Why Do Rotaries Suck?

[Sydneykid]

Because your comparing a piston engine again. Each piston makes one combustion per cylinder where a rotory makes 3 per rotor.

You're comparing a cylinder with a rotary chamber. When the truth is they are nothing alike, physically or dynamically.

A piston in that cylinder has only one combustion face, a rotor has 3 combustion faces.

Cheers

Gary

[DRD-00F]

Here's a joke for everyone to lighten the mood :

A man walks into a pub. There are three blokes at the bar talking racing, and being partial to such things, he decides to have a chat. Bloke 1 races bikes, bloke 2 race piston cars and bloke 3 races rotary cars.

They get to talking about what they race and the man asks each of them a simple question:

"What's your engines displacement?"

First bloke says "1000cc"

Second bloke says "2.6L"

Third bloke says "Define displacement..."

lol. Don't shoot me.

[nisskid]

[GT-R32]

People shouldn't take direct aim at Mazda for this. NSU rated their engines the same way, the rotary being under licence from them. I would expect it came back to Felix Wankel also.

The mathematics of exactly why 1.8 times was chosen, instead of say 1.9 or 1.7 or leaving it at 2, no I don't know. It was a bit of a closed shop back then, that secret boys club stuff is why there was a big spill in the CAMS board, new president etc.

I don't recall an official communication on it, there was some discussion that it may have been pushed due to improvemetns in piston engine efficiency in the previous 25 years compared to virtuallty static rotary rotary efficiency. If we knew that for a fact, which we don't, then a counter argument could be made based on Renesis development. In simple terms, there has been rotary development, put it back to 2 times.

Personally 1.8 or 2.0 is irrlevant as it is simply a multiplier of a number that is incorrect anyway. ie; 2.0 X wrong = wrong.

Never expressed it as 0.59, let me check, 1.3 x 1.8 = 2.35 / 3.9 = 0.59.

Yep, the maths works, but I have idea what 0.59 means.

Is there some signifiicance to 0.59?

I know that it was reduced from 2 times in the mid 90's, I can't remember the exact year, I'd have to check my CAMS Manuals. Different food chain back then. I know that it's now 1.8 times, but only in Australia, it is different elsewhere. A turbo petrol engine is 1.7 times and a turbo diesel will be 1.5 times when CAMS approves my recommendation on it.

Cheers

Gary

So, you don't know what x2 or x1.8 or x0.59 (this one is for you) means, or where it comes from? One can only assume this is because you don't understand the time relative derived by the shaft where horsepower and torque are measured. Is that correct?

[Smity42]

Here's a joke for everyone to lighten the mood :

A man walks into a pub. There are three blokes at the bar talking racing, and being partial to such things, he decides to have a chat. Bloke 1 races bikes, bloke 2 race piston cars and bloke 3 races rotary cars.

They get to talking about what they race and the man asks each of them a simple question:

"What's your engines displacement?"

First bloke says "1000cc"

Second bloke says "2.6L"

Third bloke says "Define displacement..."

lol. Don't shoot me.

I lol'd

[Jez13]

You're comparing a cylinder with a rotary chamber. When the truth is they are nothing alike, physically or dynamically.

A piston in that cylinder has only one combustion face, a rotor has 3 combustion faces.

Cheers

Gary

Weren't you the one who was comparing a 6 cylinder piston engine with a rotory? And now you say you can't compare because they are completely different which was my whole point from the start...

Another way to visualise my perspective is to try and imagine that the rotor is just one giant angled face instead of breaking it down into 3 faces (or 3 cylinders in your mind). And that would make you understand that one rotor combusts 3 times in a cycle and turns the crank/e-shaft 3 times with it. Thus producing 1.3l per crank shaft cycle and combustion cycle. If a piston where to do that it would intake 3.9l of air but only use 1.3L of air per cycle (its impossible to do but its for perspective purposes only).

[Birds]

To me it's black and white, a rotary is a combustion engine, Otto cycle if you prefer. All other combustion engines, every single one of them, are measured the same way. Piston port, 2 stroke, 4 stroke, diesel, petrol, 2 valves, 4 valves, 5 valves, pushrod, SOHC, DOHC etc etc they are all measured exactly the same way. Regardless of efficiency or number of revolutions of the crank/eccentric shaft. There is only one that isn't and that's wrong.

