Just doing some research and found out that there are several versions? it appears of the 20b. Something to the tune of a set of series like A~G, and some where better than others. Right now theres a couple on EBAY, and i was interested in the short block one from Japan. the seller lists it as a "B" series is this good, or bad? anybody bought there engine directly without going through a importer?

sorry for all the questions. I got about 20G's saved, and I am thinking that with that, and maybe a small loan I culd get the prats I need to swap it out in my car.

Doug

 

DMRH would be better to answer questions like that, but I'll try. There were five or so batches of a thousand units each. The first batch had no letter prefix. For example, my 20B is number 756. Then it progesses as A, B, C and D. There are rumors of an E series, but I don't think even DMRH has ever seen any.

 

So are all the 20Bs w/ letter prefixes what they refer to as "late model series" or only say a C & D model?

 

C and D were crate engines I think.

The non letter series appearantly had an E-shaft that was more prone to flexing or failing than the A or B and later series. Some pre letter engines were rebuilt with a later E-shaft. I think also the 80mm thick plate as well as the rear plate were strangthened in the later production runs.

 

https://www.rx7club.com/showpost.php...&postcount=111

 

What he says..................

.

 

So whats a 90 model cosmo doing with serial # D003 in it? a used engine swap? or maybe a dealer swap? the Car has the 90 model year computer system (93 and newer are subtley different)

I have been trying to figure the whole series thing for a while, and after 4 bodies, and 6 different engines, this is the highest series motor I have gotten, but its in a 90 body so WTF?

Have you come across any like this DMRH?

 

Doug,

I have the "B" series listed on EBAY, do you research here on the forum prior to commiting. check with RETED for motor mounts if you have a FC, and check with Pettit, or pinapple arceing if you have an FD.

Check with the moderators or admin types, one of them has a 3 rotror FD, and has worked his kinks out, he should be a great source of info..... he seems to be a decent chap with some good scoop and probably would welcome some companions in the 3 rotror FD scene.

Kenn

 

No big deal, seen this plenty of times. The VIN of the Cosmo is important to find out its year. A general rule of thumb is........ <<< JCESE-102000 should be a 90 model.

As for the "D-series" engine inside it.......... Replacement change over prior to the end of production in 95. If my sources are correct. The "D-series" where done in 1992 (even though they where fitted to the 94+ models) so this 90-model Cosmo you talk about may have gotten its engine swap in 92 or 93 for example.

Just like the ill-famed NSU-Ro80 a vast majority of the 20B engines where replaced with nothing wrong with them except for flooding or carboned plugs, even popped off hoses. The problem was with Mazda not allowing the dealers to rectify the 20B issues themselves. The engines had to be removed & sent to the factory, a new replacement engine was sent back. Some bright spark thought this would ensure the prestige of the car when in fact it cost Mazda a fortune, shot themselves in the foot & gave the company a major bad taste attitude to the 3-rotor engine that still rings through the company to this day. ( I want to shake his hand......NOT)

I'm only guessing here but I suspect about 30%-40% would have actually been dead with the remaining amount dogged with the above problems.

REgards

 

Good eve. Everyone,
Regardless of the letter series, or prod. serial #'s there are basicly 4 ifferent offerings of the 3 rotor engines. Two are race versions, & two Production versions.
The production 20b's have one significant difference between them which is visually seen.
The area arround the upper dowel pin where the oil galley flows though, is substantially larger, (strenthened) just like in the 3rd. gen Rx7 REW engines in the later built cars & engines.
Internally, they are identical, and dependidng on the intended use, the later offers no real advantage except when turbocharged and poorly tuned.
As for the race engines, the (G) series was a Non-production, race only version which shared some parts w/ the 4 rotor race engines and are narrow at the bottom.
These were the engines built for endurance, Le Mans, & early years IMSA GTO. racing.
The other is the 20b Peripheral port Race " OVER THE COUNTER, COSTUMER " engine which Mazda sold to independent race team either as complete engines, or as build-up competition kits.
This engine consisted of the production 20b with P.P. Rotor Housings, and a Dry Sump lubrication syst. along w/ the dedicated EFI. & race clutch and exhaust.
The (G) series, & (B) series race engines, shared virtually NO components with each other.
The E shaft on the (G) engine is thicker, the Rotor Housisngs are different, The Rotors are of a different casting, lighter, w/ 3mm apex's, and thicher side seals, the side steel plates are different, and the Dry Sump front cover is different, also the water pump in the (G) is propriatery while the (B) engine shares its pump with the 13b family of comp. W/P's. Most other periferals are particulat to the (G). while the 20b share most conponents w/ the 13b family of race parts.
I've been racing Mazda Rotaries since the mid. 80's and arround 3 Rotors, almost as long, both as a proffesional mechanic and a driver in IMSA & SCCA.
I currenly run a 3 Rotor Rx7 in SCCA GT-1, and was last years (2003) Florida Region's class Champion, a class that competavely runs only V-8's. in 04' did NOT compete due to other priorities.
My advise to any one wanting to do a 3 Rotor car, is to buy the one engine demograficly closest to you, and get started ASAP. If You sit arround waiting for the "perfect" engine, at the "perfect" price, to become available arround the corner from Your house, chances are that life will pass you by DREAMING of what You could have done or are planning to do.
Best Regards,

