Why Do Rotaries Suck?

[Sydneykid]

  Jez13 said:

But for every 2.6ltrs makes two shaft revolutions, not one.

Then compare that with a 2.6 litre 4 stroke piston engine. The same, 2 revolutions of the crankshaft, but we don't call it a 1.3 litre.

Cheers

Gary

[Jez13]

  Sydneykid said:

Then compare that with a 2.6 litre 4 stroke piston engine. The same, 2 revolutions of the crankshaft, but we don't call it a 1.3 litre.

Cheers

Gary

But its not 4 strokes per combustion its only 2 on a rotory. And if it where a 3.9ltr it would be a six stroke.

[GT-R32]

  Jez13 said:

But its not 4 strokes per combustion its only 2 on a rotory. And if it where a 3.9ltr it would be a six stroke.

And so we end up with what I posted back about 5 pages ago.

A 13B is equivalent to:

1.3L 2 stroke.

2.6L 4 stroke.

3.9L 6 stroke.

[Jez13]

  GT-R32 said:

And so we end up with what I posted back about 5 pages ago.

A 13B is equivalent to:

1.3L 2 stroke.

2.6L 4 stroke.

3.9L 6 stroke.

LOL. We just have to keep on pushin! Choo choo!

[Sydneykid]

  GT-R32 said:

Decent post Gary, until you got to the 'Mazda lie' stuff again. Remember the engine is on licence from NSU and Dr Wankel.

That doesn't stop Mazda from stating the true capacity

  Quote

1308cc comes from combustion chamber volume x2. That's pretty clear I thought.

The depeends on the definition of combustion chamber. Obviously a chamber has more than one side and in a rotary engine the part of the combustion chamber that is stationary, the housing, is the smaller part. The vast majority of the combustion chamber is in fact made up by the 3 sides of the rotor and the combustion bowls cast into each one of those 3 sides. So in a rotary engine the majority of the combustion chamber rotates with the rotor. Hence it really has 3 combustion chambers.

You can’t call the entire rotor housing the combustion chamber because it also contains inlet, compression and exhaust processes. Only one part if it, the minority, is involved in the combustion part of the cycle.

Cheers

Gary

[Sydneykid]

  GT-R32 said:

And so we end up with what I posted back about 5 pages ago.

A 13B is equivalent to:

1.3L 2 stroke.

2.6L 4 stroke.

3.9L 6 stroke.

My turn, but a rotary doesn't stroke.

Since we are quoting thread history, it's a 3.9 litre 2 stroke/cycle engine.

Shall we go back to page 1 and start again?

Cheers

Gary

[Jez13]

  Sydneykid said:

That doesn't stop Mazda from stating the true capacity

The depeends on the definition of combustion chamber. Obviously a chamber has more than one side and in a rotary engine the part of the combustion chamber that is stationary, the housing, is the smaller part. The vast majority of the combustion chamber is in fact made up by the 3 sides of the rotor and the combustion bowls cast into each one of those 3 sides. So in a rotary engine the majority of the combustion chamber rotates with the rotor. Hence it really has 3 combustion chambers.

You can't call the entire rotor housing the combustion chamber because it also contains inlet, compression and exhaust processes. Only one part if it, the minority, is involved in the combustion part of the cycle.

Cheers

Gary

Correct Gary your comming around. And that small part is located just inside the exhaust port at the bottom left of the rotory housing. Ha! A mobile combustion champer? We dont call the surface of a piston the combustion chamber and we dont call the ceiling of the bore a combustion chamber, its the space thats in-between the piston and the bore cieling that makes the combustion chamber. And that space is located on a rotor in the bottom left hand corner of the rotor housing.

[madbung]

Mmmm top, bottom, walls. yes they all define the size of the combustion camber.

flat tops or dished pistons do contribute to the size of the combustion chamber and are a part of such.

The same goes for the rotar and it's housing.

Edited October 2, 2009 by madbung

[Jez13]

  Sydneykid said:

My turn, but a rotary doesn't stroke.

Since we are quoting thread history, it's a 3.9 litre 2 stroke/cycle engine.

Shall we go back to page 1 and start again?

Cheers

Gary

If your page one is correct - but it isnt:

The term “stroke” in this context refers to how many times the crankshaft or eccentric shaft makes a piston go up or down to complete the cycle or for a rotory to go around and around.

1. Let’s sum this up in a simple chart to visually explain how this works:
   
2. 2 stroke engine (up, down) – 1 complete crankshaft revolution.
   
