How many versions of the 13B are there and how do they differ? (RE/T/BRE/BREW) Thanks

Don't forget the '74-'75, '76-'78, and '84-'85 US spec 13Bs. There were some JDM-only engines. They have three little aluminum out-croppings around the spark plugs, or a full shroud like FB 12A rotor housings do.

i'm actually working on that, ive got 9 different ones right now, and i have 74-83 all lumped in together



mike

What is the difference between them? (or are you working on it j9fd3s?)

well basically as time goes on the rotors get lighter, the ports get small and then bigger, they add turbos etc. i have a basic spreadsheet right now i can post if you want



mike

please do!

ok the abbrivations are

nm = newton meters its metric torque



i used the mazda # for each engine so thats the far left #

nf01 = 20b

n3a1 = fd

n390 = 13b cosmo

n370 = 89-91 t2

n318 = 86-88 t2

n350 = 89-91 na

n326 = 86-88 na

n304 = 83-85 13b 6 port

1757 = 74-82 carby 4 port



hmm it wont let me upload the spread sheet

mike

post it in your album then link it here

I know a little about the older styles. '74-'75 had different housings which were sort of a go-between from '71-'73 to the later style and say 13B up near the threaded things that stick up for emissions devices/rat's nests. '76 had more modern housings which resemble pretty much any later housings untill the GSL-SE. Then there are the later ones from possibly '78-'82 with carbs that have either three bits of aluminum, or a complete shroud which requires a thin walled socket or NGK BR8EQ-14 plugs. These also have a single tube in the exhaust ports that can be cut away fairly easily when porting. https://www.nopistons.com/forums/pub...IR#>/smile.png ('74-'76 are a little more involved when porting)

ya, i'm still looking for info on some things. like hp ratings between a 74 13b and a 76. the port timing IS different, but i dont know if they have a hp rating difference?



mike

'74-'75 exhaust ports are close in size to '73 12A ports on the outside. '76 and later are larger, thank goodness. It's ok to remove the sleeves in '74-'75, or so I've read. https://www.nopistons.com/forums/pub...IR#>/smile.png

i know you can spot a 74-75 motor by the 1757 number stamped into all the steels. the 76-78 ones are 3870 something, one of the things i need to look up



mike

I've seen 1757 on several front counterweights.

that would balance any 74-85 13b rotor. my r100 came with a 73 rx3 motor, thats the twin dizzy bottom mount starter motor, super wierd



mike

I've seen a pic of one of those. The rear plate is missing the upper inspection hole. Quite weird.

yeah its really wierd



mike

Kinda reminds me of a 20B. So does the waterpump pulley's distance from the main pulley.

wait til you see the 20b main pulley, its giagantic!



mike

Oh my, it is! The waterpump pulley also has a larger center hole. It tried fitting my FC waterpump pulley and it didn't go past the center thing.



I was wrong about the distance from the main pulley to the waterpump pulley. It's actually lower and pretty close on a 20B. I'll have to check out pics of some '73 12As when I get a chance.



I briefly installed my FC main pulley on the 20B and noticed the timing marks are offset by maybe 20-30 degrees. Interesting. I'll just line up each mark on the 20B pulley before I take it off and put the FC pulley on it to mark it. Then I'll have a baseline to measure 120º both directions and mark them. How did you accurately mark your larger 20B pulley for 120º and 240º?

i dont remember exactly, i think i marked every 90degrees, and then for 120 and 240 i did half of 90? i ended up making a big spray paint mark, thats different for 2 and 3, so its easy to see and tell apart. oh yeah the firing order is 1-2-3, the same code and idiot would have on thier luggage....



mike

Ah, Spaceballs. https://www.nopistons.com/forums/pub...IR#>/smile.png



I think FC and FB pullies are exactly the same size. Well, I'll know soon enough.



Ok, I've got them both sitting here and the size difference is very small. I bet it'll be so close that it won't really affect anything.



Oh man, it's like 361mm with my cloth tape measure wrapped around it. It's also a hair larger than the FB pulley when held end to end. I guess that's where the extra mm comes from. I'm not too worried. I'll just measure from both directions and average the marks before I cut them with a small triangle file. The only part that worries me is getting it lined accurately up on the 20B hub.



The FC has a 15º L/T split. This FB pulley has a 20º split. I think the 20B also has a 15º split. Somebody once said it did. I could find out from my pulley, but I don't want to bother with the mathmatics.

the cosmo is the missing link between the s5 t2 and the fd. so i'd bet its an fc 15degress split. i should make clear too, that my 120 and 240 marks arent all that accurate, they are just close, i needed to make sure it had the right firing order



mike

Ah, and the 20B has S5 rotors in it. I guess the rest depends on the plug locations in the rotor housings. I've got a T2 housing sitting within my 20B mock-up made from three FC and one '76 Cosmo housings and FB side plates.



While hand cranking my 20B, I can see that the apex seals pass by in order of 1-2-3. Perhaps the 13G had a different order, but I'm pretty sure all 20Bs had 1-2-3.



