Hi Everyone, I have a nutty questions since i have not been able to get an answer in web. What is the factory 20B Turbo engine stated horsepower and what the hell is Sequential turbo charging I couldn't help to notice when i was taking my engine apart Thanks everyone

 

Why do you keep posting in the TurboXS vendor forum? Your interests don't seem to be with that companies product.

Sequential turbo charging was used on the Mazda RX7 FD. It used a small initial turbo and later a larger turbo would kick in at higher RPM's. It was a way to give the car more low end torque and reduce turbo lag. It was also a nightmare to maintain due to all the vacuum lines that were used to control it. Now, 20 yrs later, advancements in turbo charging cars has progressed to the point where multiple turbos are unnecessary. A single turbo can do the job quite nicely as long as it is sized correctly.
As for the horsepower rating of a 20B, I can't help you. I'm sure others will chime in. I believe the car with a turbo 20B in ALMS racing a few years ago was around 400+ hp. But that was professionally prepared engine. It also ran with a restrictor on the air intake to limit it's hp.

 

The 20B sequential turbo (three rotor) rotary engine used a sequential turbo setup like the later FD RX7. The rated hp was 285hp at 6500 rpm and 295 ft lbs of torque at 3000 rpm. It was used in the Eunos Cosmo 2-door coupe, sold only in Japan and Australia, starting in 1990. The engine was originally called the 13G, but Mazda renamed it 20B for public sales. It was the fastest production coupe in Japan at the time.

 

^only 285 hp, really? The FD had 280 hp during its later years in japan. Seems low, but I dont know.

 

The US spec FD was 245 hp.

 

Wrong.

13G = 3 rotor w/ Peripheral intake
20B = 3 rotor w/ Side intake

Once the engine was changed to a side intake, thats when they changed the name to the conventional scheme

 

I read somewhere that a boost controller could get it up to 350 hp. I don't know if reliability is affected though.

 

280 was the claimed hp but that was conservative. During that period most of the Japanese manufacturers capped their max claim at that figure. Even the last FD may make more that.

We ran a stock 20B (Which is not the same as a 13G) on our dyno with a long runner intake we made here and it made 280 hp without it's turbos.

13G is a competition only 3 rotor peripheral port race engine. They made similar power to the engines being run today in GRAND AM GT (450 hp plus or minus).

Paul.

 

OP: are you sure you want to fly with an engine you barely know? Instead of asking several random questions i'd pick up some literature plus sae papers and start from there.
After some time spent reading all your questions will probably be answered and the eventual "problems" during the build should become minor hiccups

 

Another thing to keep in mind that Japan had regulations in which the rated power of a car was a major influencing factor. I'm thinking it was tax based, but not entirely sure about that.

It's why they continued to offer a 1.6L in the Miata even into the 2000s with the NB series, because the power output was low enough to qualify for the lower bracket or whatever the regulation was. (not finding references to it at the moment)

This may have influenced the stated power rating.

 

I had an "93 FD among my seven rotary cars since 1973, and it was rated 265 hp. The US model ended with the '95 year. But the car was continued in Japan til 2000 and its engine output was gradually improved. The last FDs in Japan were rated at 280 hp. But these were always conservative power numbers to stay within Japanese regulations.

Yes the 1990 20B with sequential turbos had 285 hp. Remember this was designed for a mid-sized four-seater coupe the Eunos Cosmos. Mazda was not building this engine to fit in a sports car. This HP ,at that time, was the most in any production midsized Japanese coupe. The car had a version of quasi four-wheel steering. With the 285 hp coming in at 6500 rpm and the 295 ft lbs of torque coming in at just 3000 rpm, this car could get up and go and was designed to be a high-speed luxury cruiser. Imagine what that engine could have been like in a lighter weight car such as an RX8. The FD engine's sequential turbos were designed similar to those in this 20B engine. It worked well but was a somewhat complicated system. That is why most existing FDs have changed to a single turbo system.Turbo technology has improved to the point that sequential turbos offer no advantage. And yes engine development did change the position of the porting as the years went on.

