aarons

the 86-88 turbo
and the 89-91 turbo

kenn_chan

First Arrons,

welcome to the club. as a new member you probably are not aware of the archives, search features and the FAQ. please use these as they are a great resource for finding out all manner of great things about the rotary engine that mazda uses as the power plant for many of there cars,
(including our beloved 1st Gen Series) Many of the members might not be quite so nice in how they point out the basics, so next time try and search first.

that being said

86-88 13bT (also called series 4, or S4)

first version of the 13bt, has weaker rear housings, as well as useing a mechanical oil metering pump (OMP) it also has lower compression rotors that have the thickest casting of the turboed 13b engines

89-91 13bT (also called the series 5 or S5)

second version of the 13bT it has an improved rear housing (reists cracking better)
slightly higher compresion ratioo rotors, electronic OMP and and host of other small detail changes. it is generally prefered from a power making standpoint as it will hold together a little better than the S-4 it also made a little more HP than the earlier version.

I suggest you search for the 13bt S4 and or the 13bt S5 this will get you many hits and it will take a couple of days to sort out the chaff from the good info, but thats half of the fun.

kenn

trochoid

iTrader: (6)

You might try the second gen section, starting with the stickies at the top, then search the 2nd gen forum. Kenn summed up the basics, quite well as usual.

Many on the 1st gen forum are not overly familiar with the 2nd gen engines. There are a few nortable exceptions though. Steve84GS is the go to guy for the S5's in 1st gen bodies.

Hyper4mance2k

iTrader: (40)

http://fc3spro.com/main.html