The official piston equivalent size is...
 

2616cc's to be exact, also taken from the same book as the weight. So much for the argument now. So if you think about it that's also the size of the 4 rotor engine...so the 4 rotor would be 5232cc's...the 3 rotor 3924cc's, and can't forget the 6 rotor at a whopping 7848cc's!:)

6 rotor?

1.3l is the measure of the compression stroke volume. Same for a iston engine. The 2.6l you got is measuring the compression and the exhaust stroke seperatly.

Measure a normal engine like that and you've got a 10 liter mustang.

No, that's wrong. A rotary engine has twice as many intake strokes per revolution as a piston engine, so in theory a 13B can breath twice as much air as a piston engine of the same 1308cc capacity. This is why 2612cc is used as a piston equivalent, because it more accurately reflects the engines breathing ability.
In reality, the rotary's VE isn't quite as high as a piston engine, so is dosn't actually breath twice as much air. That's why most racing formulas use an equivalency factor of 1.8 instead of 2.0, to give 13B's a capcity of 2354cc and 20B's a capacity of 3532cc.
Just for interest, a factor of 1.4 is often used for turbocharged engine in racing, meaning a 13BT would be classed as 3296cc.

Very true NZ...very true, but that's what Mazda officially says so that's what I felt like posting. Something "concrete" so people stop asking, instead of the many ways a rulebook can be read.

but using your therory, a 1L 2 stroke would be classed as a 2L. but it's not. it's a 1L 2 strock... which is why a rotary is a 1.3L rotary.. and not classed with pistons...

My question: Is the 1.3L from one or two revs of the shaft?

All I know for sure is, we get two power strokes each revolution.

Stroke is refering to the piston going up and down.. A rotor kinda spins it cant be described as a 2 stroke or a 4 stroke. Its a damn rotary mazda surely found that its 1.3L are you calling them liars...
How can you consider it a 2 stroke or a 4 stroke anyways? If it doesnt stroke?

A rotary engine has one power cycle for every one rotation of the e-shaft, per rotor. A piston engine has one power cycle for every *TWO* crankshaft rotations, per piston.

The rotary power cycle also has a duration of 270 degrees of e-shaft spin, while a piston engine's power cycle lasts for 90 degrees. This helps make it smoother, since the power is "on" more of the time. It's "on" all of the time, since the two 270-degree cycles (two rotors, remember) overlap.

Using this crazy information, you can call a rotary pretty much anything. observe:

A rotary is like a 2-cylinder! It has two rotors. Maybe a 2-cycle 2-cylinder.

A rotary is like a 4-cylinder! It has 4 spark plugs, and has two power pulses per revolution!

A rotary is like a 6-cylider! It has 6 combustion chambers! Maybe a v-6, since it's "split" into two "banks" of three chambers..... :)

A rotary is like a *12* cylinder! With 270 degrees of duration x 2 rotors, power is always on (2x270=540).. A 12-cylinder has 90 degrees of power, x 12 cylinders, x 1/2 being in the power cycle....=540... (ok, that's not exactly "math"... heheh)

How about, a rotary is it's own thing.

-Tesla

heh... tesla good call.. key phrase being "a rotary is like..." ;) but like you say it all comes down to a rotary is a rotary.. It doesnt have strokes it has cycles... lol

all's I know is this..

a piston engine goes:
1) Intake
2) Compression
3) Power
4) Exhaust

a rotary engine goes:
1) Power
2) Power
3) Power
4) Power
5) Power
6) Power
7) Power
8) Power
9) Power

get the point?

It's not a theory, it's the method generally used in the motoring industry and motoring media to compare rotary engines to 4-stroke piston engines. Only Mazda calls the 13B a 1.3L engine. In motoring media and motor racing rotaries are classed with piston engines, so an reasonably accurate method of comparing them has to be used. It would be pretty stupid for a 13B-powered race car to be classed as 1.3L, because in power terms it obviously isn't... ;)

Does it really matter anyway?

You know what is the best part about a rotarie?

All those DSM guys that go around beating mustangs going "its just a 4 banger and you got beat!"

Well now we can beat DSM owners and say "ahahah you got beat by a 1.3L"

:D

That's right, this IS NOT a theory that I made up. It's what Mazda themselves have said. No matter how you want to look at it, they made it so they're right. :D

Well i dont care what the hell the displacement is all i know is i love my Rotary Engine:D

1.3 litres is 1.3 litres, no matter if you make power every stroke or every other stroke or every three strokes. It is very difficult to say what a rotary engine is equivilant to in the piston world. Although it has been tried in racing circles, but that formula has changed many times(so that a rotary won't win). A two-stroke 500cc engine makes less power than a 1000cc 4-stroke engine. The same would hold true for a 1.3l rotary vs. a 2.6l 4-stroker.

took it right out of my mouth

it is its own thing. but have to be catorgorized when competing with other engines. i just like the power power power thing!! hehe

I also agree the rotary is it's own thing (and the greatest thing I might add ;)), but I'm just stating what Mazda publicly says. That's all...it's just here to end that stupid argument of what people THINK it is and what Mazda SAYS it is.

You've sorta contradicted yourself there. If it's so difficult (and you're right, it is), a 1.3L rotary obviously isn't 1.3L... ;) Not entirely true. Assuming a 2.6L nominal capacity, 62hp/L was pretty respectable for a quiet, emissions-complient engine in 1989 (160hp S5 NA), and 96hp/L (250hp RX-8) from an NA is better than all but a few production NA 4-stroke piston engines.

What do you mean? You do realize that there is more than one type of piston engine, right?

... and your reference is? All of my Mazda media lists a 13B as 1308cc.

Read the book "RX7" by Jack K. Yamaguchi it was made in late 1985 to accompany the '86 FC. On page 80 in the Engine section it says...

"Total cubic capacity equivalent to reciprocating piston engine, cc...2616"

It list basically every single stat for the car (including the weight of 2625,2695,and 2715)

The book also has information on every rotary engine up to that date, and all the cars that did and DIDN'T make it (like the 21A engine and a few cool projects like the first MX-03). You really should read it, if not just look at the UNBELIEVEABLE photography! I think a picture isn't worth a thousand words...because when I look at these I can't say a single word...

And where do you get the idea that the Yamaguchi book is the Official Word of Mazda? It's not - it's a book written by a third party. And you're not even reading the latest edition of the book.

SAE (the Society of Automotive Engineers) is the body to turn to - not some book you've found that "claims" a bunch of stats. Displacement is defined by the swept volume of one power-producing cylinder multiplied the number of cylinders. A Mazda rotary displaces 1308cc, and nothing more. How it uses that displacement is a different story.

:rant:

Brandon

I think he was referring to a 4-stroke Otto cycle piston engine to make it easier for the masses to understand. The comparison doesn't work with a 2-stroke Otto cycle, or 2 or 4-stroke Miller cycle, and it gets more confusing with the push-pull piston engines like the Lenoir and Dyna-cam, even though they are also "piston engines".

I think that you don't understand the context of the book. Like the previous post states, SAE is the international authority for such definitions.