistons, wow I learnt 2 things today.

I'm not sure that I need to know what enhale is though, I might pass on that bit of knowledge.

Cheers

Gary

[bozodos]

I think we're all forgetting that this is a thread about why rotaries suck, rather than an existential discussion about what "is" a 2 stroke a 4 stroke or a rotary engine etc etc. Nor is it an RX-7 appreciation thread. Therefore anyone who wasn't bashing Mazda's or rotaries in general is wrong, and should gtfo

[Birds]

^ would I be accurate in saying they suck because the induction creates a vacuum pressure inside the intake manifold?

[FineLine]

if rotors lasted as long as this thread I doubt we would be even reading this.

[GT-R32]

I learn something new every day,

Am I "flat out insane" to have bothered to find out that the rotors only do 3000 rpm. Or am I "flat out insane" to have bothered to educate people that the rotors only do 3000 rpm? I'm not sure how you measure insane, but I can't see how knowledge gained or passed on about how a rotary truly works is insane.

Sound, you dare to use sound, in a vain attempt to discredit what I posted, when in fact sound actually supports what I said. The sound you hear is combustion, not 9000 rpm of eccentric shaft rotation but 3,000 rpm of combustion. Because that's how many rpm the combustion medium is doing.

At this point a lesser person than me would loose control and insult your intelligence for being stupid enough to use an example that supports my argument. But I won't do that, I will simply say thanks for your support and for providing a perfect example of why I'm right.

Like Rice with the capacity question, you have failed to answer the important question that shows without doubt that shaft rpm is irrelevant in measuring capacity. That's the 2 stroke versus 4 stroke piston engine capacity. Let me have another go, because I live in hope that like Rice and Smtty42 you will see the factuality in what I said.

Mazda are the only engine manufacturer that uses shaft rotation to determine the capacity of engine. Even then they got it wrong, because the maths says 2.6 litres not 1.3 litres. Show me where any engine manufacturer multiplies the pumping capacity of a 2 stroke by the shaft rotation to get double it's capacity and published that as its true capacity? You can't, I know you can't, you know you can't, so you avoid the question. Well it's put up or shut up time.

This space left blank for GT-R32 to post up a list of engine manufacturers who publish anything but the pumping capacity of their 2 stroke engine.

My agenda is quite simple, I am just pointing out the alternatives to Mazdas 40 years of marketing spin on rotaries, showing that there is more than one way to express a rotaries capacity. That Mazdas is wrong, deliberately wrong in fact, that's why I call it lying.

If only that were true. As I posted 10 pages or so back, equivalency is a fallacy.

Cheers

Gary

When you measure capacity, how do you know a piston is at TDC? How do you know it's at BDC? Shaft degrees. Shaft rotation. How can you continue to dispute that? And that is how you measure displacement. How can you miss such an obvious point and imply I am wrong?

How does sound support your argument? The sound comment was to show you that they don't waste a stroke. Something which is (also) drastically confusing you.

Your question makes no sense. Unlike you, I have no hang-ups about Mazda's rating. Instead, I am merely dealing with technical facts of this engine. You have changed your tune several times and continue to now - such as "the rotary is a 3.9L 2 stroke", "rotary is a 6.8L V8 equivalent", "the rotary is not a 2 stroke" - all this serves is to bring the argument around in circles and hide that you either don't know what you are talking about, or don't want to admit you were wrong in the first place.

The air/fuel volume of a 13B is 1308cc for each shaft revolution (proven 100% relevant above), with both rotary-pistons having completed a power pulse. Answer me this, do you dispute this point?

You can't, it's a fact. Mazda chose to rate the engine on this basis.

Pardon me for having some fun at your expense.

I didn't know 13B's had a crank, wow I learnt something today.

I didn't know 13B's had pistons, wow I learnt 2 things today.

I'm not sure that I need to what enhale is though, I might pass on that bit of knowledge.

Cheers

Gary

If you had read some older texts you would realise that the term 'rotary piston' is in fact reference to the rotor and the name is used interchangably. The Mazda R100 came out in Australia with stickers on the promo vehicles that said "Rotary Piston Engine" or words to that effect. Try not to laugh at things you don't understand.

Crankshaft, e-shaft, or shaft. You knew what I meant. Whatever leads to the output shaft, you know, the thing you ignore and assume engine manufacturers do also, yet magically calculate displacement without it?

[GT-R32]

In one revolution of the rotor they inlet, combust and exhaust. That's a 2 stroke, no argument.

Check it out, you'll find I'm right

LOL

You're not. As has been proven.

There are no cylinders in a rotary. The capacity of an engine is simply how much does it pump in one cycle (360 degrees) and in the case of a 13B that's 3.9 litres.

LOL

It pumps 1308cc. Proven.

A 2.4 litre F1 engine make 700 bhp, with no turbos required. A 2.6 litre Indy Car V8 makes 800 bhp at 7psi. There are plenty of RB26’s at 2.6/2.8 litres that make a 1000 bhp and at 3 litres lots of 2JZ’s regularly make 1200+bhp. Put in to that context, a 3.9 litre turbo rotary is pretty average at 1000 bhp. Then there is the fact that it’s a 2 stroke, that means twice as many firings per cycle, so it should really be compared to a 6.8 litre 4 stroke. In which case 2500 bhp is more like it.