3. 4 stroke engine (up, down, up, down) – 2 complete crankshaft revolutions.
   
4. 6 stroke (rotary) engine (up, down, up, down, up, down) – 3 complete crankshaft (eccentric shaft) revolutions.
   

[GT-R32]

  Sydneykid said:

My turn, but a rotary doesn't stroke.

Since we are quoting thread history, it's a 3.9 litre 2 stroke/cycle engine.

Shall we go back to page 1 and start again?

Cheers

Gary

I used the word 'equivalent' which makes my comments very clear.

Absolutely nowhere is it accepted that a rotary is a 2 stroke/cycle. It isn't. It completes the 4 Otto cycles or four-stroke combustion cycles, just in a different way.

[Jez13]

  madbung said:

Mmmm top, bottom, walls. yes they all define the size of the combustion camber.

flat tops or dished pistons do contribute to the size of the combustion chamber and are a part of such.

They contribute but they are not a combustion chamber by themselves.

[GT-R32]

  Jez13 said:

They contribute but they are not a combustion chamber by themselves.

Static compression ratio has nothing to do with displacement or capacity.

[Birds]

  Sydneykid said:

No we haven't, that's why Mazdas doesn't run at LeMans anymore, a fight over true capacity.

That's why there were no rotaries in F1 in the 70's, a fight over true capacity.

Thats's why motorsport authorities world wide apply multipliers to Mazda's stated capacity.

So whether or not "this person" wanted it classified correctly or not isn't important, the fact is plenty of organisations, important ones, do.

Their not worried because they know it's 4.0 litre engine with a turbo. The 4.0 litre capacity is on the front guard of Fords. Why do Ford bother making a badge and puting on the front guard? Because capacity is relevant to their buyers. They are not being lied to. Ford doesn't say it's a 2 litre engine, because it only fires every second revolution of the crankshaft. It's 4.0 litre and Ford promote it as such. If capacity was as irrelevant as you would have us believe then Ford would save some money delete all engine capacity badges and not promote them,

That's the important point, they all state the true capacity and then qualify it with whether it's a diesel or turbocharged or supercharged or intercooleed or maybe all of the above. In all cases, but one, the starting point is the true capacity of the engine. It's where the basis starts, then the qualifiers are added. Except in one case, Mazda modify the capacity first, then add the qualifiers.

My point is Mazda should say "3.9 litre rotary engine", because that's what it is. Even if you subscibe to the 1080 versus 760 degrees of shaft rotation theory then Mazda should say "2.6 litre rotary engine". But they don't and that's why I object and why I call it a lie.

If, as you claim, capacity is "somewhat irrelevant" then why shouldn't/didn't Mazda state the true capacity? The answer is obvious, Mazda obviously consider it relevant and that makes your opinion irrelevant.

Displacement is used in badging on cars because there was once a time when it was relevant as an indicator of the cars performance/economy. It's old hand and mostly continued for tradition. Also, sometimes the only difference (and therefore differentiation) between two models of car is the size of the engine...so how else would you like them to badge it? You'll seldom find it on vehicles that only come with one size of engine. Look at the marketing wars between HSV and FPV too when it comes to their vehicle badging...it's all about stating the power, because in a market where power matters that's what the people want to know...not displacement.

In all cases, but one, the starting point is the true capacity of the engine? Yeah well, it's a nice coincidence that this one case is a unique engine that no other mainstream vehicle manufacturer uses in their automobiles.

I'm not seeing your point Gary...rotaries are allowed to compete in plenty of racing categories world wide. And all your examples do is reiterate my point that they are such a unique engine, not even international motorsport bodies can agree on the true displacement for them and an appropriate class.

Did you ever stop to think Mazda didn't state the "true" 3.9 litre capacity because it quite validly isn't the true capacity of the engine? You have somewhat of an egocentric view on this, as if the world should recognise your method for calculating the displacement of a rotary.

  madbung said:

.... and you label Gary pedantic.

Displacement is displacement. It can be referred to it as swept volume if you prefer but it's all the same calculation regardless of bore/stroke ratios.

Yes to re-iterate myself "Different bore and stroke formulas can have equal displacement but vastly different performance, I know amazing hey." We are discussing how to calculate an engines cubic,cc,litre capacity/displacement here are we not? or have we switched over to power/torque output formula's along with your turbocharged tangent?

Yes evaluating an engine comes down to displacement,output (power) and efficiency but that is not the question at hand is it?