You say Mazda should be allowed to get away with it becuase they say its "1.3 litre rotary engine", the "rotary" qualifier means they can use whatever measuring stick they like. But if anyone else tried the "1.3 litre 4 stroke" or "1.8 litre diesel" when it was really a 2.6 litre you'd be screaming blue murder.

You say it's OK to understate the engine's true capacity by a factor of 3, because everyone knows its really a 3.9 litre. When the truth is not everyone knows, this thread is living proof of that. If everyone knew then it would have stopped at page 1.

I have plenty more ways of explaining why 1.3 litres is wrong, using any termninology you care to dream up. You can muddy the water all you like, I know what the bottom of the river looks like and I can clear it up so everyone else can see it too.

The problem with your examples there, no matter how varied the engine they are all piston engines...quite rightly measured the same way as each other.

Yes I say they should get away with it because the "rotary qualifier" indeed means they can use their own measurement...as long as it is consistent with our knowledge of how rotary engines work, and as long as it is consistent with every rotary engine they've ever produced and classified. And guess what? It is! Not a lie. They're the only car manufacturer doing rotaries, they get the say of how their engine is measured. Of course we'd scream blue murder about a 2.6 litre 4 stroke classed as a 1.3 litre...there are hundreds of manufacturers who already use the same method for measuring displacement in a piston engine. It's already carved in stone...so to differ from this knowledge is a lie. Mazda on the other hand, had a fresh slate with the rotary...and safe to say, we will forever be measuring rotary displacement based on Mazda's method simply because they pioneered the rotary engine in mainstream automobiles. Their method has been cemented in history and you can't/won't change that. They owned the rotary game, they made the rules for them. We adapt to this rule with our comparisons and formulas and that's all that matters. Just like we adapt to 4 strokes and 2 strokes being different so we have formulas for them too.

What if you have NO knowledge of a rotary (believe it or not birds, this is most of the world)? What if Mazda DID already compare this engine/car combo with existing piston engined cars?

It's, at best, tricky, underhanded advertising, and at worst, a lie.

SHOES SHOES SHOES! BUY TWO, GET ONE FREE!

Would you expect to walk out of the store with 3 shoes, or 3 pairs?

Mazda aren't stupid, they knew exactly what they were doing, and I for one, don't agree with those tactics.

Most of the world doesn't know how an internal combustion engine works let alone a rotary. So is a manufacturer therefore deceiving their customer, just by selling them something that they don't know the workings of? Because I'm pretty sure that would be a conservative 95% of the market/population who buy cars. If a manufacturer claims their 2 litre turbocharged engine can offer the performance of a V8, without explaining the turbocharging process, and manfacturers do this all the time...are they lying too? I've known since I was a kid that Mazda's 1.3 litre rotary is not fair comparison for a 1.3 litre piston engine. It's not that hard to understand if you actually care about the displacement. Show me where, in this advertisement you've linked me, Mazda claim their engine to be (or even equivalent to) a 1.3 litre piston engine. All they've done as far as comparison is the inputs and outputs of the engine...in the context of the vehicle I might add...i.e. fuel economy and performance...quite valid. They even state in that ad that it is a rotary engine...to which we, the unknowing consumer ask...what is a rotary engine? Well instead of cylinders it has a three faced rotor with 3 combustion chambers but only one of them fires at once, it's not the same as a piston engine so don't go thinking that it is the same blah blah blah.

Welcome to the world of marketing mate...I'm not saying Mazda didn't acknowledge the advantages of calling this engine a 1.3 litre engine over calling it a 3.9 litre...I just think they've done it quite rightly. Do you think there is a manufacturer of anything in the world, who would spend money on portraying their product in a negative light?

[bigmikespec]

Can people start condensing their posts to like a few lines... f**k I can not be assed reading that much.

Birds you type too much bro

[Birds]

Mine are as concise as they can be...you would hate to see the thesis I could put out on my points. There's alot of shit that has to be written so people know exactly what I'm talking about and I leave nothing open to interpretation...otherwise people develop a habit of twisting my words into meaning something else.

Short answer, no.

