Why Do Rotaries Suck?

[GT-R32]

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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.

Mate, sorry. You never converted me. RICE has been beating this drum far longer than you have (since the early 1990s), I have known the man for nearly 10 years now. Indeed he has done it with great technical merit using concepts you fail to understand (revolutions and relatives to time). Eventually, he made this post:

http://www.ausrotary.com/viewtopic.php?f=3&t=158905

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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

Gary, the silly thing is we agree on the 3.9L full (Wankel) cycle. Your failing is somehow thinking that the shaft revolutions are irrelevant and call the engine a 2 stroke. They simple aren't on any technical level.

[Granthem]

So we all agree a rotary is a 3.9 litre engine? yah?

And its not a 2 stroke... or a 4 stroke... its a wankel!

[GT-R32]

So we all agree a rotary is a 3.9 litre engine? yah?

And its not a 2 stroke... or a 4 stroke... its a wankel!

100%.

[Birds]

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.

F*** no. Your idea of knowledge is to ignore valid points and pay attention to only that which you want to hear. You also have a nasty habit of assuming you've "won" an argument. Typical engineer's ego. It's like you cover your ears, close your eyes and scream "I'm not listening, I'm not listening, you're wrong, you're wrong, why would you lie, why would Mazda lie". Why on Earth would I want a part in that?

What's left in this quest? How about every flawless argument I've presented you with that you choose to ignore. I think the last 23 pages are well representative of my ability to sustain my argument, so I'm going to leave it at that and let the audience decide for themselves, if they can be bothered reading this massive waste of space. By all means refute my last few points should you wish to have the last word in it all...but I'm going to spectate from now on (though I will probably be back knowing how much I love to shoot down poor arguments in flames).

I was just about to say we're due for another token one-liner, SAU Gary c*** sucker, but it looks like someone beat me to it.

[Granthem]

100%.

Excellent. that seems the most realistic thing.

A rotary is like an alien compared to a piston engine, so trying to compare their workings and convert them to whichever stroke seems pointless to me.

This thread has been extremely helpful for me to understand rotaries tho... I had a fair idea, but seeing the pics of the degrees etc was extremely beneficial.

And now everyone knows why they make so much damn power, and turn such huge turbos!

[jase-r34]

I learnt to measure an engine's capacity by calculating the amount of swept volume in one combustion chamber, and multiplying it by the amount of chambers. Never heard anything about the crankshaft mentioned in that regard.

[madbung]

I generally use the "cc" method myself.

Easy and fairly accurate for volume/displament measuring in the shed.

Hardly the thing for modern automotive engineering though...I guess

Edited September 25, 2009 by madbung

[~rx3~]

Interesting history there. Phil Irving OBE, Repco Brabham designer, author of many books, actually did a study on rotary engine capacity in the '70's. Based on sound automotive principles he arrived at a capacity of ~3.2 litres for a 12A.

Cheers

Gary

do you know how he worked this out ,because a 12a is 1146 ,x3 =3.438

[ylwgtr2]

F*** no. Your idea of knowledge is to ignore valid points and pay attention to only that which you want to hear. You also have a nasty habit of assuming you've "won" an argument. Typical engineer's ego. It's like you cover your ears, close your eyes and scream "I'm not listening, I'm not listening, you're wrong, you're wrong, why would you lie, why would Mazda lie". Why on Earth would I want a part in that?

What's left in this quest? How about every flawless argument I've presented you with that you choose to ignore. I think the last 23 pages are well representative of my ability to sustain my argument, so I'm going to leave it at that and let the audience decide for themselves, if they can be bothered reading this massive waste of space. By all means refute my last few points should you wish to have the last word in it all...but I'm going to spectate from now on (though I will probably be back knowing how much I love to shoot down poor arguments in flames).

I was just about to say we're due for another token one-liner, SAU Gary c*** sucker, but it looks like someone beat me to it.

Thats a bit harsh.....but it did make me laugh

Edited September 25, 2009 by ylwgtr2

[GT-R32]

I learnt to measure an engine's capacity by calculating the amount of swept volume in one combustion chamber, and multiplying it by the amount of chambers. Never heard anything about the crankshaft mentioned in that regard.

That would leave you with 1308cc for a 13B. 2x 654cc combustion chambers. And funnily enough it's what Mazda use, LOL. Using this will give the rotary an advantage, which is Gary's beef.

To equalise the Wankel to a 4 stroke in a simple, theoretical sense, you need to double this as the Wankel makes power from both chambers for every revolution (360 degrees) of the (crank) shaft, where a 4 stroke will not (720 degrees). This is the relative time scale to output that some people really battle with. FYI, this doesn't take into account rotary efficiencies as CAMS and FIA do a x1.79.

[jase-r34]

That would leave you with 1308cc for a 13B. 2x 654cc combustion chambers. And funnily enough it's what Mazda use, LOL. Using this will give the rotary an advantage, which is Gary's beef.

No I wouldnt because a rotor has 3 combustion surfaces and there are 2 rotors. Therefore is it 6 x 654 = 3.9L.

[GTR-32U]

No I wouldnt because a rotor has 3 combustion surfaces and there are 2 rotors. Therefore is it 6 x 654 = 3.9L.

Very much what I calculate it being as well.Now as to wether its a 2 stroke or 4 stroke...? It definately isnt a 4 stroke , Its a lot closer to being a 2 stroke but isnt quite there yet either.....Had it only have had 2 sides to the rotor I would then be calling it a 2 stroke but this isnt the case..With the Rotor being Triangular and having a 3rd face it throws the whole lot out...Its almost like a 1 and a 3rd stroke engine.....will keep an eye on this thread...interesting

[camspeed]

[/size]

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.

