I've been wondering this for a long time. Is it possible to engine swap a standard 323f BA 1.5 to use an MX-5's 1.8? Would the gearbox be able to handle the power if I was to turbo the engine in search of more power? More importantly, is it an easy swap, if it can be done? If not, what other potential easy swaps can you recommend? I'd love to make a 323f BA faster if I am to buy one but unfortunately 1.8s are getting extremely rare these days. Cheers.

Is it possible? Yes, the 1.5 gearbox will bolt right up (you'll need to use the 1.5 clutch too), though you'll face some difficulties with coolant lines from the head to the heater matrix, and you'll need to make up a blanking plate or fit a freeze plug where the MX5 thermostat was. You'll also need to find a set of 1.8 BA engine mounts...

Would the gearbox hold up to the power of turboing it? No You might be alright for 150-175bhp but after that you'll be pushing it! The older 1.8 G series box is a bit stronger but even then, must past 200bhp you'll risk stripping 3rd gear or snapping the shafts and casing.

Is it an easy swap? Relatively, if you know what you're doing - wiring will be the biggest headache if you haven't got a 1.8 BA donor.

Potential easy swaps: 1.8 BA - that's the full list, anything else will be hard work, and you'll need a running and driving donor car anyway... which leads to the question, why not just use that car?