[DRD-00F]

No, those selling piston engines aren't deceiving anyone, cause the benchmarks for 1.3L or 2.0L or 5.7L are already set, and real world equivalancies have been made and are set IN STONE, just like you said. Mazda had NO CHOICE but to sell this against 4 stroke engines, as there was no other existing engine for cars. So the comparison is already there, wether mazda like it or not, and then they started going on about how good the fuel consumption is... compared to...? 4 stroke engines! Completely ignore the fact that it directly states the Datsun 240ZX or Porsche 924, both of which have 4 stroke piston engines... that's cool

I know the world of marketing quite well, which is why I don't agree with what they've done. They've caused problems all across the board, with CAMS, different racing classes, officials and now this 35 page thread on a Skyline forum.

Fact is, if you want to stay out of trouble in marketing, you use the most basic and obvious information, and cater for the lowest common denominator. You on the other hand seem to think it's fine that they sell a car with an engine that 95% of the population hasn't heard of, and just ASSUME that people know all the tricks about the engine.

[mad082]

Here's a joke for everyone to lighten the mood :

A man walks into a pub. There are three blokes at the bar talking racing, and being partial to such things, he decides to have a chat. Bloke 1 races bikes, bloke 2 race piston cars and bloke 3 races rotary cars.

They get to talking about what they race and the man asks each of them a simple question:

"What's your engines displacement?"

First bloke says "1000cc"

Second bloke says "2.6L"

Third bloke says "Define displacement..."

lol. Don't shoot me.

I lol'd

so did i

[Birds]

No, those selling piston engines aren't deceiving anyone, cause the benchmarks for 1.3L or 2.0L or 5.7L are already set, and real world equivalancies have been made and are set IN STONE, just like you said. Mazda had NO CHOICE but to sell this against 4 stroke engines, as there was no other existing engine for cars. So the comparison is already there, wether mazda like it or not, and then they started going on about how good the fuel consumption is... compared to...? 4 stroke engines! Completely ignore the fact that it directly states the Datsun 240ZX or Porsche 924, both of which have 4 stroke piston engines... that's cool

I know the world of marketing quite well, which is why I don't agree with what they've done. They've caused problems all across the board, with CAMS, different racing classes, officials and now this 35 page thread on a Skyline forum.

Fact is, if you want to stay out of trouble in marketing, you use the most basic and obvious information, and cater for the lowest common denominator. You on the other hand seem to think it's fine that they sell a car with an engine that 95% of the population hasn't heard of, and just ASSUME that people know all the tricks about the engine.

I'm not seeing your point Doof. I didn't ignore the comparison at all. There's nothing wrong with comparing a rotary powered car to a piston powered car and I never said there was. In that advertisement Mazda are comparing inputs and outputs of the vehicles which is quite reasonable. They've even stated their engine in the car is a rotary. They can brag about fuel consumption all they like...they've stated the consumption figures for it, so it's even a subjective call for you to make up your own mind based on them? What more do you want from Mazda? That is actually one of the most legitimate pieces of advertising I've seen from a car manufacturer. They've specified the cars/market they're targeting, they've given some key statistics which matter to a consumer and they've even included the price of the thing. No deceptive mention of the engine being anything like a 4 stroke or the same displacement as a 4 stroke. In contrast, there is something seriously wrong with comparing the internal combustion process of a rotary engine to a piston engine because you will get nowhere fast, just like this thread.

Why should Mazda give a shit about people arguing over displacement for homologation purposes? They're a car manufacturer, their primary concern is sales, not motosport. No issues as far as the RX7 goes; I would like to know how many customers who bought an RX7 or any other rotary powered vehicle, took it up with Mazda that they got ripped off when buying their car because they thought the thing had the equivalent of the same displacement 4 stroke piston engine in it. Where are the class actions taken up with Mazda over this? You guys are just kidding yourselves over nothing...take a step back from the pedantic argument that's been kicked up here and look at the real effects this 1.3 litre / 3.9 litre business has had on real life. Outside of motorsport, for which we already have our formulas to fairly compare piston powered vehicles with rotary powered vehicles, it is absolutely nothing. Deal with it.

Once again, do you think its fine that manufacturers don't explain how the turbocharging process works? Because I guarantee like the rotary, atleast 95% of the market don't know how turbocharging works. Yet they'll be deceived by the assumption that their 2 litre engine will give them the economy of a naturally aspirated 2 litre and that there are no tricks to getting all this extra power. And you think Mazda are the only ones running double standards by choosing how they market their UNIQUE engine? Come off it.