A duck will always be a duck just as a goose will always be a goose.. Please stop trying to paint this duck up to look like a goose.

I realise you love a good debate, but why not let common sense and the recognised "standard" prevail this time.

Umm...what exactly is pedantic about that?

The same calculation? Madbung, do us the favour of explaining how to calculate the displacement of a rotary. And don't just tell me 6 times the volume of an individual chamber...I'd like to know the formula for working out the bore and stroke of an individual combustion chamber in a rotary. Do you think it might be a bit more complex than multiplying the bore and stroke in a piston engine with pi? I think so too. In fact, I'd wager you can hardly call it a bore or a stroke. That to me opens the gates for more than one method of calculating displacement.

That is the question at hand. And it's quite valid to bring power and torque into it because as engine outputs they are what is relevant for the consumer. Your point is that Mazda are lying to people. My point is they aren't, and even if they were, no one gives a shit. I'm still waiting for these pissed of RX7 owners...please find them for me.

I laugh everytime you people dismiss any sort of argument that might shut down yours as "muddying the water" or "painting things up differently" instead of actually arguing back with facts or explaining your reasoning. It makes for very poor debate.

Guess what, the recognised standard: a 13B is 1.3 litres. I'm not the one who has to deal with the teenage rebellion, emo complex hate-on for a manufacturer inside my head. You guys are going against decades of Mazda cementing in place this engine is a 1.3 litre engine. Enjoy your fight with that one...

[Sydneykid]

  GT-R32 said:

I used the word 'equivalent' which makes my comments very clear.

Absolutely nowhere is it accepted that a rotary is a 2 stroke/cycle. It isn't. It completes the 4 Otto cycles or four-stroke combustion cycles, just in a different way.

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

[madbung]

Ahh ffs Birds, true to form another epic about nothing.

  Jez13 said:

They contribute but they are not a combustion chamber by themselves.

Bore or block walls, piston and head do not make up the combustion chamber ? go figure

  GT-R32 said:

Static compression ratio has nothing to do with displacement or capacity.

correct add them all up to evaluate an engine but it is not relative to its displacement or swept volume.

Edited October 2, 2009 by madbung

[Smity42]

  Sydneykid said:

My turn, but a rotary doesn't stroke.

Since we are quoting thread history, it's a 3.9 litre 2 stroke/cycle engine.

Shall we go back to page 1 and start again?

Cheers

Gary

  GT-R32 said:

I used the word 'equivalent' which makes my comments very clear.

Absolutely nowhere is it accepted that a rotary is a 2 stroke/cycle. It isn't. It completes the 4 Otto cycles or four-stroke combustion cycles, just in a different way.

And its not even close to the equivalent of a 3.9L 2 stroke... Thats just wrong

SYDNEYKID, you seem to love calling it a 2 stroke/cycle. IN WHAT WAY DOES 2 CYCLES HAVE ANYTHING TO DO WITH THE ROTORS COMBUSTION PROCESS?

It completes its combustion process in ONE cycle of the rotor, NOT TWO

[madbung]

Personally I have no opinions on Mazda's "lies" I'd be happy if some posters would recognize displacement as the industry standard it is regardless of Mazda's devious machinations.

[Jez13]

  Sydneykid said:

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

Haha gary, the difference is one piston can't intake and extract at exactly the same time where as a 1 rotor can. Thats why your theory doesnt apply.

Yes it has 3 chambers but only one of the chambers is a combustion chamber.

[Birds]

I'd be happy if certain posters recognised that advent and invent of new engine design alters the way in which you can measure total displacement. There's no universal way of doing it...the rotary is NOT a piston engine. Fullstop.

[Sydneykid]

  Jez13 said:

Correct Gary your comming around.

Nope

  Quote

And that small part is located just inside the exhaust port at the bottom left of the rotory housing.

Oh my, you really don't know the anatomy of a rotary engine all that well, best you pop back to the diagram of how a rotary really engine works

  Quote

Ha! A mobile combustion champer?

What it is, is what it is.

  Quote

We dont call the surface of a piston the combustion chamber and we dont call the ceiling of the bore a combustion chamber, its the space thats in-between the piston and the bore cieling that makes the combustion chamber.

And in a rotary engine that space rotates (orbits if you prefer) with the rotor.

  Quote

And that space is located on a rotor in the bottom left hand corner of the rotor housing.

No it's not, even by your flawed definition it's not.

Cheers

Gary