LOL

Again demonstrates you have no idea what you are talking about. But you are still here arguing. It's cute.

Cheers

Gary

Do you still believe all that Gary? It appears you do, but only sort of?

[Sydneykid]

I agree. A 13B should be known as a 3.9L Wankel.

OK, so now I have converted Rice, Smitt42 and GT-R32 to the truth that a 13B should be known as a 3.9 litre rotary engine. (Which of course is what I posted 20 pages or so back). All that's left is Birds, common over from the dark side and step into the light of knowledge, you're welcome too.

So what's left in this quest...........the rotors only do 3,000 rpm................no, won that one already.

That only leaves one of my points to get agreement on, the ever difficult 2 stroke/cycle. It's hard because the rotary huggers like to throw in irrelevancies to muddy up the water, or use narrow meanings of words to stop comparisons, or when I try and use different words to help them gain understanding they accuse me of changing the terminology. This is the most difficult of the 3 arguments to win, because there are so many ways for them to get out of jail

Now we all know rotaries need oil in the combustion chamber like a 2 stroke/cycle engine. But that's not really enough evidence. We all know they sound like a 2 stroke, But that's not really enough evidence, but wait is it? Not in itself, but it is an indicator of something important. Every time a rotor face goes "past" the exhaust port it exhausts. Just like every time a 2 stroke/cycle piston goes "past" the exhaust port it exhausts. But in a 4 stroke it's only every second time the piston goes "past" the exhaust port it exhausts. I suppose they will pick on the generalisation of the word "past" because 4 strokes have valves so the piston doesn't go past the exhaust port it goes past the exhaust valve. Knit picking but I bet they use it to get out of jail.

How about this then. Every time a rotor's combustion face goes past the spark plug it fires. Just like every time a 2 stroke/cycle piston's combustion face goes past the the spark plug it fires. But in a 4 stroke it's only every second time the piston's combustion face goes past the spark plug that it fires. That's a bit better, no confusion with what "past" means, a spark plug is spark plug. Except rotaries have 2 of those, perhaps they will use that as an escape. Surely not, that's really grasping at straws. Let's see what they come up with this time.

Cheers

Gary

[Sydneykid]

When you measure capacity, how do you know a piston is at TDC?

It's at the top of the bore.

That's what the "T" means (ie; TOP).

Any engine builder will tell you that TDC is always measured at the piston

How do you know it's at BDC?

It's at the bottom on the bore.

That's what the "B" means (ie; BOTTOM).

Shaft degrees. Shaft rotation. How can you continue to dispute that?[/size] And that is how you measure displacement. How can you miss such an obvious point and imply I am wrong?

I'm not mising it, I'm ignoring it, because it's irrelevant.

How does sound support your argument? The sound comment was to show you that they don't waste a stroke. Something which is (also) drastically confusing you.

I don't se any wasted strokes in a 4 stroke, one is inlet the other is exhaust. Both strokes serve a very useful purpose.

Your question makes no sense. Unlike you, I have no hang-ups about Mazda's rating. Instead, I am merely dealing with technical facts of this engine. You have changed your tune several times and continue to now - such as "the rotary is a 3.9L 2 stroke", "rotary is a 6.8L V8 equivalent", "the rotary is not a 2 stroke" - all this serves is to bring the argument around in circles and hide that you either don't know what you are talking about, or don't want to admit you were wrong in the first place.

Your answer makes no sense. Unlike you, I have no hang-ups about Mazda's marketing. Instead, I am merely dealing with technical facts of this engine. You have changed your tune several times and continue to now - such as "the rotary is a 1.3L, "rotary is a 3.9 l", all this serves is to bring the argument around in circles and hide that you either don't know what you are talking about, or don't want to admit you were wrong in the first place.

The air/fuel volume of a 13B is 1308cc for each shaft revolution (proven 100% relevant above), with both rotary-pistons having completed a power pulse. Answer me this, do you dispute this point?

So what

You can't, it's a fact. Mazda chose to rate the engine on this basis.

And in doing so lied about the true pumping cpacity of the engine.

If you had read some older texts you would realise that the term 'rotary piston' is in fact reference to the rotor and the name is used interchangably. The Mazda R100 came out in Australia with stickers on the promo vehicles that said "Rotary Piston Engine" or words to that effect. Try not to laugh at things you don't understand.

Crankshaft, e-shaft, or shaft. You knew what I meant. Whatever leads to the output shaft, you know, the thing you ignore and assume engine manufacturers do also, yet magically calculate displacement without it?

I was jerking your chain, because you accused me of changing terminology and then you go and do it yourself.

Thge difficulty you are having is that you are hung up on shaft revolutions for a rotary as being relevant to capacity but you accept that shaft revolutions don't mater in a 2 stroke versus 4 stroke piston capacity. On the other hand I ignore shaft revolutions in all capacity measurements. I'm being consistent in my approach and you aren't.

Cheers

Gary

[fuzzy_scuz]

The difficulty you are having is that you are hung up on shaft revolutions!!!!!!!

Enough said