Hey! I'm starting with my turbo miata build, i currently have a really nice 1991 1.6l miata. The main question is, what would be better, staying with my 1.6, buying forged internals + changing the drivetrain to the 1.8l one, and than turboing the thing, or just swapping the engine out for a 1.8l with its drive train and than turboing it. The money that i would save on staying with the 1.6l could be used to build it from ground up on forged internals, so my question is what would you recomend? In my opinion a fully built 1.6 would be much more efficient than a stock 1.8l turbo. In advance, 1.8l engines here in poland are quite expensive, forged internals for a 1.6 would be approx the same cost as the swapp. Im looking for +/- 300bhp.

 

I would go 1.8 and try to find an engine. Maybe even here in Germany? Got mine for 150€ and it was fine (built it none the less).

Built 1.6 is not the common route here, but there are several people happy with it. Do not go for a big turbo, it will be all top end with a big blower.
GT2560 or a TD04 would be my choice for 250whp on a 1.6 with cost in mind. There are new Garrett 2560's for 750€ from germany atm.

You also need a new diff and driveshafts. The small 1.6 diff is probably going to explode in no time

 

It's not just a question of the displacement of the block. The 1999-up 1.8 cylinder head and intake manifold flow much better and will make more power everywhere. We are sourcing many 1.8 engines from England for reasonable prices. There are vendors here on the forum that ship them. Rear differentials and axles, too.