I searched for some info but it seems like this had came up before but no ones ever tried it. I think rx7 turbo would be good on stock d15b since d15 has very low redline, and rx7 turbo should kick in quick since its for 1.3l engine. Am i going retarded or smart? would it even work at all? and what junky turbo would be the best for 1.5? TIA

 

Rotaries make a lot of exhaust gas. I don't have many details about the Hitachi unit from the Turbo II cars, which is what I think you are talking about. I do know the compressor wheel/housing was designed expressly for the excessively pulsed nature of rotary exhaust.

In some racing classes, rotaries are grouped with cars twice their displacement. Make of that what you will, I don't think it's good enough for a direct comparison.

BTW, can I get pics of the Hitachi's turbine, if you have it on hand?