xenophobe

did a carborated 13b ever come stock in a 1st gen rx7?
i did try a search but all i came across was swap info. it didnt answer the question.

82transam

iTrader: (18)

no, only the GSL SE had a 13b and they were all fuel injected.

KehoeAutomotive

If you see it in something beside for a GSL-SE it was upgraded to the larger motor!

mazdaverx713b

iTrader: (91)

the REPU had a stock 4 port carbed 13B

xenophobe

was there even a carbed 13 then?

other then the REPU... btw what is that?

high-RPM

i was under the impression that some of the other rx models had 13b carbs in them

i also thought some of the upper spec jap rx7s had 13b engines in them

i dont know where i saw this

i could very well be wrong

RacerX7fb

The RX-4 Luce, REPU, and RX-5 Cosmo were all carburated with 4-port 13B's.

wwilliam54

IIRC america was the only one with 13b FB's
japan got 12at's

82transam

iTrader: (18)

your correct, no JDM SA had a 13b, the best was a 12AT

REPU means Rotary Engine Pick up

xenophobe

thanks for the long hand

would there be a diffrence in the truck engine and an rx7 engine? (i.e. stronger housings, higher compression)

wwilliam54

just 4-port carb

cosmicbang

The sizes of the intake ports are different, and for different years.

xenophobe

ports... thats another thing i dont know much about.. i know there are 4 and 6 port engines and that the port size determines how long it is open and how much air/fuel gets in. but i dont understand the benifits of the diffrent number of ports.

sorry im pretty new to this whole rotary engine thing.

ASE_Joe

yea, so what gives?

wwilliam54

6 ports use 2 ports that open at higher rpms for more duration
they close at low rpms so they dont hurt torque

rotary VTEC if you will

fatboy7

In stock form the 6-port motors make more power than the 4-port ones, and have a more useable powerband. Unfortunately, the 6-port motors are difficult to port, and the benfit of porting is less than the 4-port engines. In short, the 4-ports more power with porting than the 6-ports.

xenophobe

do the ports open with vaccum or are they opened mechanicly with rpm?

xenophobe

so if i wanted to make more power then stock i would be better off finding a 4 port motor?

now the question is were there 6 port 12a's? (so i know to try and avoid them if there are)

wwilliam54

backpressure

1stgen4life

iTrader: (1)

All 12a engines were four port I believe. If you get a 6 port 13b, you can swap the housings with those from a 12a. That way you can have a four port 13b that is ready to be street ported, or any other kind of porting you want. Correct me everybody if I'm wrong.

wwilliam54

has to be pre 86 13b houseings

two79rx7's

So you are saying that a 13 B motor with pre 86 housings (4 port design ) compaired to a 6 port 13B, once each is ported; the 4 port design will make more power and tourque and have a better power band assuming good engine management, intake and exhaust

is not the 13B 60 port designn better to start with? and in the end you will getr more out of it?

wwilliam54

no 84 -91 n/a 13b's are all 6 port
turbos are 4 port

the prefered way to make a 4 port is to take 12a plates and 84/85 13b rotor housings

4 ports generally have more top end, but low end suffers

the 6 ports dont go as high, but are more drivable and hvae more low end

two79rx7's

If I am right first the 84 -85 13 B from the gslse is a 4 port, that was said above too.

what is the advantage of using 12a plates?

the 90 13B 6 port puts out about 165 or so Horse power stock compaired to 135 HP for the 4 port 13B gsl se motor

so you are saying the 4 port once ported well will have a higher peak output power at the top end than a 6 port could ever have once ported well too?

wwilliam54

something like that

and 12a plates are cheap