First of all, I've searched for the answer to this but no luck. Posting is always my last resort, so bug off flamers!

Alright, I'm just curious as to what the letter means in a rotary engine's name (e.g. 12A, 13B). I know the numbers refer to the displacement, but what the letter means has been bugging me.

Thanks!

 

those A B C D E F J stands for generation.

Renesis is 13B-MSP

Older RX-7 (FD) engine is called 13B-REW

and so on.

 

Well that's not true .....

My Renesis name is Betsy.

 

B for Bella.

 

My Renesis name is Renesis :-P

 

I guess mine is "Baby" because I'm always yelling "Yeah, Baby!"

 

You named your car after one of my bunnies???

 

Did I?

 

10A - 12A - 13A

Are all A-series engines from pre-1974

12B - 13B

Are all B-series engines from post 1974.

The 12B was still stamped a 12A for marketing reasons but Mazda insiders refer to is as a 12B. Much the same way the 13B-MSP is reffered to as a Renesis to catch people into the trendy marketing.

Here are other rotary engine (actual) names from over the years.

12A-AP (anti pollution)
S12 Capella (RX-2) + S12 Savanna (RX-3) + LA2 Luce (RX-4) + LA4 Luce + CD Cosmo (RX-5) + SA Savanna (RX-7)

13B-AP (anti pollution)
LA2 Luce (RX-4) + LA4 Luce + CD Cosmo (RX-5)

12A-SPI (six port induction)
HB Cosmo + SA RX-7

12A-turbo (turbo)
HB Cosmo+ SA RX-7

13B-RESI (rotary engine super injection)
HB Cosmo + FB RX-7

13B-TII (turbo twin scroll)
HC Luce + FC RX-7

13B-REW (rotary engine double turbo)
JC Cosmo + FD RX-7

20B-REW (rotary engine double turbo)
JC Cosmo

13B-MSP (multi side port)
FE RX-8

REgards

 

werent the 13b-RESI used in the S4-S5 n/a FC's too?

 

Alright that makes sense. Thanks

 

Why do you say FE RX-8 when it is reffered to as SE? What's the difference here?

 

Well FE is the Chassis code. You'll see it all over the place on the car if you look close enough. SE is (correct me if I'm wrong) a trim level in some countries like Sport or Grand Touring in the USA.

 

no... se is from SE3P.

 

wrong... chassis code is SE3P and body Code is FE... as opposed to SA22,FB3S,FC3S,FD3S. its an RX8... not a rx7.

 

the B represents the internal geometry of the engine, the epithrochoid shape, the eccentricity, and such

It's mentioned in the Yamaguchi RX-7 book, don't know if it's in the RX-8 book as well.

That's why even though the Renesis design is very different it's still a 13B beacuse the internal geometries are the same.

 

You're right, brain fart.

 

neit_jnf has it as I also understand. More is that I remember that all engines in Japan must be registered with the government. The 10A & 12A were the original geometry when registered. 10 is 1.0 liter, 12 is 1.2 liter. When the 13B, 1.3 Liter, came out and registered the 12A was also changed in geometry, but still officially called the 12A as that was what was registered. Many called it the 12B, but that was not the official designation.

 

Wait wait wait. What about the 13G? And..the FC NA engine was the 13B-FI...fuel injected...

And...I know of the FC Turbo engine being labeled the 13B-T, not TII. The S5 Turbo didn't even have a twin-scroll, so I don't understand this.

 

It's not called Turbo II because it was twin scrolled. It is the second turbo model produced, the first turbo model was Japan only.