Why Do Rotaries Suck?

[fuzzy_scuz]

So that is why my friends fuel gauge drops when he sinks the boots in it.......

Now I get it........ it is using 2 litres more than specified by Mazda....

[Sydneykid]

So that is why my friends fuel gauge drops when he sinks the boots in it.......

Now I get it........ it is using 2 litres more than specified by Mazda....

You get it as well ,

But it is more like 3 times what is specified by Mazda.

Cheers

Gary

[GT-R32]

No they are not.

If they were, then a 2 stroke/cycle 1.3 litre would be a 2.6 litre

Or a 2.6 litre 4 stroke would be a 1.3 litre.

Nobody measures an engines capacity dividing or multiplying by the number of degrees the cranskaft rotates.

Actually that's not true, Mazda does, but only for rotaries, they don't do it for their 4 stroke engines.

Accurate? What's more accurate than how much the pump (the rotor) actually pumps? The eccentric shaft doesn't pump, the rotor does.

Let me help you out here with some numbers,

A 3.9 litre two stroke completes its Otto cycle in two distinct 'strokes' and does this in 360 degrees. Eveyrone calls it a 3.9 litre engine.

A 3.9 litre four stroke completes its Otto cycle in four distinct 'strokes' and does this in 720 degrees. Everyone calls it a 3.9 litre engine.

A 3.9 litre Wankel completes its Otto cycle for all rotor faces in 1080 degrees. Mazda call it a 1.3 litre engine.

Now explain that to me again, because it looks to me like one rule for Mazda and another rule for everyone else.

That's been my point all along. I'm just trying to ensure that eccentric shaft degrees are not used as the measure as they are irrelevant to everyone else except Mazda.

Cheers

Gary

I agree. A 13B should be known as a 3.9L Wankel. Where you are wrong is in drawing equivalents. You somehow think the engine is a 2 stroke? A two stroke completes its Otto cycle in 360 degrees.

How much air does a 13B inhale per 360 degree revolution of the crank?

[PM-R33]

Honestly the best example is the turbo one. 1.3L spooling up 700+HP turbos better than piston engines of double the displacement. That alone has to make you think what the hell is going on.

[camspeed]

I can't believe someone who seems so smart as SydneyKid does can be so stupid. And then come bigger groupies than RICE RACING has to lap it all up. Its not a f**king two stroke. Its a rotary.

So at the end of the day, we have an engine that is 3.9L, spools massive turbos, can make huge horsepower yet can still fit into a engine bay you wouldn't fit half an RB26 into.

Sounds pretty good to me

[bigmikespec]

I can't believe someone who seems so smart as SydneyKid does can be so stupid.

[jase-r34]

I can't believe someone who seems so smart as SydneyKid does can be so stupid. And then come bigger groupies than RICE RACING has to lap it all up. Its not a f**king two stroke. Its a rotary.

I think you need to go back and re-read Gary's posts.

[Munkyb0y]

cmon, even to me its painfully obvious! even without all your fandangled technical analysis.

a rotary guzzles fuel like its dole day at redfern

it creates so much exhaust, it NEEDS storm water pipes to get it all away

slap a massive turbo on the fkr, and it doesnt even flinch

there's no way this is equivalent to a 1.3L

Edited September 24, 2009 by Munkyb0y

[~rx3~]

1957 later

DKM 125 (125cc capacity) was constructed and achieved 26 horsepower at 15000rpm during testing. Another DKM engine was taken to 25000rpm in a special safety tunnel. how do you work out the rpm of this one ,the rotorhousing and the rotor rotate . maybe rotaries can do 9000

[ylwgtr2]

[~rx3~]

