Hello everyone,
My my name is Ivan and in March I recently purchased a 1990 Mazda RX-7 NA and enjoyed it over the summer but it lacks power so over the winter time I would like to convert it to turbo but I don't know what the most cost-efficient way is. Some of the rotary people I talked to say to just do a full turbo 2 swap but I feel like that is more work when I already have a motor. So my question is, would it be more cost efficient to by a manifold, turbo, ECU, fuel pump, and an intercooler, get it tuned and call it a day or by a turbo 2 13B? My only thing is that I feel like if I buy a turbo 2 13B either way I'm going to have to open up the turbo 2 13b to refresh it so why don't I just open up my NA13B and refresh it and then put a turbo on it. I'm very new to the rotary scene and would appreciate any comments and advice. Thanks in advance.

 

welcome to the board, Ivan.

here are my thoughts on your questions:

1. your S5 N/A engine is completely different from an OEM T2 engine. the main differences are the number of intake ports (6 vs. 4), the rotors (different compressions - 9.7 vs. 9.0) and exhaust ports (the N/A has diffusers in place). there are some other differences, too, but those are the ones that probably matter most. you can surely work around the differences, but you are pretty much stuck with them if you keep your N/A block.

2. how you turbocharge the car is totally up to you - either way will work - but just keep in mind that the T2 engine was designed with a turbo whereas the N/A was not, so depending on how far you plan to take this, those differences will become more and more of a factor, especially when tuning it. i have seen people turbocharge N/A engines in a variety of ways, and even run them with factory ECUs, but at this stage of the game (30 years down the line) i'm not sure if i would recommend doing it that way to anyone, and especially not to someone that is "new to the rotary scene." i would say at bare minimum do the complete T2 swap ( ECU and wiring mods included), but realistically, plan to include some sort of standalone EMS to tune.

3. you're going to be looking at a lot of work either way, because you will need to make things you'll need for a turbo setup if you proceed without the T2 engine. you could get some bolt-on T2 parts to help (front cover, water pump housing, oil pump), but i haven't been seeing T2 parts as plentiful as i once did, maybe your experience might be different. outside of the things you could bolt on to help with the addition of a turbo, you'll need to fabricate or have someone do it for you.

4. budget is a fair concern, because you'd have to acquire a turbo engine in addition to a possible rebuild/refresh. however, i suppose you could sell your original engine to help defray the added cost.

alternative plans ...

realistically, how much power (ballpark) are you looking to make?

if it is a case where you want to achieve a relatively modest increase, then you can just modify the N/A engine - EMS, semi-ITB intake, exhaust and flywheel should get you a nice, fast and reliable car. of course, you won't have the turbo torque, but it would be fun. if you want more at some point, porting would still be on the table. just something to consider.