Certainly many have obtained far greater HP numbers out of 20B engines since then (with and without turbocharging) , with a host of improvements , lighter weight components, and higher compression ratios and higher rpms.

My facts and figures come directly from published Mazda data folks, so they are accurate. Published Mazda data says they called it the 13G as configured in the Eunos Cosmos, but changed the engine name to 20B when they decided on outside sales of the individual engines. Porting may have changed by the time they decided to call it 20B.

 

I would love to see you go one thread without mentioning your seven damn rotary cars since 1973 .... we get it ... now relax

Your facts are coming from the wrong place then, because the Eunos Cosmo used a 20B-REW first off. Second, a 13G was a RACE SPEC ENGINE, porting was different (periph vs side) as well as seals. You are also talking dry sump on the 13G, which wasn't on the 20B unless you looked at the race engines. The 20b was released 5 years after the 13G. They didn't simply take the 13G, scribble off the 13G and stamp down a 20B as its name and call it a day.

 

The acknowlegdment in the History of the Rotary Engine book I am reading, says Kenichi Yamamoto of the Mazda Motor Corporation. I guess he doesn't know what he is talking about. He is just the chief architect of Mazda's rotary engine. But you know more about it than him. I am so glad you are here to enlighten us with your knowledge. We would hate for Kenichi to lead us astray. What you don't understand is that the 13G engines that made it in to racing here may have all been the race peripheral port variety. That doesn't discount that Mazda may have (as Kenichi states) first designated their 1990 engine in the Eunos Cosmos as a 13G in Japan, but changed that to 20B and then gave the race engine the 13G designation. If your read the complete history of the rotary engine from Mazda you would be surprised (as I was) to see how many multiple times ,over the years, that Mazda changed the designation of its different sized and different designed rotary engines.

There was no ONE absolute letter and number designation for each series, and the letters and numbers varied for the Japan home version and the US version and race versions of the same engine, more than once. Do your homework thoroughly.

 

gwilliams, at some point it would be nice if you could provide a link or perhaps scan the page with Yamamoto-San referring to the Cosmo engine as a 13G.

I know a thing or two about rotary engine designations, from code names to names used in production. From 1967 to present. I have touched many that will never be seen by most including the 13A.

If I am wrong I will humbly acknowledge as that is my style.

Paul.

 

Wow, this is all very depressing to read knowing the Renesis can't make these numbers.

 

its depressing to read that a 20b without turbos made about 280 at the flywheel knowing that non turbo Renesis'( RenesisI?) stock blocks can make 260ish at the flywheel?. Its depressing to know that with one less rotor of the same displacement the difference is 20hp NA?

 

This is not correct. The sequential setup in the FD used two identically sized turbos. The sequential setup in the JC cosmo used a staggered sequential turbo setup.

 

Consider the 20B also has 9.0 compression rotors. The HP improvement is not really the point of this motor anyway, its the TORQUE.

A better comparison to your statement would be to find how much a FD motor makes sans turbo and compare that to the 20b.

 

http://www.amazon.com/Street-Rotary-...ref=pd_sim_b_1

http://www.amazon.com/Wankel-Rotary-...ref=pd_sim_b_2


Two good books with rotary history that talk about the various engines, outputs, uses, designations , etc. Both books refer to Mazda Motor Corporation and Yamamoto and other Mazda principles and experts as their sources. You will find word for word the exact specs , engine designations and some subsequent engine re-designations and vehicle facts I quoted, here in these books.

 

Yes. Someone said that the 20b had 295 ft/lbs of torque at 3,000 rpm's. 3,000! Im not worried about the stock numbers though, we all know what the 20b can do and what the Renesis tops out at and seeing as how I have a 2005 model and we're talking about a motor from Japan in 1990 I think its a little depressing. I'll be ok though, lol.

 

Well, someone didn't read up on the engineering tech info of the 13B-MSP concerning the requirements of meeting emission regulations.