Lizenznehmer

21.10.1958 Curtiss & Wright Corp. *1) USA ohne Einschränkung

29.12.1960 Fichtel & Sachs AG BRD Industrie Motoren, Boot 0,5-30PS

25.02.1961 Yanmar Diesel Co. Ltd. JP Benzin + Diesel, 1-100PS, 1-300PS

27.02.1961 Toyo Kogyo, Co. Ltd. (Mazda) JP Benzin 1-200PS für Landfahrzeuge

04.10.1961 Klöckner-Humboldt-Deutz AG BRD Diesel ohne Einschränkung

26.10.1961 Daimler-Benz AG BRD Benzin 50Ps aufwärts

30.10.1961 MAN AG BRD Diesel ohne Einschränkung

02.11.1961 Fried. Krupp BRD Dieselmotoren ohne Einschränkung

12.03.1964 Daimler-Benz AG BRD Diesel-Motoren ohne Einschränkung

15.04.1964 S.p.A Alfa Romeo IT Benzin von 50-300 Ps Pkw

17.02.1965 Rolls-Royce Motors Ltd. GB Diesel und Hybridmotoren 100-850 Ps

18.02.1965 IFA VEB DDR Ottomotoren 0,5-25PS und 50-150PS.

02.03.1965 Dr.Ing. h.c. Porsche KG BRD Benzinmotoren von 50-1000 Ps

01.03.1966 Outboard Marine Corp. USA Benzinmotoren 50-400 Ps

11.05.1967 Comotor S.A. L Benzin- und Dieselmotoren 40-200PS

12.09.1967 Graupner BRD 0,1-3 Ps Modellmotoren

28.08.1969 Savkel Ltd. IS Benzinmotoren von 0,5-30 Ps Industrie-Motoren

01.10.1970 NISSAN Motor Company Ltd JP Benzinmotoren von 80-120 Ps

10.11.1970 General Motors USA Alles, außer Flugzeugmotoren

24.11.1970 SUZUKI JP Benzinmotoren von 20-60 Ps für Zweiräder

25.05.1971 TOYOTA JP Benzinmotoren von 75-150 Ps für Pkw

29.11.1971 Ford-Werke AG, Köln BRD Benzinmotoren 80-200PS (1974 gekündigt)

25.07.1972 BSA Ltd. GB Benzinmotoren 35-60PS für Motorräder

29.09.1972 Yamaha JP Benzinmotoren 20-80PS für Motorräder

04.10.1972 Kawasaki Heavy Ind. Ltd. JP Benzinmotoren 20-80PS für Motorräder

07.02.1973 American Motors Com. USA Benzinmotoren 20-200PS

*1) Unterlizenzverträge mit Curtiss-Wright

01.03.1966 Outboard Marine Corp. USA Otto-Motoren für Boots- und Industriemotoren

12.06.1972 Brunswick Corp. USA Otto-Motoren als Industriemotoren von 20 bis 100PS

27.07.1972 Ingersoll-Rand Co. USA Otto-Motoren als Antrieb von Pumpen, Kompressoren und

Generatoren, 350 bis 4500PS

07.02.1973 American Motors Corp. USA Landfahrzeuge (Otto-Motorren) von 80 bis 200PS all these companies got the right to make rotaries,from as small as the 1mm rotor micro rotary ,to lawnmower ,chainsaw,and snowmobile,engines ,uto the 41 litre ingersoll-rand gas rotary (or is that 123 liters) some just made a few prototypes, ,others went into production.are all these companies liars too?as someone who craps on about mazda lies, you shouldnt lie about them being the only one to make rotaries ,there are other companies that still make them.

[camspeed]

I think you need to go back and re-read Gary's posts.

Why? So I can read bullshit again?

[Sydneykid]

all these companies got the right to make rotaries,from as small as the 1mm rotor micro rotary ,to lawnmower ,chainsaw,and snowmobile,engines ,uto the 41 litre ingersoll-rand gas rotary (or is that 123 liters) some just made a few prototypes, ,others went into production.are all these companies liars too? as someone who craps on about mazda lies, you shouldnt lie about them being the only one to make rotaries ,there are other companies that still make them.

Show me where I said Mazda were the only ones to make rotary engines? In fact if you bothered to read what I actually wrote, you will know I specifically mentioned NSU and Norton with road going rotary engines. Like their piston competitors, the Fitchel and Sachs rotary engine (made by NSU) in the lawn mowers. the OS model aeroplane rotary engine and KM chainsaws were all rated for horsepower. I don't recall ever seeing a capacity rating for them. They competed with pistons engines purely on power, there was no attempt to sell them based on engine capacity. It certainly wasn't the main marketing thrust like Mazda did with their's. Interestingly the chain saws with rotary engines were too heavy and their sales died a quick death as a result. I do recall Yanmar having a rotary marine engine, I think it was diesel though.

