Was talking about rotaries today and realized I have no idea what the B stands for on rotary engines. I know x is used to designate experimental (16x) and there have been A, G, and J versions of the engine. Wikipedia has some great reference pages for both the Wankle and Mazda specific rotaries and will let you trace the engine and different designations but doesn't note what they mean.

http://en.wikipedia.org/wiki/Mazda_Wankel_engine

So either they don't mean anything, it doesn't translate well from Japanese, or they mean something and no one on the Internet seems to know what it is.

Since the 13g (3 rotor) and 13j (4 rotor) both existed but both were changed to 20b and 26b. To make it even more meaningless the 13b was built off the 12a specs and not the 13a so it isn't some kind of versioning...

Skimmed through this as well. Not sure if that's the same guy who's writing the book for the RX8 due out next year but it's good reading on the rotary's history prior to the 8... but still doesn't talk about what the B means.

http://books.google.com/books?id=XSv...esult#PPA74,M1

 

SEARCH U NOOB !

 

stands for BEAST

 

I typed in 'B' in the quick search. I'll be done with the 5321 posts it brought back in a few hours...

Seriously I don't see it anywhere and engine conventions, naming conventions, engine version, engine names, etc. all bring back squat. Plenty of info on the RX designation and the 13 along with explanations of the different 13Bs but searching on something as common as 13b is near impossible.

Even Rotary Illustrated leaves it out:

http://www.rotaryengineillustrated.c...gines/13b.html

Only hint I can find is that the 12b was the first single distributor but I can't find out if the 13a was single or double so I don't know if that's the sole reason for the designation. This post by Paul talks a little about it but still doesn't get into what it means:

https://www.rx8club.com/showpost.php...&postcount=126

 

Just FYI, the RX-7 Performance Handbook is a GREAT book. Found it by chance at a book store and quickly picked it up.

 

I could be completely wrong but I believe it was in reference to the size/dimensions of the rotor...

 

the 13 references the size of the motor.

im pretty sure its a letter assigned to it. like 12a, (im going to assume this motor had 1200cc of displacement in 1 rotor). and that the 13g and 13j (both having 1300cc of displacement in 1 rotor) are simply alphabetical markers for each engine. they dont "mean" anything.

what does the LS1 stand for? what does the LS7 stand for? afaik, they are just alphanumeric names for the engine. LS being the series and the number being a particular engine model in that series.

 

The LS1->LS7 sequences are based on capacity or output. The LS1 block is the same as teh LS6 block but they have different numbers to indicate the higher output.

The LS big block replaced the LT.

I can't imagine American engineers are doing things in a more logical fashion then Japanese engineers. Germans, maybe, but not US engineers. Course we are talking about rotorheads so maybe they're more creative and happy to keep traditional naming even if they don't mean anything anymore...

Somebody's got to know tho.

 

The 12/13 is based on the liters of the motor not the rotor. 1.3 liter engine = 13a/b. One rotor is actually .65 liters which is why the 3 rotors are all referenced as 20b and the 4 rotor 26b.

 

I'm sure, and hoping, he knows what the 13 and 12 stand for. It's the letters he's struggling with, which I don't know of either!

 

13balls

 

Good question. If i had to guess i would think the 13B simply stood for an engine coming after the 13A......just a guess i have no freakin clue. If this was the case then why jump straight to the 20B and not have a 20A? Same with the 26B. What do all the B engines have in common that would make them hold on to that particular letter?

 

From what I can gather (this is from wikipedia so take it as you will) the 13B is so named because it's a 1300cc engine, the B designator is given to distinguish it from the 13A.

The 13B is in no way related to the 13A, instead is a "bored out" 12A with the rotors being 80mm deep as opposed to the 70mm of the 12A. The following is speculation on my part since the page doesn't say so, but the B in the 13B is probably inheritied from the 12B, which is itself an improved version of the 12A.

13B stuck. the 13G and 13J designations are for engines that used peripheral port intakes, the 20B and 26B engines are side port intakes just as the 13B is, and in fact both engines are based on the 13B, only just with "plates" added to the end. So... it would make sense to retain the B designator, altho under that rationale the renesis should be classified as a 13C

when the 16x comes out, I would expect it to retain the B designator for historical purposes by now.

 

From what I can gather (this is from wikipedia so take it as you will) the 13B is so named because it's a 1300cc engine, the B designator is given to distinguish it from the 13A.

