Grizzly

Does any one know what the 20b engine types are?

Sound daft? i'll explane, With the 13b there are a few diffrent types like the 13bt,13b-re and 13b-rew i have read there is the same in 20b engines (20bt,20b-re and 20b-rew) is this correct or have i been misinformed?

Also if this is correct is the 20b-rew is basicly a 13b-rew FD engine with an extra rotor?

I am geting a little confused as mazda have been making 20b's for a long time and it would make sence for them to follow the Rx's Evolution.

Thanks.....Chris

now

iTrader: (1)

so 7 is all we have so far
now has a 454
and a B991
rx720bt has a 421
mad20b has a A 021
j9fd3s has a 246
RETed has a 669
Bitchn7 has a 757
Attila the Fun has a 392
To start with,
it seems that this info has been kind of kept secret
for what ever reason, I am sure it has nothing to do
with the desire to keep prices up or to dump old series
blocks which there are more of.
regardless now that I have my B991 here it is.
what all the numbers mean.
which is not really good news
It looks like the old engines are the only ones making
it to North America, since I've only seen one other
newer motor.
I do not know the total numbers of "runs" that were
made but it goes like this:
the first run went from 001 to 999
then the next run was A 001 to A 999
there may have been more than 1000 per run but this is
what I have seen.
next came:
B 001 to B 999
then last was:
C 001 to C 999
the differences between the run numbers are strength.
the first 2000 motors were the first run and are the
ones that mazda had the problems with, and had
changed lots out on warranty to the newer motors
at great expense.
I was told that the first run motors have a short life
and its not a matter if they will fail, rather when,
especially under higher boost levels (anything over 12psi)
the strengthened housings of te 2nd run (B toC)
make the motor much more reliable and hold higher boost.
what can you do if you have a first run motor?
#1 dowel pin the old housings
#2 find a 2nd run motor
#3 order new housings from mazda
#4 don't run high boost.

Hope i dont get into to much trouble for this
matt

now

iTrader: (1)

forgot something.
I think the 001 to 999 might have gone over the 999 into 4 digits but am unsure of this, but the fact remains
the same if you do not have a B or a C in front of the
run number you have a first run motor.
I might take pictures of the differences and post them
as well since it is easy for someone to take a punch set
and put B's or C's in front of the first run numbers
matt

j9fd3s

iTrader: (3)

well since the 20b was only put into 1 car, the jc cosmo, there is only 1 style of 20b. the factory refers to the 20b as an rew, the rew means that it has twin turbos, the fd is an rew, and so is the 13b cosmo engine. people refer to the 20b as a bt or re, because it gets confusing sicne 3 different motors are rew.
the cosmo engines are the "missing link" between the 89+ fc motors and the fd engines, they have features of both.
like the fc engines, the cosmo motors have a crank angle sensor, 550cc injectors, stamped fuel rails, an airflow meter. like the fd motors the cosmo's have side feed primaries, the sequential turbo system, the fuel temp sensor (no more flooding...).
it also has some things unique to the cosmo, dual(ing) thermostats, the intake with equal size runners and the larger plenum, and those exhaust sleeves.

mike

Attila the Fun

iTrader: (1)

I wish you had mentioned this in the original post. Being perpetually in a hurry, I just grabbed the last three digits off the rotor housing and hurried off to my next task. There are other characters in from of the "392". I'll go and pay more attention, this time.

RX-Heven

iTrader: (1)

As for swapping the rotor housings, 13b-rew(3rd gen) housing would be a sufficient fix I imagine. BTW Kurgan, you were right about the exhaust sleeves, either replacing the sleeves or the entire housing is the only real option for a big single.

What about the strength of the e-shaft. Are they different also. I talked to MazdaComp, uh, I mean Mazdaspeed about it and they did not know one way or the other, though they have heard about many e-shaft problems with 20b's. They do have e-shafts available ($825) but are original equipment, which could possibly be weak/strong depending on production run.

now

iTrader: (1)

its not the rotor housings where the strength has been
added its the side or intermediate housings.

as for the strength of the e shaft I have only heard of
a couple people having problems in that area, I have
never seen even a picture of a 20b eshaft failure.