BTW, from what I remember the Ingersoll-Rand gas rotary is a pump not an engine and guess what? It was rated by how much it pumped.

Cheers

Gary

[~rx3~]

they made compressors ,pumps, and generator assemblies.were used mostly to pump natural gas pipelines, using the gas itself as fuel

[PHATR32]

not that it matters, but ive seen a toyota rotory onthe road, never seen one before!

[jase-r34]

Why? So I can read bullshit again?

Yes..... That's why.

[GT-R32]

Yes..... That's why.

Why would he need to read so many posts from someone who thinks a rotary is a two stroke and fails to understand that displacement for any engine is measured using the crankshaft? All that will serve to do is fill someone's mind with misinformation.

[Smity42]

yeah, so I got frustrated last night. Sorry for being a d!ck.

Back in.

First, I will give you 3.9L. No doubt about it, and no way around it, it is a 3.9L engine. So yes, mazda lied there.

However, it is not a 3.9L 2-stroke (which would make it the equivalent of a 7.8L 4-stroke). It is a 3.9L Wankel, the equivalent of a 2.6L 4-stroke. I'm not saying it should be called a 2.6L, it should be called a 3.9L, but it should be considered the equivalent of a 2.6L for motorsport, rego, etc.

Why is it not a 2-stroke? A 2-stroke engine is an engine that requires 2 strokes of the piston to complete the combustion cycle. Likewise a 4-stroke engine is an engine that requires 4 strokes of the piston to complete the combustion cycle. I challenge anyone to find definitions that say otherwise.

sydneykid has been trying to replace the word 'piston' with 'combustion medium' and 'stroke' with 'cycle' and call it a 2-cycle. Well, this isn't right either, the rotor doesnt do 2 cycles to complete the combustion cycle; it does 1. So, what you can do, is create a new class of engine called '1-cycle'. If you define the cycle as one spin of a rotor or one up-down motion of a piston, you can fit both 2-strokes and wankels into this class, but you don't have 2-stroke any more, you have 1-cycle. By this definition, a 4-stroke would be a 2-cycle.

Conversley however, I could create a new class of engine called 'full-cycle' defined by the fact that each face of the combustion medium completes the full combustion cycle. 4-strokes and wankels will fit into this class, but a 2-stroke wouldn't. By this system , a 2-stroke would fit into something like 'half-cycle', defined as an engine where each face of the combustion medium does only half the combustion cycle.

A picture, using set theory, do demonstrate the point I am trying to get across:

Obviously this picture isn't complete, there are many more types of internal combustion engines. This is just the ones we are interested in at the moment.

So, you can't just redefine '2-stroke' to suit your own purposes. A 2-stroke is a 2-stroke, a 4-stroke is a 4-stroke, and a wankel is a wankel. You can make up other names to group engines together, but that is all you can do.

I will give you however, that in many ways a wankel does work similarly to a 2-stroke. I have already said this. But thats as far as you can go. You can't call it a 2-stroke. It's also in some ways similar to a 4-stroke, but again you can't call it a 4-stroke. If mazda did indeed call it a 4 stroke (I can't be bothered reading back to see if that was one of their alleged 'lies'), then yes, that was a 'lie' too.

And you can't apply 2-stroke rules when comparing it to a 4-stroke. This is why it should be compared to a 2.6L 4 stroke, not a 7.8L

This is not a post aimed at sydneykid (who seems very knowledgable), but at anyone still on the 'rotarys are 2-stroke' bandwagon.

As far as the RPM issue goes, I think people will just have to agree to disagree. In my view, they are a 9000rpm motor, even if the rotors are only 3000rpm. 'High-Revving', well thats debatable, it depends on if you look at the engine or the rotors .

Edited September 24, 2009 by Smity42

[GT-R32]

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.

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.

The only technically correct way to rate the engine's displacement is by looking at the shaft. 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. This applies to all engines and from there you have the ability to 'equalise' them as many motorsport bodies have done.

[Smity42]

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