NlGHTTRAIN

Hi everyone, I’ve always wanted a FC Rx7 and I recently got a rolling 1989 FC Coupe shell No rust but a pretty haggard interior, my over all end goal plans for this build is a street legal drift car around 300-400HP and try to save money at all cost of course. I was dead set on a V8 swap and honestly know nothing about rotarys. but since im on a budget and want it street legal maybe the rotary is just what i want. so if I do rotary how much $$ could is be as compared to say a ls3 or a V6? What are my rotary options? I’m not big on HP at the Start But want potential of course and some reliability would be nice.

WondrousBread

13BT will get you to the hp figure you want, but it isn't super cheap. Probably still cheaper than an LS swap though. You can look up the cost of running 13BT engines near you to get an idea of the cost. You don't mention whether the car is an NA shell or T2. If it's an NA shell, you'll also need the T2 transmission. After that either a custom driveshaft to the NA rear end (probably a bad idea for a drift car that is going to be under a lot of strain) or a T2 driveshaft, diff and half-shafts.

Also keep in mind that a stock T2 makes ~180hp, and the stock turbo typically doesn't take people much farther than 280 (or so I've heard). This guide here should give you an idea of what it takes to get to higher power levels.

Otherwise you can do a 13B-REW swap from a 3rd gen. Those engines are more stout AND parts are still available. However it is more costly and not a straightforward swap (engine mounts in different places, harness isn't long enough for stock ECU, stock turbo system is complicated). Look up the build thread in this section called "The Blue Car", I'm pretty sure j9fd3s gives a basic rundown of what is required there. Plus you can see pictures of it in his car. You still won't get to the figure you're mentioning with an engine swap alone, but you'll be closer and have more power potential later down the road.

As to reliability, the #1 biggest factor for that is maintenance and good tuning. Maintenance is tough at this point since most of these cars are on their 2nd or 3rd owners at least and engines on their own are a bit of a black box. So try and get an engine that has had it's compression tested. Once you have an engine make sure to change the oil on time, the coolant once per year (longer if using Mazda long-life or similar), and a bit of premix in the gasoline is good insurance. Also consider that these engines are pretty old, so make sure to replace the vacuum lines and check the gaskets on the intake. Idle and driveability problems are almost always caused by bad grounds or intake leaks.

Don't perform modifications and then drive without a tune. Don't upgrade the turbo and not upgrade the fuel system to match. Don't use bandaids like those fuel-cut-delete boxes. Don't run it low on oil (check it every so often to be sure). Research every modification thoroughly beforehand. If you follow this advice it goes a long way.