Ok i know this has been asked before, but i cant seem to bring up any straight answers on it so i figured id ask again.
So i have an 87 turbo2, it has a medium street port, 680cc injectors, Fd fuel pump, fmic, full turbo back exhaust. Its currently running on the stock ecu and boost but i plan on going rtek soon.

My question is, whats the biggest turbo i can run with the stock manifold? Im not looking for huge gains just yet since its my DD, but i have alot of shaft play in my current turbo so i figured id upgrade a lil bit. Im gonna be building a big turbo setup over the summer so i just want something i can bolt up to the stock manifold for now that'll maybe give me a lil more boost.

 

The engine will not run properly with 680cc injectors and the stock ECU.

If you want to stick with the stock manifold, then you can get your current turbo rebuilt and upgraded for pretty cheap.
BNR Supercars - Bryan Nickell's Rotary Supercars - Mazda RX-7 2nd Generation (1987-1991)

 

the flange is proprietary Mazda so nothing will fit. its not a standard flange which sucks.

with your mod list i dont see a aftermarket manifold and downpipe being our of the question. it doesnt sound like you are trying to stay stock or keep the stock look at all.




i should also say you can do something like this to your factory turbo also if you want. you have to mix and match housings/compressors etc though.


https://www.rx7club.com/2nd-generati...egate-1058395/

 

The car does run rich, and there only 680cc secondaries. It idles good and i havent had any problems with it running wise at all. I also have a wideband so i can keep track of the a/r's.
I was checking out my turbo today and it looks like its some kind of hybrid already, the compressor housing has no markings on it and it looks different from any ive seen before. Is there any way to know what exactly it is? Its still the stock turbine housing though.

And no im not trying to stay stock at all, just looking for a cheap upgrade while im building my big turbo stuff.

 

If you want to stick with the s4 t2 turbo, the wastegate flapper door needs to be changed and the stock hole ported out like bnr does