i heard the earlier model TII's around 400 and later were 500. im proably gonna get the earlier model becaues its cheaper, and the first thing i wanna do is rebuild and bulletproof the engine. if i ever get this much power i want to know my engine can handle it, what should i do while i am having the engine rebuilt to make it stronger and capable of 450+?

there are numerous things, like coolant and oil passage upgrades, and to the extreme extra dowel pins. Check with your rebuilder.

are the later model rotors interchangable with the earlier models?

i think so, but im not sure, since i have no experience with rebuilding.

Yes, but you have to use the corresponding front and rear counterweights.

You can have the rotors milled to accept 3mm apex seals in place of the 2mm ones.

They are the same between series. Series 4 > 5 will swap but as Ace said you have to change the counterweight.



The different series are of different weights and compression. Series 5 (89-91) is the best N/A motor (Next to the next RX-8).



2nd Gen 13B's are totally different from the early 13B's (COSMO, RX4, REPU).

the S4 Tii engines will handle more boost cuz dey got the lower compression rotors, when u rebuild be sure to port the mofos, a bridgeport would be good, but i recommend a big streetport (for bridgeport most of the power is at hi RPM's) DON'T get 3mm apex, that's old technology, ppl only use 3mm's if the apex groove is really worn, 2mm Ceramic apex are the best (if u can afford em)

Wouldn't it be the same if you could boost more and if the compression was higher? Even if you could boost more with the earlier motors (aka GTR), it would only be very little. I believe compression of the later model (aka GTX) motors will bring the same gains as higher boost. All I know is that the later model motors were more reinforced and the rotors were lighter as well as higher compression. There are many advantages to using the GTX motors compared to the GTR. There is a site with great info, breaking down each of the 13B's built from the 13bt GTR's to 13bt GTX's to the 13Brew's.



Here is the link to the site:

http://my.engr.ucdavis.edu/~pko/13BTvs13BREW.html

some of what he is says is correct. low compression rotors will allow for more boost on poor tuning. a good tuner can make alot of power in a high boost high compression engine and not blowup https://www.nopistons.com/forums/pub...DIR#>/wink.png i don't agree with the ceramic apex seals though. stock mazda seems to be fine. everyone is entitled to an opinion though