I read a article in sport compact car today that pissed me off! They say the 13B is really a 2.6, and the 3 rotor is really a 3.9!! He said Mazda has been lying to us all!?! This is BULLCRAP!!! I'll state my thoughts quickly and see what everyone else feels. He states the rotary should be doubled because it fires twice as often as a piston engine. If this is true, why dont we Double the displacement on a 2 stroke piston engine? And a single rotor fires 3 times, yes 3 times in 2 crank rotations. Not 2. So going by his rules, I guess we should TRIPPLE the size! Articles like this is why the rotary has a hard time with the public. Write your responses, and reasons, maybe we should all write to Sport Compact Car!!

 

No the 13B is not a 2.6. The Rx8 is a 1.3 ltr, I believe its the same for the 13B.

 

I read that article too. Cannot remember which issue it was, or even what article. It seems to make sence, but I am not concerned with waht ppl call our engines, they put out! Displacement ppl are just pissed off that this is different than theirs and don't understand how simple rotary engines are.

(if you could let me know what issue that was, I'd appreciate it. I wanna go read that article again now!)

 

you really can't compare the two with the same displacement ratings. a 1.3l rotary is equivalent to a 1.3l rotary and a 2.6 liter piston is equivalent to a 2.6 liter piston.

there are good arguments either way on this subject. meh.

 

Yeah !! Exactly!! You cant make our great little power house fit into "piston" spec. Like Apples to strawberries. It is in the newest sport compact out right now. Just hit the newstands yesterday I think in the Ohio area. Its in Technobabble section. I was hopping to get a good response to this question. (although of course I know a 13b is a 1.3 liter). Rather be a rotary than be Pisst.. ON.

 

Correction:

The Rotary engine makes a power stroke per revolution, where as the piston engine makes a power stroke once per every two revolutions. This is why the rotary engine's displacement is doubled.

The number of spark plug firings per revolution is irrelevant. I'm sure we've all seen the triple spark plugged rotaries; They still make one power stroke per revolution... Same as the 4 bangers with eight spark plugs that make one power stroke per two revolutions. (Ford Ranger, and Many Nissans from the mid 1980's. Stanza and 200SX for certain.)

 

you can compare them equally , a rotary works functionally similar to a two stroke and it displaces twice it displacement. It is a 2.6. to say anything else is just ignorant. sure they are not 2 cycle engines i know this. they have four distinct strokes, however the amount of displacement per crank revolution is just like a 2 stroke engine. Get it in your heads ppl!
i know 2 stroke engine displacement designations aren't doubled.
i know no one should change the designation of 1.3L of fury.
that completely ignores the fact that no one drives a 2 stroke car though, and this confuses all the "boinger" ppl.
Fact is it's sad all you "rotary" ppl make fun of us v8 swappers when plenty of you don't know jack about the engine anyway, and the principles it functions upon. Much less that many of us have built rotary engines.

 

These diplacement threads always go on and on with neither camp giving in.

It's true that you can't compare apples to oranges which is why you need to compare the actual amount each engine displaces over one revolution. The working displacement of a 13B is the same as a 2.6litre four stroke engine.

I like to think of the rotary as a four cycle/two stroke engine. It has the four distinct phases of the Otto cycle engine carried out at the rate of a two stroke.

*edit* futant already beat me to it.

 

I agree with Revhed and others, in practice the 13b is a 2.6 litre. Mazda argues its a 1.3 primary for taxation and marketing purposes.

There is no point in pursuing this thread subject, the engineering answer depends on how you specify the question. I prefer mangoes!

 

this is what I was trying to say in so many words.......
It depends on how you specify the question.
1. actual displacement over time(measured by crank rotation for comparison purposes, leaving rpm out of the equation)

2. maker's stated displacement.normally using the guidelines of type of engine. aka two stroke, four stroke, rotary(effectively a two stroke for purpose of this discussion)

Disclaimer: you should already know that the rotary has four distinct strokes (should be called sweeps )they just occur around a rotating rotor so they are kind of happening simultaneously while pumping gases on all sides.

 

futant- I love your off road RX-7. When will we have a description of the modifications?

 

you can't be serious off -road lol.
are you referring to the tractor?

 

oh i didn't even notice that, that's the worst photoshop ever! Oh well still funny

 

Some people just look for excuses when they cant compare.
Why do you drive a Rotary.....why do you drive a Boinger ?

40 cubic inches x2 gives 80 cubic inches...tell me if i`am wrong,but that doesnt ad up to 2600cc.

 

v8

 

ROFLMAO!

Don't know if I'm supposed to be laughing, but I find your signature quite humoring, Jeremy!

I love the rotary, but respect the pistons as well, by the way.

 

https://www.rx7club.com/forum/showth...hreadid=165579

 

Read the article again. It makes sense. Problem is you are trying to compare apples and oranges. Its like comparing the AMD Athlon XP chip to the Intel Pentium 4. Two very different, but very similar beasts. You can't compare straight clock speed or the AMD will get smoked every time. But if you consider how much work gets done for that given clock speed, the AMD beats it.

And SCC can hardly be accused of being unfriendly to the rotary. They have more articles on RX-7's and rotary powered cars than any other car magazine out there that I have seen. Hell, they have had two RX-7 project cars. How many Stratus R/T project cars have they had? None.

Anyways, don't mean to start any trouble, but I fully agree with the article and, when comparing a 13B to a piston engine, I do consider it a 2.6L.

 

When they "car makers" rate the engine horsepower, displacement, fuel consumption, Mazda has a unqiue delmema. What is the max displacement? Since each rotor face can only displace 573cc for 12a and 654cc for a 13b's rotor face, its agreeable that each face can not displace more with out making them wider or larger. So a 1146cc for 12a and 1308cc for a full 13b. Ofcourse they are not a 4stroke or 2stroke cycle, they are a rotary cycle, league of their own.

It has both in common with 4 and 2stroke, but are not the same. What would be the most undeseiving way to rate a rotary engine/2stoke/4stroke engines? The answer would be to rate its fuel consumption per unit time at a speific rpm and throttle position, and its output. Ofcourse this varies from engine to engine, what modification or flow ability it has, etc. No perfect way to determine.

 

2.6, 1.3 whatever its still somthing different from the norm which is why I for one will always like the rotary engine

 

As everyone says, its a matter of convention, and in no way affects the output of the engine. So whats the problem? I can see the bragging rights that come along with the engine, at least in terms of specific output when you rate it 1.3L.

 

Why is this so difficult? It sounds like a bunch of Stats profs arguing numbers.

What is the volume of the chamber? What is the volume of the rotor. Chamber-rotor=displacement. Or, volume capable of producing power at some point. Likewise a boinger has a static volume as each piston moves up and down at a set rate.

How we use the available volume seems to be at question.

Is the volume of a 13b 2.6 litres using this method?

 

i was feeling left out since i don't have any real mods besides some nawz stickers.

this argument comes up about as often as the octane and atf threads. to me i don't care about displacement. the important factors that can be compared for every motor is peak hp and torque, powerband, weight, and gas mileage. maybe the octane needed to guess any power vs money ratios. as two cars can have 28mpg but one is more expensive 28mpg since it needs premium. displacement argument is for hondas to try and feel cool and v8 owners to sport their big heads.

 

A 2.6l boinger only wishes it could be a rotary! hehehe

 

WTF are you talking about?