i have 13b 6port engine thats street ported and running a holley 600cfm carb. for some reason the guy that did my engine ( Ken from rapid rotary in washington state) swapped out my gsl-se rotors for 89 gtu rotos.....how would that benefit me if there are any, and what are the specs on both the SE's rotors and GTU...compression/weight

 

S5 rotors are lighter,have machined recesses and higher compression ratios.They are commonly known as the best N/A rotors going,besides the Renesis.
S5 is 9.7:1, verses the GSL-SE at 9.4:1
S5 is 9.54lbs each, verses the GSL-SE at 11.58lbs

There is a noted concern with swapping FC and FB rotors/housings due to minor changes in the shape of the rotor housing after 86.Plenty of people have done it sucessfully,even though companies like Racing Beat say they dont/wont recommend it.

 

S5 rotors are lighter, there is a difference in comp, but I don't remember what it is. S5 rotors seem to be the preffered ones, even with a TII swap.

Oops, Steve beat me and with his usuall better info too.

 

s5na rotors even in my t2. good call on the builder

 

The only actual change in the housing was the positioning of the spark plugs. they were a littlebit lowerin the housing, noteably the trailing. Also you haven't been keeping up. The Renisis rotors aren't any good at all. You see Mazda used a shorter apex seal and wider grove to allow the apex seal to wobble and get a tighter seal and better compression on the renisis. Sounds good until you figure mileage and wear into the equasion. The extra movement of the apex seal is causing premature wear on the rotors apex seal grove and causing apex seal failures. Hense Mazda's current engine recall on the Rx-8. :smiley_12

 

HELL YEAH !!!!!! so all i need now is my bridgeported 12a irons and i will feel as if i would have one BAD *** n/a.......any one have some or know where i can order some good ones

 

rodger that. Since you're in japan, I'd try RE Amemiya. LOL! $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

 

The FC rotors also have 2mm apex seals compared to 3mm for the GSL-SE. 2mm are better in an na application as you dont need to worry about detonation. They seal better and cause less wear on the housings.