sTaLa

Just wondered. Thanks guys.

synesthete

LOL.

Thats what the engine is called 13B, does it have to mean something....
The one rotor first gens were 12A, so there you go... B = 2 wankels

Juiceh

iTrader: (4)

Please tell me your kidding.... If not, you have no right to laugh at the original poster.

12A is a 2 rotor....

StealthFox

iTrader: (2)

...not only that, if the letters meant how many rotors it has, why is the cosmo's 3 rotor engine called the 20b?

13b4me

Yea wtf lol?

Cosmo_TT

iTrader: (11)

damn a one rotor would be hella slow talk about no power lol

TonyD89

iTrader: (10)

Sorta what was said above. The displacement went up to 1.3 liters from 1.2 in the 12A. Basically by widening the rotors. Therefore making a different motor.

13b4me

Actually the 12A was a 1.1 liter engine...

sTaLa

12A --> 2 rotors, 1.2 liters (If I remember well)
13B --> 2 rotors, 1.3 liters
20B --> 3 rotors, 2 liters
The T is for turbo, I just thought that B meant someting, and it must. They don't just decide anything without any sense behind it.
Maybe it is for 2nd gen, but if it is so, there would be a C with the 3rd gen no?

playdeadva

the b is probably just because its the 2nd rotary engine in rx7s. and 20b is still b probably coz each rotor still has the same displacement. maybe when a new motor comes out with each rotor displacing more it will be C??
just taking a guess.

Juiceh

iTrader: (4)

Just a thought, B could be like a revision number. For example, maybe after the 12A mazda made a 13A prototype that never saw production, then upon making a few changes they renamed it the 13B.

*edit*
IIRC there was a thread about this a while back and I think the letters had to do with rotor width.

sTaLa

Yeah my idea is that the letter is for the kind of rotor. But rotors from the FCs and FDs are different no? And there's no C with FDs' engines' names...

playdeadva

i think fds have lighter rotors but they have same displacement??

TonyD89

iTrader: (10)

Is it a rounding thing? Like 1.15. Up or down? In math, it's up.

13b4me

The FC and S5 TII have the same rotors... And yea I think it's a rounding thing, although it's classified as a 1.1L in the parts fiche, and anywhere else I've seen it...

synesthete

Somebody told me they were 1 wankel, i never questioned it guess i shouldnt believe that guy. I've never even looked under the hood of a 1st gen....

sTaLa

I know they made some 12 A with only 1 rotor, and also 13 b I think. But they were more used with aircraft I think so. I read it in the 1st gen section. I'll try to find the post.

sTaLa

I found the post. There's nothing about a single rotor 13b. The guy only wondered if the single 12A was not a half 13B.
Here's the link: https://www.rx7club.com/showthread.p...ighlight=rotor

Icemark

The A or B or etc refers to the rotor width.

There are 10A and 12B motors as well as 20B and G, and 13A models. There was even J models.

70mm width = A
80mm width = B

etc

13b4me

There was never a 12A or 13B single rotor engine... And Icemark, lest we forget the 13G?

neofreak

from the faq:

What do the 10A, 12A, 13B & 20B Mazda engine designations mean?


The numbers represent metric displacement. Power is generated from one face of each rotor per shaft revolution. 10 is the result of two 491 cc rotor chambers, 982 cc total, which rounds to 1.0 litres. 12 is the result of two 573 cc rotor chambers, 1146 cc total, which incorrectly rounds to 1.2 litres. 13 is the result of two 654 cc rotor chambers, 1308 cc total, which rounds to 1.3 litres. 20 is the result of three 654 cc rotor chambers, 1962 cc total, which rounds to 2.0 litres.

The letters "A" & "B" represent the combination of two basic production engine configuration parameters, "eccentricity" and "generating radius". The "A" is applied to the first (A), and only, combination of the two specifications actually deployed in a regular production engine of nominal 0.60 litre displacement per rotor, the 12A. The "A" was also applied to the first (A), and not only, combination of the two specifications actually deployed in a regular production engine of nominal 0.65 litre displacement per rotor, the low production 13A. Mazda later determined greater economy could be achieved by using the 12A's combination of eccentricity and generating radius in conjuction with a wider rotor, thus giving birth to the second (B) regular production rotary of nominal 0.65 litre displacement per rotor, the 13B. If Mazda were to create new two rotor engines of 0.60 and/or 0.65 litre displacement per rotor using some different combination of generating radius and eccentricity, application of the same logic previously applied by Mazda in naming its rotaries would give birth to a 12B and/or a 13C.
Engine Eccentricity Generating Radius
10A, 12A, 13B, 20B 15 mm 104 mm
13A 17.5 mm 119 mm

Eccentricity
the distance from the center of eccentric shaft rotation to the center of the rotor
Generating radius
the distance from the center of the rotor to its apex.

TonyD89

iTrader: (10)

Bam! I guess were done!

sTaLa

Thanks Neofreak, that helps a lot.

StealthFox

iTrader: (2)

that settles it, goes to show you need to read the FAQ before posting

KeloidJonesJr.

iTrader: (8)

What does the RX-8 come with?