[GT-R32]

No I wouldnt because a rotor has 3 combustion surfaces and there are 2 rotors. Therefore is it 6 x 654 = 3.9L.

You said combustion chamber, originally. That's place where the 'surfaces' pass through for their power pulse. I do agree that all sides should be counted in displacement.

LOL Cam.

[AGE]

I'll be honest i only made it throught the first 10 pages, then the last 4 pages...but,

They don't suck.

It's the small minded people that don't know anything about them that give them a bad wrap. I have owned 3 and I never had a single problem with them at all and I dare say the people that bad mouth them have never even owned one.

Just like anything mechanical (and female) they can have issues when mistreated.

Agreed. I've owned 3 Rotary's and they were the most fun I've ever had with cars. I've even destroyed a engine @ 110 kph (i stripped the teeth from the stationary gear), and it still would start....yes it would only idle @4k+ , but it still would start.

It's like anything, look after it and it will look after you.

Can you get diesel rotaries?

Short Answer...no, with a but.

Long Answer.... Yes, with a shitload of $$$, R&D and added weight.

[jase-r34]

You said combustion chamber, originally. That's place where the 'surfaces' pass through for their power pulse. I do agree that all sides should be counted in displacement.

LOL Cam.

Lol smart ass! Well you know what I meant!

[GT-R32]

Lol smart ass! Well you know what I meant!

I know exactly what you meant. But it all needs to be in perspective.

See the following for a RX8:

It compares to a 1.3 litre two stroke. 360 degree crank rotation completes cycles.

It compares to a 2.6 litre four stroke. 720 degree crank rotation completes cycles. <-- learn more about the engine in your car if you don't get this!

It compares to a 3.9 litre six stroke. 1080 degree crank rotation completes cycles.

Look at this and think about how it fires:

The bar at the bottom sums it up. The rotary-pistons might only 'rotate' at 3000RPM for the 9000RPM where the BHP is measured, but the rotor fires 3 times per revolution (3x 3000 of 654cc x2) and once per crank revolution (9000 x 654cc x2). Hence the noise - where it reflects 9000RPM of 654c x2 volume of combustion per revolution despite rotor speed (and as I have been saying is like discussing piston speed!).

[Sydneykid]

F*** no. Your idea of knowledge is to ignore valid points and pay attention to only that which you want to hear.

I'm sorry but I beleive I have addressed every one of your so called valid points and ober ruled them with alternative and valid mathematics, sound engineering principles

You also have a nasty habit of assuming you've "won" an argument. Typical engineer's ego. It's like you cover your ears, close your eyes and scream "I'm not listening, I'm not listening, you're wrong, you're wrong, why would you lie, why would Mazda lie". Why on Earth would I want a part in that?

Do you agree that a 13B is a 3.9 litre roatry engine? Please note that I am not asking you whether or not that's the same as a 3.9 litre piston engine. What I am asking you is very specific, is a 13B a 3.9 litre rotary engine or not.

The next question do the rotors in a 13B do 3,000 rpm (call it cycles or orbits if you wish) when the crankshaft is doing 9,000 rpm? Please note that I am not asking you whether or not that's the same as 3,000 rpm of the pistons in piston engine. What I am asking you is very specific, do the rotors do 3,000 rpm or not.

What's left in this quest? How about every flawless argument I've presented you with that you choose to ignore.

I haven't ignored them, I believe I have answered every one of them and given an appropriate alternative argument, justified and supported.

Of course you believe your arguments are flawless, just as I believe mine are. The difference is you are basing your arguments on the unque ways Mazda choose to value the capacity of their rotary engines. Which is not the same way as any other engien manufacturer. In fact it's not the same way as Mazda value the capacity of their other engines. Whereas I am basing my arguments on what every other engine manufacturer does. So yes, your arguments are flawless if you are only looking at how Mazda do it, but I have countered that with what every onther engine manufacturer does. that;s why I beleive my flawless arguments are more flawless than yours.

At this point I feel quite justifed in calling pot, kettle, black. You completely refuse to accept the undeniable fact that only Mazda with their rotary engines use eccentric shaft degrees to measure capacity. So if anyone is ignoring flawles arguments it's you.

I think the last 23 pages are well representative of my ability to sustain my argument, so I'm going to leave it at that and let the audience decide for themselves, if they can be bothered reading this massive waste of space. By all means refute my last few points should you wish to have the last word in it all...but I'm going to spectate from now on (though I will probably be back knowing how much I love to shoot down poor arguments in flames).

Well let's get on with it then, I'm still feeling fireproof.

BTW, I haven't quoted the last line of your post because I believe it contributes nothing to the discussion.

Cheers

Gary

[~rx3~]

The difference is you are basing your arguments on the unque ways Mazda choose to value the capacity of their rotary engines. Which is not the same way as any other engien manufacturer. In fact it's not the same way as Mazda value the capacity of their other engines. Whereas I am basing my arguments on what every other engine manufacturer does. So yes, your arguments are flawless if you are only looking at how Mazda do it, but I have countered that with what every onther engine manufacturer does. that;s why I beleive my flawless arguments are more flawless than yours.

Cheers

Gary

the way mazda value the capacity of the rotary engine is not unque, or unique to mazda .other manufacturers of rotary engines have done the same thing,so it is the same as other engien manufacturers or other engine manufacturers

Edited September 26, 2009 by ~rx3~

[260tech]

Bugger me. We finally have the answer. Those Wankels suck. Really hard! 3.9ltr worth per Wankel cycle. No wonder the little f@%kers go hard! And chew the gas?

Terrific read, most informative.

Thanks guys.