The 13B is in no way related to the 13A, instead is a "bored out" 12A with the rotors being 80mm deep as opposed to the 70mm of the 12A. The following is speculation on my part since the page doesn't say so, but the B in the 13B is probably inheritied from the 12B, which is itself an improved version of the 12A.

13B stuck. the 13G and 13J designations are for engines that used peripheral port intakes, the 20B and 26B engines are side port intakes just as the 13B is, and in fact both engines are based on the 13B, only just with "plates" added to the end. So... it would make sense to retain the B designator, altho under that rationale the renesis should be classified as a 13C

when the 16x comes out, I would expect it to retain the B designator for historical purposes by now.

 

Kinda right. I think you missed a few points. The 12b came before the 13b which means the b stood for something. The 13a isn't even a data point.

Still it really doesn't make any sense at all if you add in our 13b MSP.

The only thing I can think of is the B is specific to a design spec like a single rotor. Maybe based on the size of the rotor? I know they fudged with 12a in order to produce the 12b but beyond that single distributor is the only thing I can see that might actually have a relation to the B.

Pretty sad no one actually has an answer.

 

The the A and B stand for width? Since the 13B was wider than the 12A... ? Guess.

 

The numbers represent metric displacement.

The letters "A" & "B" represent the combination of two basic production engine configuration parameters, eccentricity (the distance from the center of eccentric shaft rotation to the center of the rotor) and generating radius (the distance from the center of the rotor to its apex).

 

I hope this answers your questions,,,,,


40A

Mazda's first prototype Wankel was the 40A, a single-rotor engine very much like the NSU KKM400. Although never produced in volume, the 40A was a valuable testbed for Mazda engineers, and quickly demonstrated two serious challenges to the feasibility of the design: "chatter marks" in the housing, and heavy oil consumption. The chatter marks, nicknamed "devil's fingernails", were caused by the tip-seal vibrating at its natural frequency. The oil consumption problem was addressed with heat-resistant rubber oil seals at the sides of the rotors. This early engine had a rotor diameter of 90 mm (3.5 in), an offset of 14 mm (0.6 in), and a depth of 59 mm (2.3 in).

L8A

The very first Mazda Cosmo prototype used a 798 cc L8A two-rotor Wankel. The engine and car were both shown at the 1963 Tokyo Motor Show. Hollow cast iron apex seals reduced vibration by changing their resonance frequency and thus eliminated chatter marks. It used dry-sump lubrication. Rotor diameter was up from the 40A to 98 mm (3.9 in), but depth dropped to 56 mm (2.2 in).

One-, three-, and four-rotor derivatives of the L8A were also created for experimentation.

10A

The 10A series was Mazda's first production Wankel, appearing in 1965. It was a two-rotor design, with each displacing 491 cc for a total of 982 cc. These engine featured the mainstream rotor dimensions with a 60 mm (2.4 in) depth.

The rotor housing was made of sand-cast aluminum plated with chrome, while the aluminum sides were sprayed with molten carbon steel for strength. Cast iron was used for the rotors themselves, and their eccentric shafts were of expensive chrome-molybdenum steel. The addition of aluminum/carbon apex seals addressed the chatter mark problem.

0810

The first 10A engine was the 0810, used in the Series I Cosmo from May, 1965 through July, 1968. These cars, and their revolutionary engine, were often called L10A models. Gross output was 110 hp (82 kW) at 7000 rpm and 130 Nm (96 ft·lbf) at 3500 rpm, but both numbers were probably optimistic.

The 10A featured twin side intake ports per rotor, each fed by a one of four carburetor barrels. Only one port per rotor was used under low loads for added fuel economy. A single peripheral exhaust port routed hot gas through the coolest parts of the housing, and engine coolant flowed axially rather than the radial flow used by NSU. A bit of oil was mixed with the intake charge for lubrication.

The 0810 was modified for the racing Cosmos used at Nürburgring. These engines had both side- and peripheral-located intake ports switched with a butterfly valve for low- and high-RPM use (respectively)

Applications:

* 1965–1968 Mazda Cosmo Series I/L10A

0813

The improved 0813 engine appeared in July, 1968 in the Series II/L10B Cosmo. Its construction was very similar to the 0810, but the ports and carburetion were revised to produce 130 hp (96 kW) at 7000 rpm and 140 Nm (103 ft·lbf) at 5000 rpm. Again, these were Japanese net output figures.

Applications:

* 1968–1972 Mazda Cosmo Series II/L10B

0820

The 10A was substantially revised for wide-scale production in the R100/Familia Rotary. Many changes were made in an effort to reduce production costs. These included the use of cast iron in the housing sides, less-expensive molded (instead of sand-cast) aluminum for the housings, and chrome-steel for the eccentric shafts. The port arrangement remained the same, but exhaust was no longer routed around the housing.