My pulley has to be as accurate as possible because the three pickups in the dizzy have to be aligned with the marks on the pulley. Talk about setting your timing the hard way! Oh well, the trade-off is to have dual Leading sparks per rotor face like FC and later 13Bs. I can't wait to hear it run in this configuration. https://www.nopistons.com/forums/pub...IR#>/smile.png

yeah you have me curious too. divide it like this

That pic takes me back to late '01 when I was first getting a real idea of all the geometry of the 20B's firing order for two Leading sparks. I used my old drafting "mad skillz yo" and came up with a couple different drawings. Then last summer I got back into it and drew some patterns on some cereal box paperboard and traced around them onto some sheet metal.



This was the beginning of my 20B dizzy prototype, complete with Trailing pickups mounted above the Leading ones.



I doubt I'll even hook up Trailing, to tell you the truth. It just doesn't add enough power to the engine. The second Leading sparks sort of do the job anyway. My REPU's engine's idle and low to mid RPM was unchanged. Only high RPM under high load lost like 1HP with Trailing switched off. I'm guessing it was only 1HP because it was barely detectable by myself and a friend, and my electric fan was replaced by a clutch fan and it sucked a lot more power. A lot more! People say those clutch fans use like 5HP. If so, and I could feel it that much, it's probably going out, or my REPU's engine has a lot less than 100HP, or the engine's RPM is low enough to only be producing maybe 50RWHP where it feels sluggish with the fan. The lower the total engine HP, the more a loss of 5HP can be felt. Well, at low RPM, trailing did absolutely nothing for my engine. Pretty weird huh? I could put two of the three pickups back into a stripped dizzy I guess.



I'll see about some audio clips of the 20B once it's running. You can then tell me if it sounds different than everyone else's. https://www.nopistons.com/forums/pub...IR#>/smile.png

i notice mine sounds very different depending on how much timing i'm running. more timing = boomier, my 12a is really loud



mike

That's interesting how it would change like that. I'll be running 20-24º of total advance. My 20B prototype was built on a 12A dizzy.



I'm brainbashing some possible 20B project cars in the Ask Mike section of one of the other forums you visit regularly. Let me know what you think about some of my crazy ideas (MG vs GLC). https://www.nopistons.com/forums/pub...IR#>/smile.png

i dont have a timing split so the trailing limits how far i can advance the 20b, i'm running like 18degrees advance@0 psi, at 10psi its like 6degrees



mike

Still running the E6K?

yup, i have plans for an e11, i dunno about the time frame on that though



mike

Will you have the E11 control your MOP or as we say on the forum, OMP? Timing split that changes with load and/or RPM differences? That's a cool feature.



Well, my 20B has soaked for the full 48 hours. Now I've got to tilt the engine to the side to let the rest of the MMO drain out. Or maybe I'll leave it in for a nice smoke show when it fires up? Heheh!

yep, i'm going to have the e11 run the omp, and it does do timing split rpm vs load. its gonna be fun to play with the split, although right now i'm liking the 10degree split you can get with a dizzy. its funny my timing curve right now is totally doable with a dizzy.



oh i and i vote for smoke show



mike

It's good the E11 can do split RPM vs load. That's the ECU I'd like to get for an FC 20B install. It's funny, I'm into computers and cars, but not at the same time because I'd rather do a carb and dizzy on a 20B. I like to get into technical stuff, so I'm sure I'll eventually do fuel injection, but just not right now, and not on this engine. Maybe on a newer B or C series engine?



I've decided 100% to install the 20B in my GLC (not "nearly 100%" in my REPU, like I mentioned on a different forum). Mostly thanks to Steve84GS because he has a V6 powered GLC, and he's going to do a bridgeported 13B in it soon. I was going to do a half BP in mine, but then the 20B came along. The half BP is going in my REPU so it'll finally have high RPM power and won't require any cutting of the truck. The low RPM will be taken care of by the 4.6 diff gearing and streetported primaries. That's another project that I can't wait to undertake. https://www.nopistons.com/forums/pub...#>/biggrin.png

i kinda of agree, i like my gsl-se its got a dizzy and really simple efi, and it works great, and its got nice accurate timing.



hmm, 20b glc? thats kinda cool you'll be about the only one, and we can still make fun of it, gods little curse? fix a glc go to jail....



i likey



mike

I've never thought of making fun of the letters 'GLC' before. Only Ford and Fiat and a few others. Flaky old rusty dump. Found in a toilet. Hehe.

i worked with some old school mazda guys....



mike

You've got a PM on the other forum about the you know what.

mums the word



mike

Does anyone know where i can find all the technical specifications for all the series of 13b? Im working on a spreadsheet that would cover all this info and am trying to locate some of it. Right now ive got the specs on the 6-port (i think series 4or 5)

Im not looking for someone to tell me all the info, unless of coarse you want too https://www.nopistons.com/forums/pub...1047683827.gif but if someone could point me in the right direction i would appreciate it. Also, once i get the spreadsheet finished, is there a way to post in on the forum so anyone can download it? thanks, brad

i'm kinda working on the same thing, http://members.rogers.com/sofronov/Cars/Ma...zda/Rotary.html

kinda weak on the 13b's, dont forget the shop manual too



mike