 

Horbm, when I said the 20b Eunos Cosmo twin turbo engine used a similar twin turbo system as the later FD, let me clarify it better. The Cosmos and the FD RX7 sequential twin-turbo systems work on the same principle, but they employ different types of turbochargers and different intake and exhaust manifolds.

"The Cosmos uses two Hitachi HT 10 turbochargers, with different primary and secondary turbine designs. The primary turbine is what Mazda calls an "impact" turbine, with a straight blade design. In this turbocharger, exhaust gas first strikes the straight part of each blade almost at a right angle. Gas then flows through the curved part of the blade, increasing speed by reactionary force. The secondary turbocharger has "high flow" curved blades that have less resistance to the incoming gas to aid faster spinning at high rpm.

The FD Rx7's primary and secondary turbochargers employ the same design and geometry, and have high-flow, prominently curved blades. The early 13B-REW prototype engines that powered the first engineering mule and S1 prototypes adopted two Hitachi HT 10-size turbochargers. However starting with the S2 second prototypes, the turbochargers were changed to HT-12s whose flow volume is 20 percent greater than the HT-10's. At the same time the number of turbine and compressor blades was reduced by one each: from 10 to 9 for the turbine and from 11 to 10 for the compressor. "

(from: RX-7-Mazdas Legendary Sports Car by Jack Yamaguchi and John Dinkel)

http://www.amazon.com/RX-7-Mazdas-Le...825764&sr=1-10 A great, big beautiful book with loads of info.

http://www.amazon.com/RX-8-Worlds-Co...1825831&sr=1-1 Yamaguchi's similar book featuring the RX8

Both books have a lot on the rotary engine history and development through the years and models.

 

Understood, but you are missing what I am saying. My point is:
20B twins, ht-10 and ht-15
FD twins ht-12 and ht-12

The fd twins are identical, but the cosmo twins are not identical. Honestly, I respect those sources you linked, but if this is whats written, its not correct. There have been plenty of junked 20b stock twins to verify this.

I do wonder if perhaps the 13B-RE version of the JC cosmo used dual ht-10's. I mean do you really think the 2 rotor and the 3 rotor version of that car have the same turbo setup?

 

http://www.turborx7.com/20bbasics.htm

http://cp_www.tripod.com/rotary/pg20.htm

Two additional different sources about the 20B engine.

 

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

13B-REW

The 13B-REW was first series production twin sequential turbo systems to be offered for sale. Often mis-represented as a 13B-RE due to this symbol being cast into its upper manifold. The 13B-REW from the JC Cosmo series was endowed with the largest side ports of any later model rotary engine.

Compared to the twin turbos fitted to the 13B-REW on the FD RX-7, these sequential turbos received a large (HT-15) primary with a smaller (HT-10) secondary turbo. Injector sizes = 550cc PRI + SEC.

Approximately 5000 13B-REW optioned JC Cosmos were sold making this engine almost as hard to source as its rarer 20B-REW big-brother.[citation needed].

Applications:

* 1990–1995 Eunos Cosmo, 235 hp (176 kW; 238 PS)


A twin-turbocharged version of the 13B, the 13B-REW, became famous for its high output and low weight[citation needed]. 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 unofficial 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)

[edit] 20B
Eunos Cosmo engine at the Mazda Museum
Rotary Engine 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 (Three Rotor Engine) uses side intake ports.

It was renamed 20B after Mazda's naming convention for the 767 in November 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 (70 kPa) of turbo pressure to produce 300 horsepower (224 kW) and 407 newton metres (300 ft·lbf).
[edit] 13J

The first Mazda racing four-rotor engine was the 13J-M used in the 1988 and 1989 (13J-MM with two step induction pipe) 767 Le Mans Group C racers.[2] This motor was poorly designed, and was replaced by the 26B.
[edit] R26B


If you note, there is some slight differing info about these engines, depending on which site you research. And note how Mazda was back and forth on their naming of these engines. I have never personally inspected the turbos on a stock 20B twin turbo engine, but have seen the engine installed on a modified RX7 and it was a sweet, but expensive setup.

Another note: The 20B twin turbo Eunos Cosmos was a four-speed automatic only, no manual transmission.