Japanese-spec gross output was 100 hp (75 kW) at 7000 rpm and 98 ft·lbf (133 Nm) at 3500 rpm. The use of less-expensive components raised the weight of the engine from 224 lb (102 kg) to 268 lb (122 kg).

Applications:

* 1968–1973 Mazda R100/Familia Rotary

0866

The final member of the 10A family was the 1971 0866. This variant featured a cast-iron thermal reactor to reduce exhaust emissions and re-tuned exhaust ports. The die-cast rotor housing was now coated with a new process: The new Transplant Coating Process (TCP) featured sprayed-on steel which is then coated with chrome. Gross output was 105 hp (78 kW) at 7000 rpm and 135 Nm (99.5 ft·lbf) at 3500 rpm.

Applications:

* 1972–1974 Mazda RX-3 (Japan-spec)

13A

The 13A was designed especially for front wheel drive applications. It had two 655 cc rotors for a total of 1310 cc. This was the only production Mazda Wankel with different rotor dimensions: Diameter was 120 mm (4.7 in) and offset was 17.5 mm (0.7 in), but depth remained the same as the 10A at 60 mm (2.4 in). Another major difference from the previous engines was the integrated water-cooled oil cooler.

The 13A was used only in the 1969–1972 R130 Luce, where it produced 126 hp (94 kW) and 126 ft·lbf (172 Nm). This was the end of the line for this engine design: the next Luce was rear wheel drive and Mazda never again made a front wheel drive rotary vehicle.

Applications:

* 1970–1972 Mazda R130

12A

The 12A was a "bored-out" version of the 10A — the rotor diameter was the same, but the depth was increased by 10 mm (0.4 in) to 70 mm (2.8 in). Each of its two rotors displaced 573 cc for a total of 1146 cc. The 12A series was produced for 15 years, from May 1970 through 1985. In 1974, a 12A became the first engine built outside of western Europe or the U.S to finish the 24 hours of Le Mans.

In 1974, a new process was used to harden the rotor housing. The Sheet-metal Insert Process (SIP) used a sheet of steel much like a conventional piston engine cylinder liner with a chrome plated surface. The side housing coating was also changed to eliminate the troublesome sprayed metal. The new "REST" process created such a strong housing, the old carbon seals could be abandoned in favor of conventional cast iron.

Early 12A engines also feature a thermal reactor, similar to the 0866 10A, and some use an exhaust port insert to reduce exhaust noise. A lean-burn version was introduced in 1979 (in Japan) and 1980 (in America) which substituted a more-conventional catalytic converter for this "afterburner". A major modification of the 12A architecture was the 6PI which featured variable induction ports.

Applications:

* 1970–1972 Mazda R100
* 1970–1974 Mazda RX-2, 130 hp (97 kW) and 115 ft·lbf (156 Nm)
* 1972–1974 Mazda RX-3 (Japan), 110 hp (82 kW) and 100 ft·lbf (135 Nm)
* 1972–1974 Mazda RX-4
* 1972–1980 Mazda Luce
* 1978–1979 Mazda RX-7, 100 hp (75 kW)
* Lean-burn
o 1979–1985 Mazda RX-7 (Japan)
o 1980–1985 Mazda RX-7 (USA)
* 6PI
o 1981–1985 Mazda Luce
o 1981–1985 Mazda Cosmo

Turbo


The ultimate 12A engine was the turbocharged and fuel injected engine used in the Japan-spec HB series Cosmo, Luce, and SA series RX-7. In 1982 a 12A turbo powered Cosmo coupe was officially the fastest production car in Japan. It featured "semi-direct injection" into both rotors at once, a technique that was much more successful than it would appear. A passive knock sensor was used to eliminate detonation, and later models featured a specially-designed "impact turbo" which was tweaked for the unique exhaust signature of the Wankel engine. The engine continued until 1989 in the HB Cosmo series but by that stage it had grown a reputation as a thirsty engine.

Output was 165 hp (123 kW) at 6000 rpm and 186 Nm (137 ft·lbf) at 4000 rpm.

Applications:

* 1982–1989 Mazda Cosmo
* 1982–1985 Mazda Luce
* 1984–1985 Mazda RX-7

12B

The improved 12B was quietly introduced in 1974. In the US it was the start of the single distributor engines.

NOTE: the previous 12A & 10A engines used the twin distributors.