I have heard and seen a pic of a 13b eshaft which had
failed just in front of the flywheel, and since the 20b
shaft is no thicker in that area I would imagine that
would be where to expect it to fail as well.

there is a extra bearing in the 20b to support the eshaft
so it's no worse than a 13b for bearing area.
What causes more problems? I would say reving a 13b
to high rpm stresses the eshaft more than high hp at
low rpms.
conclusion, the 20b eshaft is lots strong enough if
the rpm is kept under 6500 to 7000 rpm which seems to
be where the power drops off anyhow.
I believe that the eshaft has been wrongfully
blamed for causing engine failure, when in reality it
was the fault of the weak intermediate housings.
from what i understand if the center rotor fails
is more to do with the weak intermediate housings
than eshaft flex.

Correct me if i am wrong but this is what i believe.
matt
ps. mazda comp / mazda speed sux!
they are to busy to even find me a part number!

Jeff20B

iTrader: (13)

Not to say anything bad about Atkins, but I noticed they tend to grind the numbers off of 20B rotor housings. Here's a pic of an engine they prepared a year or two ago (I think):

Maybe you're right about some people trying to keep the production run numbers secret. Here's the link to the page I got the pic from:
http://www.revolutionrotary.com/truck.html

now

iTrader: (1)

I can see from that picture that is a B series motor to..
No its not just the black paint
matt

now

iTrader: (1)

That's interesting! was looking around that Atkins web
site and seen this, it appears to be a D series motor!

Jeff20B

iTrader: (13)

You found that pic at Atkins' website? Or Revolution Rotary? Anyway, do you think that D series engine came straight from Mazda for like $8000 or whatever the current price for a new 20B is?

now

iTrader: (1)

ok your right it was on Revolution Rotary's page.
as far as i know C was the highest that were being put
into cars, they may have ordered new housings.
matt

Grizzly

What is the Diffrence between the 13b -rew housings and the 20b ones? (apart from it says 13b and 20b on them)

Are 13b and 20b parts interchangable? as 20bs are geting rare?

Thanks.

Jeff20B

iTrader: (13)

13BREW housings have larger exhaust sleeves. The only prob with using them on a 20b is that they'd say 13B and there'd be three of 'em. Ask Kurgan how much fun it was to change sleeves in his 20B housings.

j9fd3s

iTrader: (3)

1. the only rotary engine that you can't buy all the parts new for is the pre 76 stuff, everything else is still available.
2. in the pic of the black painted motor, you can see the 391 stamped into the front steel
3. the "d" series could be the current production engines, they are still available new
4. the it is likely that replacement rotor housings do not have a stamp of any kind, if you buy a new front steel for a 13b it wont have any numbers on it

mike

peejay

Am I the only one who thinks it'd be cool to make a 2-rotor 20B? Just the front two rotors, for a REALLY BEEFY 3-bearing setup. Would weigh a ton, and be longer than a standard 13B, and you'd have to reshape one of the rear rotor's intake ports so the are matches front front rotor's primary, but still.... Neat idea.

Or, if 20B rotor housings are available, how much do they run vs. 13B housings? If only to see 20B on top of the engine when you go to check the oil...

RETed

Doesn't Lance Warren(?) of 3rotor.com have some sorta Registry for this stuff?

I kinda only heard about it, since I've mysteriously have been subscribe to the 3rotor mailing list without doing anything...


-Ted

now

iTrader: (1)

you can see 391 on that housing,,, wow your eyes are
better than mine!!!

matt

now

iTrader: (1)

ok i think i see it there that could be a 691
matt

j9fd3s

iTrader: (3)

haha, well there a number there....

mike

now

iTrader: (1)

ok make fun of me!
I very speak well, thank you please
matt

Jeff20B

iTrader: (13)

It could be 690 if the 0 wasn't hit hard enough to show up well, and at a slight angle.

j9fd3s

iTrader: (3)

haha, i thought you were right! my eyes arent that great either....

mike

RX-Heven

iTrader: (1)

What would be the difference in new side or int. housings as opposed to the original?
Where has this strength been added? Are the new housings definateley 2nd run?
Or do new housings just have less wear and tear than the original?

To sound more stupid than usual, but don't the housings already have dowell pins in them?

now

iTrader: (1)

difference is stronger areas around the dowel pins.
new housings are all the stronger version.
dowel pin mod is to add extra dowels, something
I have no interest in doing.

matt
ps. rx-heven i dont think i seen your motor number posted.