GT1-20b

 

Damn GT1-20b, you sound very knowledgeable. Thx for the info. May I ask how you had your 20b set-up? To have a 20b Fd compete in SCCA GT-1 and win gives us more confidence that installing a 20b really doesn't affect the cars overall handling potential like some would have us believe.

 

The extra "meat" around that area you are talking about is seen on the "C-series" & later engines

As 99% of us dont have access to the 13G or 20B-race engines its the 20B-production ones everyone has a thirst for knowledge of.

Have you ever seen the problem shafts from the 000-999 series yet.???

Great to hear you are racing 3-rotor RX-7's. Consider me green with envy & wishing I was there to help you out.

REgards

 

Happy New Year's to everyone,
My race car is NOT an Fd, it's a full tube frame chassy with modified Rx7/ Mx-6 body work, although You can put any body you want on it. Plan to run Rx 8 bodywork next year.
The chassy is quiet old, originally built as an overweight GT-3 car that never whent anywere in that trim.
Whem I accuiered the car, I installed a P.P. 13b from a Camel Light GTP car I crewed on and eventually drove, then ran it as a Super Production car, and whent on to win the SCCA , SPO Championship the following year, then I stepped up in 2000' and installed the 20b.
and whent racing with the big dogs. 1 year of development, 1 season pleagued with and solving overheating problems, the next season blew the competition away.
I will post some pics of the car & engine later.
As for the Fd, if You follow the Monkey see, Monkey do... going on with the 3rd. gens and 3 rotors, then yes, there are some issues associated with handeling when the rac is moved forward & placed in front of the engine. This thowghs away ALL the ENGENEERING designed in by the Japs. and also destroys the geometry & Ackerman steering qualities built in, so You end up with a car that UNDER STEERS badly and feels heavy in the front.
There ARE other ways to do the "install" that leaves the streering rac exactly were it's designed to be, and the overall balance of the car is not affected AT ALL.
It does require some ingenuity and fabrication, but it's really a no brainer.
I'm currentlly doing one right now, and even useing the strut bar brace over the top of the engine. Bet You've never seen that done an ANY 20b intallation in an Fd ?
I 'll must leave now, and get ready for the festivities.
Whish every one a very Happy New Years Celebrations, and will continue NEXT YEAR !

GT1-20b.

 

Firts I'd like to say I've been a long time fan of You're web site, You 've dedicated a lot of research and time into it, and glad to corresponnd with You.
As to the E-shaft question, I was never aware of a problematic unit.
Ive built many engines, both for all out racing, and street engines, and have never encountered a problem with the crank.
I was fortuned to have been garaged right next to the Japaneese tean in 1987 for the 24 hrs of Daytona for a whole week, and we shared stories the whole time. They did'nt know their way arround well, So we helped them out & made friends, they were running the 4 rotor in the US. for the firs time, they showed me the E-shaft, and explained the differene of the coupling on previous engines and their draw backs. We were running a GTP-Light with a 13b PP.
To my knowledge, as of the firts production engines, the conical type slip coupling had been adopted. The 20b production run was a development of the race program using "off the shelve" production parts, and the "Race 20b costumer engine" was done the same, in an effort to make engines affortable and attractive to indepandent racers.
I would venture to say that any problems that people may have had, may be related to LUBRICATION issues not nessesarally the shaft it self.
Many Drag Racers attempt to run these engines making 3 to 4 times their rated power, on a stock lubrication system designed for 300 Hp.
The Oil pump from a 3 Rotor, is essentially the same as the 13b REW. but the 3rd. Rotor, allows for 33 % more oil press. scape paths, and therefore the pump can't keep up.
All REAL race engines, from REAL race teams, making REAL Reliable Hp., All use Dry Sump lubrication systems.
The cost of the Dry Sump, against othe cost of the engine in Hi- HorsePower trim, is cheap insurance, but most people don't see it that way.
Best Regards to You & you'rs,

GT1-20b

 

I think it would be unlikely for you to have encountered this problem.