Applications:

* 1974–1978 Mazda RX-2
* 1974–1978 Mazda RX-3

13B


The 13B is the most widely produced engine. It was the basis for all future Mazda Wankel engines, and was produced for almost 30 years. The 13B is no relation to the 13A. Instead, it is a lengthened version of the 12A, having 80 mm (3.1 in) thick rotors. It had the largest displacement yet at 654 cc, for a total of 1308 cc.

In the United States, the 13B was available from 1974 through 1978 and was then retired until the 1984 RX-7 GSL-SE. It disappeared from the US market again in 1995, when the last US-spec RX-7s were sold. The engine was continually used in Japan from 1972's Mazda Luce/RX-4 through 2002's RX-7.

AP

The 13B was designed with both high performance and low emissions in mind. Early vehicles using this engine used the AP name, which signified these two characteristics.

Applications:

* 1975–1980 Mazda Cosmo AP
* 1974–1977 Mazda Rotary Pickup
* 1975–1977 Mazda Roadpacer
* 1973–1978 Mazda RX-4
* 1975–1980 RX-5

13B RE-EGI

A tuned intake manifold was used in a Wankel engine for the first time with the 13B RE-EGI. The so-called Dynamic Effect Intake featured a two-level intake box which derived a supercharger-like effect from the Helmholtz resonance of the opening and closing intake ports. The RE-EGI engine also featured Bosch L-Jetronic fuel injection. Output was much improved at 135 hp (101 kW) and 133 ft·lbf (180 N·m).

Applications:

* 1984–1985 Mazda HB Luce
* 1984–1985 Mazda HB Cosmo
* 1984–1985 Mazda FB RX-7 GSL-SE

13B-DEI

Like the 12A-SIP, the second-generation RX-7 bowed with a variable-intake system. Dubbed DEI, the engine features both the 6PI and DEI systems, as well as four-injector electronic fuel injection. Total output is up to 146 hp (109 kW) at 6500 rpm and 138 ft·lbf (187 N·m) at 3500 rpm.

Applications:

* 1986–1988 Mazda RX-7, 146 hp (108 kW)
* 1989–1991 Mazda RX-7, 160 hp (119 kW)

13B-Turbo

The 13B-DEI was turbocharged in 1987. It features the newer four-injector fuel injection of the 6PI engine, but lacks that engine's eponymous variable intake system. The twin-scroll turbocharger is fed with a two-stage valve to reduce turbo lag. Output is way up at 185 hp (138 kW) at 6500 rpm and 183 ft·lbf (248 N·m) at 3500 rpm.

Applications:

* 1986–1991 Mazda HC Luce Turbo-II, 185 hp (138 kW)
* 1987–1988 Mazda FC RX-7 Turbo-II, 185 hp (138 kW)
* 1989–1991 Mazda FC RX-7 Turbo-II, 200 hp (147 kW)

13B-RE

The 13B-RE was first series production twin sequential turbo systems to be offered for sale.

Applications:

* 1990–1995 Eunos Cosmo, 235 hp (176 kW)

13B-REW

A twin-turbocharged version of the 13B, the 13B-REW, became famous for its high output and low weight. The twin Hitachi HT-12 turbos were operated sequentially, with the primary providing boost until 4,500 rpm, and the secondary coming online afterwards. Output eventually reached, and may have exceeded, Japan's "maximum" of 280 DIN hp (206 kW) for the final revision used in the series 8 Mazda RX-7.

Applications:

* 1992–1995 Mazda RX-7, 255 hp (190 kW)
* 1996–1998 Mazda RX-7, 265 hp (197 kW)
* 1999–2002 Mazda RX-7, 280 hp (206 kW)

20B,,,

In Le Mans racing, the first three-rotor engine used in the 757 was named the 13G.

The main difference between the 13G and 20B is that the 13G uses a factory peripheral intake port(used for racing) and the 20B uses side intake ports.

It was renamed 20B after Mazda's naming convention for the 767 in November of 1987.

The three-rotor 20B-REW was only used in the 1990-1995 Eunos Cosmo. It was the world's first volume production twin-turbo setup featured in both 13B-REW & 20B-REW form. It displaced 1962 cc (three 654 cc rotors) and used 0.7-bar (10.2 psi) of turbo pressure to produce 300 horsepower (224 kW) and 300 foot-pounds force (407 N·m).

13J

The first Mazda racing four-rotor engine was the 13J-M used in the 1988 and 1989 (13J-MM with two steep induction pipe) 767 Le Mans prototypes.[1] This motor was poorly designed, and was replaced by the 26B.