[DRD-00F]

Outside of motorsport, for which we already have our formulas to fairly compare piston powered vehicles with rotary powered vehicles, it is absolutely nothing. Deal with it.

So, outside of motorsport, without these formulas, the comparison is unfair?

[Birds]

Outside of motorsport, without these formulas, the comparison of displacement between a rotary and a piston engine is irrelevant. All that matters are the inputs and outputs, e.g. what the car can do and what it costs.

[DRD-00F]

Outside of motorsport, without these formulas, the comparison of displacement between a rotary and a piston engine is irrelevant. All that matters is what the cars can do and what they cost.

That's not what you said. You said it was unfair.

It's very relevant. It's a buyers market, and people are comparing every aspect of every car they might choose. Are they not?

Lets head over to car sales and see how people are advertising their cars:

2007 PORSCHE 911 997 MY07 TURBO AWD

2dr 4 seats COUPE 6cyl 3.6L Semi-Automatic 9,000 kms

2009 AUDI A5 8T MY09 S-TRONIC QUATTRO

2dr 4 seats COUPE 4cyl 2.0L Sequential Manual Auto-Dual Clutch 10 kms

2007 BMW 325i E93 MY08 STEPTRONIC

2dr 4 seats CONVERTIBLE 6cyl 2.5L Semi-Automatic 32,600 kms

2009 TOYOTA PRIUS ZVW30R I-TECH

5dr 5 seats LIFTBACK 4cyl 1.8L Constantly Variable 1,399 kms

2008 MERCEDES B200 W245 MY08 TURBO

5dr 5 seats HATCHBACK 4cyl 2.0L Constantly Variable 23,000 kms

Oh well f**k my arse! They all seem to have the literage stated! That's interesting seeing how it's irrelevant. And how stupid of them to not add their quarter mile times and winton lap times... tisk tisk tisk...

Now let's check out some RX7s, cause they look cool, I might buy one of those...

2000 MAZDA RX-7 FD

2dr 2 seats COUPE 2cyl 1.3L Manual 30,117 kms

2000 MAZDA RX-7 FD Spirit R Type B

2dr 4 seats COUPE 2cyl 1.3L Manual 50,000 kms

2000 MAZDA RX-7 FD

2dr 2 seats COUPE 2cyl 1.3L Manual 71,600 kms

Oh well shit, even the rotary people are stating literage! If only they knew that it was irrelevant and they will sell their car much faster if they stated how many chicks it could pull...

I spose if I wanted to compare these cars in my choice of buying one, I couldn't... well that sucks. I wish every car was advertised with a drag time or engine power, then I could compare, but alas, both of those have too many variables and are often different between each car.

Wether YOU want to face it or not, the comparison is already there, in black and white. It's not irrelevant, it's not the best way to do it either but that's how the general public do it. You're asking every person in the world to completely understand an engine before buying it as the information stated is unfair in comparison to other cars they might be purchashing. That's the reason we have stats, that's the reason we have foot notes, that's the reason we have blurbs, or reviews, or previews, so you don't have to know absolutely everything about it to make a decision. Well what if the information in that blurb/review was innaccurate? You would want everyone to suck it up and just to have KNOWN what was going on before even reading the blurb/review. That's a bit mean innit?

Also, it seems carsales.com is stupid for not adding a rotary option...

[Jez13]

That's not what you said. You said it was unfair.

It's very relevant. It's a buyers market, and people are comparing every aspect of every car they might choose. Are they not?

But what if, in Mazda's view that 1.3L is the truth. What if all those highly intelligent engineers that create our Japanese cars came to the conclusion that a 13B rotory is in fact a 1.3l engine. If that is the conclusion then nobody is lying or deceiving. I can understand why it is a 1.3L and connot be a 3.9L - not my fault that others can't.

[DRD-00F]

I'm not bending rules or views to see why it could be a 1.3L. I'm not saying it cannot be this or that.

I'm simply using the same methods used to calculate literage on every other engine to see what it comes out at.

[Jez13]

I'm not bending rules or views to see why it could be a 1.3L. I'm not saying it cannot be this or that.

I'm simply using the same methods used to calculate literage on every other engine to see what it comes out at.

Yeah, every other piston engine.

[DRD-00F]

Rotary engine is still an engine.

[Jez13]

Yes it is, but you can't use piston formulas on it to decipher its capacity.