 

Being an importer & enthusiast, I dont actually re-build engines. However, when I was looking into the Cosmo from Japanese contacts, they all warned me of the early ones & their suspect engines.

I took the chance buying an early one once (JCESE-100515) & it arrived with a dead engine. (#635) I refused to pay the balance & the seller sent me another engine freshly rebuilt in Japan. It was installed & I personally ran the engine in for 1000km before giving it to the buyer.

By 1500km it was dead. He was passing a bus from 50kph when he pulled out along side & punched it. The "snap torque" kicked in around 2000rpm (full boost at 1800rpm) & the centre rotor lost compression after going for a "wobble". I fitted a B-series "import" engine under warranty & never heard from the car again.

The dud that arrived with the car was rebuilt & installed in a series-5 RX-7 circuit car. It popped 3 times on the dyno before the rotary shop we on-sold it to worked out the shaft was faulty. Replaced the shaft on re-build #4 & the engine was fine.

The "re-built" engine (#700 approx, failing memory here) that popped at 1500km, was rebuilt with a new shaft included. The run-out on the shaft was way out after its little problem & as it remains unusable, it still sits on a display shelf at a rotary shop destined for customers viewing pleasure forever.

Rotary guys from Japan said the first batch shafts had a design fault where the front rotor slides on. It was fixed for the A-series engine onwards. Which explains why this problem only occurs on the 000-999 engines.

GTI-20B. Would have loved to be a part of your rotor racing ventures, whether 2-3 or 4 rotor ventures. Best I can boast is part of the 2002 Bathurst-24hr team with a production spec series-8 RX-7 (99-02). I was the technical/electronics/electrical guy. Am also part of a 20B sport compact drag race team as the techo guy aswell but I do prefer more than 7 seconds of action. (Our RX-7s best time is 6.95)

For your viewing pleasure. Here is what a friend of mine had delivered the other day. PP rotor housings came with it aswell as the centre plates etc. Quality is very poor as I took the pic with the mobile phone camera. Those Nokia 7250 cameras are pretty average. At thi stage, it remains a secret as to its destined path. When I am allowed, I will pass it on.

 

 

can some body please help me decide if i should change my 93 rx7 motor to a 20b motor is it worth it and would be streetable and would i loose value in the long run of my car. please help me.

 

NEWBIE, READ! lol https://www.rx7club.com/20b-forum-95/20b-faq-links-370451/

A 20B motor will run you about $5K to get (if you find one), and costs about $15K to install if you do everything YOURSELF, or $35K if done by a shop. That's thirty-five THOUSAND dollars. Aka, you can buy TWO FDs for that price

The best help I can give you is to be VERY familiar w/ the 3rd Gen sticky FAQ. Read it all. Closely. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

 

fd newbie i have a 20b motor already and the subframe i have a friend that wants to buy it but i need it some help deciting on what to do. I like my car the way it is and dont want it to loose value since the 20b is not the original engine.

 

If you're talking about resale value, FDs have crappy reslave value in general. Sure, you can prob get high 20s, maybe even 30K for a 20B FD, but you're gonna put a lot more into the car to get that, so it's a net loss. A 13B is only like $2K, and IMO, if you're worried about resale, it's all bout minimizing how much you put in, and maximizing how much you'll get out of it. Aka, stay w/ a 13B. There's a reason why a FD w/ a 20B swap is considered a STEAL (cuz someone already took a major $$ hit and did the work for you)

Oh and in general, bone stock FDs usually bring in the highest $$, esp. R models w/ low mileage.

 

fd newbie thanks for your help.

 

Np

 

Evil,
About the illustration with the two 3 E-shafts pictured together, the top one is what I 've used and Know well.
The lower one, correct me if I'm wrong, looks to me like a regular 13b piece.
If it is one of those "Early" problematic shafts, how does the main journal for the #1 Rotor attaches on. and where is the part for the shaft that supports the thrust bearings, front counter weight, oil pump drive, crank sensor drive gear, and front pulley arbour ??
Please explain.
Thanks You,

GT1-20b

 

DMRH,
Thanks for the pic. of that 4 Rotor shaft.
It looks like an authentic Mazda piece. You guys must have great connections down there!
I suppose you're getting the 2 fat side plates also?
WOW, what I could could do with that !!!.
If these are available to you, can You please write me a PN with imformation on availability and pricing.
There could be a great market for these peices here.
Only 2 people I know here in the states could have access to these parts, 1) Jim Downing, and 2) Roger Mandaville. Roger is retiered, and Jim will not get involved, plus he is busy with manufacturing the HANS devise for race drivers, & kind off doing racing part time.
I will put up some pics. of my race engine and cars up once I learn how to host them in the forum.
Enviouslly awaiting your reply. Thanks,

GT1-20b