R26B

The most prominent 4-rotor engine from Mazda was used exclusively for various Mazda-built GT cars (including the 767 and 787B) in replacement of the older 13J. In 1991 this engine in a 787B became the first from outside the U.S. or Western Europe and the first (and so far only) car with anything other than a reciprocating engine to win outright the 24 hours of Le Mans race. It displaced 2622 cc and built 700 hp (522 kW) at 9000 rpm. The engine design originates as a single 13B with: an additional rotor and housing added at each end, continually variable geometry intakes, and an additional (third) spark plug per rotor. The R26B's rotor housing can be purchased at retail from Mazdaspeed, but no internal parts are available to the general public.

13B-MSP Renesis

The Renesis engine – also 13B-MSP, for Multi Side Port –, which first appeared in production in the 2003 Mazda RX-8, is an evolution of the previous 13B. It was designed to reduce exhaust emission and improve fuel economy, which were two of the most recurrent drawbacks of rotary engines. Unlike its predecessors from the 13B range, it is naturally aspirated, leading to lower power from its two versions (Mazda RX-7's twin-turbocharged 13B-REW (280hp).

The engine entailed two major changes. First, the exhausts ports are no longer peripheral but are located on the side of the housing, which allowed engineers to eliminate overlap and redesign the intake port area. This produced noticeably more power, thanks to a better compression ratio. Second, the rotors are shaped differently, especially their side seals and low-height apex seals, which offer optimized lubrication.

These and other innovative technologies allow the Renesis to achieve 49% higher output and dramatically reduced fuel consumption and emissions (the RX-8 meets LEV-II). It won International Engine of the Year and Best New Engine awards 2003 and also holds the "2.5 to 3 litre" size award for 2003 and 2004, where it is considered a 2.60 L engine. Finally, it was on the Ward's 10 Best Engines list for 2004 and 2005.

16X,,

Also known as the Renesis(2), made its first (and so far only) appearance in the Mazda Taiki concept car.

The Mazda press release regarding the engine:

Next Generation Renesis (Rotary Engine 16X) In developing the next-generation Renesis, Mazda made a thoroughgoing revision of engine dimensions including the trochoid rotor housing, adopting a longer stroke and larger displacement of 1600cc (800cc x 2) aimed to raise thermal efficiency and boost torque at all engine speeds. By employing the Hydrogen RE design policy of a direct injection system and aluminum side housing, as well as various other measures, we are further promoting the rotary engine’s merits of light weight and compact size.

 

Hey Easy... that's what RK posted in his first post.
He posted the Wiki page link... but thanks for taking up most of the page

 

^I hate clicking links.

 

Ok. That makes some sense. In laymans (ie. my) terms it's going to be based on the size/shape of the eccentric shaft releative to the size/shape of the rotors.

So essentially Mazda hit a nice ratio with the 12b, used that for the 13b, and has only made changes that affect the rotors/housing/etc. in the renny without affecting the ratios used between the shaft and the rotors.

Is the assumption today (or maybe it's known) that the 16x is going to use the same, unmodified concept and is generating more displacement through other gains? Or did Mazda determine a better ratio - which would mean we'd see a 16c.... Probably a post for another day or I'll drop back into some of the old monster 16x threads and see if it's been discussed.

 

Not sure how the "X" is being used....
Could be a "to be decided" or maybe they are trying to be hip with the Generation X.
I guess we'll have to wait and see...

 

Yeah. I think it's being used to indicate it's a prototype but I guess it could be what they're planning on using. Be kinda weird if they did that.

And I forgot to ask - how do you know it has to do with the shaft/rotor apex distance? I assume it's easy enough to confirm if I can find a bunch of spare rotary engines lying around ( ). Also interested to see why the 20B/26B renaming occurred - whether it was because they changed it from the J/G when they put in the 3rotor/4rotor eccentric shaft or if it was something else.

 

I keep random notes while visiting various websites and reading materials.
I'll see if I can find the site I copied that from.

 

OK... here is the link to the page that explains the naming convention:
http://turborx7.com/faqs.htm

Very informative site and good to browse through the various pages on the left side... especially under the 'Basics' section.

Also, at the bottom (left pane) you'll see a 'RX-8 Renesis Info/Specs' area:
http://turborx7.com/rx8renesis.html
I've mentioned in the past that its good for everyone to observe the Renesis Module flash animation to better understand whats going on under the hood.
This is where you can download the animation module.