teencraft

yo how do you tell the sizes of the motor (like 12a, 13a, 13b etc...) is it in the GS or GSL or what? and what would an early 80's be? thanks alot, sorry i'm so "uninformed"

diablone

iTrader: (2)

GSL-SE is the only one with a 13B, the rest are 12A.

rotary emotions

roughly said the number in the engine name is the "size". Like 10A = 1.0 liters, 12A = 1.2 liters etc.
This isn't completely correct, since 1146cc isn't really 1.2 liters, of course. Keep in mind this is purely the mathematic size of the engine, as used by NSU and later Mazda to identify engine capacity.
Due to the way the Wankel works, most people will claim it's a 2.3 (12A) or 2.6 (13B). There's some discussion about that, and I don't want to start that all over, so I just mention the size as NSU (the first Wankel/rotary builder) saw it.

teencraft

k thx both of you,
few more questions,

what is the biggest and smallest engine? also what does A and B stand for?

smnc

Check Feliz Miata's Site
http://members.ij.net/mrmazda/cfaqtext.html#10A12A13B

The_7

smallest i believe is a 10A. i dont think there are too many of those. next biggest is 12A, then 13B. 12A and 13B are the most common engines. the 20B is a 2 liter 3 rotor which is rare and expensive but you can get your hands on one if youve got money. lastly there is the 26B 2.6 liter 4 rotor that mazda made for their lemans racecar ( ), but you wont get one of those .

chairchild

Like my insurance company

teencraft

what type is the GSL?

diablone

iTrader: (2)

12a

rotary emotions

A and B are versions/improvements. Same capacity, but different engine. There was a 13A, used in very few cars. The 13B soon came after that. Some say the A and B mean different excentricity of the E-shaft, but I can't confim that (nor deny, I simply don't know )

smnc

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.

teencraft

so the B means two rotary engines?

Scruch

my old 12a have 2 rotors too... ! b and a whats mean?

smnc

Okay listen up, because I'm only going to spell this out once.

There are 2 main measurements that effect a rotary's performance (besides rotor size/displacement). They are called Eccentricity and Generating Radius, but that's not important.

Mazda made the 12A with two 573cc Rotors (1146cc or approx 1.2 litres total), an eccentricity of 15mm and generating raduis of 104mm, which are the same numbers they had used in the 10A. Since it was the first 1.2 litre engine it was called the 12A

While working on the next generation engine they increased the rotors to 654cc (1308cc or 1.3litres total) and changed the eccenticity and generating raduis to 17.5 mm 119 mm. As the first 1.3 litre engine it was called the 13A.

After a VERY limited production run, Mazda found that the original eccenticity and generating raduis from the 12A was much superior.
They then created a new engine using the same 654cc rotors, but the original eccentricty and generating raduis from the 12A and 10A. Since it was the SECOND 1.3 litre engine produced, they called it 13B

Got it?

REVHED

Thanks for the info. Never heard that before. So how does the 13G fit into all this?

karism

From what i know the 13G was a 3 rotor peripheral,dry sump,efi engine ?

It was also developed before the 20B came out (race only)

Pedestrian X

what about the 787B, or was that just the name of th car?

diabolical1

iTrader: (3)

yeah ... this is the first i'm hearing about this also. i always thought that A and B dealt with the types of seals that Mazda used in the engines ...

and yes ... i've always questioned the 13G and 13J engines - which go against all previous nomenclature protocols.

Karism -
i'd read the exact opposite. i read that the 13G was race version of the 20B, but since there was no street-version of the 26B, i don't know what the 13J represented ... ?????

and PedestrianX -
yes, as far as i know 787B is just their LeMans car

Rotortuner

The 4 rotor that was in the 787b i believe has been called the R26B is several places. As for the 13g engine, you have got me. Its just an early race engine that is essentialy a 20b,, befor they started to mass produce the 20b's.

CJG

kettlman

iTrader: (2)

DAMN. I'M ALMOST CONFUSED. i do remember though, when they got that 13g with the 3 kkk turbos goin on the salt flats. how fast did it actually get to? i know it was over 300. and don't forget the single rotors that went in motorcycles?


http://www.monito.com/wankel/engines.html

Rotortuner

If your talking about the Racing beat cars, the 2nd gen did 238 and the 3rd gen did 242.

CJG

FB II

i dont think he's talking about the racing beat ones

karism

Sorry,i was explaining like my rear side again.

I meant :The 13G was the race only,dry sump peripheral ported 3 rotor. Before the 20B was mass produced in the Cosmo.

I think i got it right this time....

Its time for some Prozac and Beer...i need to wake up :-)