I am looking to build a 1.8L vvt that i tore out of an NB for my 1992 miata. I was hoping to build it to about 200-250 whp with a turbo. The goal for it is to be more reliable that the old neglected 1.6L that's already in it, but also have some fun and more power.
I will be building as the age of the 1.6 grows older and use that time to reenforce the structure of the car, IE roll cage and safety mods.
I'm new to the modifications of this car and have only done a lot of maintenance on the car such as a manual swap and redoing the timing (about 5 times fml). I have never worked on a turbo before and was also hoping to get into with this.
I've heard that the bottom end can hold my power goal but I'm not sure if that's true.
I am going to redo the rod bearings and seals to refresh the old 1.8 but should I replace the pistons and rods? If no how can i gauge the health of the cylinder walls. Are piston rings worth redoing while I'm in there?
I'm going to be compiling a parts list hopefully too. Please let me know if I'm being dumb.
I appreciate the feedback!

 

These are all great questions that have never been asked or answered before. It really is a mystery if piston rings should be replaced during a rebuild, so hopefully someone with experience chimes in.

 

I'm not one with experience, but you may as well just throw in some beefier rods, and pistons since you're going through all of the trouble to refresh the motor lol

 

A stock VVT 1.8 L can give you what you want in a 200-250 hp range. What to do in the bottom end and head depends on the condition of the motor now, and what boost you plan to run.
What compression does it have, what are the leak down values? Does it blow any smoke on accel or decell? How many miles?

Once you open the bottom end, the "do it while I'm in there" syndrome raises the project size pretty quickly. Bearings, to rings, to boring the cylinders out because they are worn or no longer round, to new over size pistons to match the bore, rods, and then on to the head; Deck head and block, valve grind and so on. It is all worth it, but is it really needed to achieve your goal?

If you have decent compression, modest leakdown, and moderate mileage I would leave the engine alone, and add the turbo, learn how to do that, learn how to wire it, run the after market ecu that you will need, And get the car running properly.
Once done all that, decide how much you want to do to upgrade and refurbish the engine.

Or dive in, do it all, and then add the turbo. There are so many in between stages you could work to, too.
As Simba was hinting, having found the forum, dig in and read build threads, engine mod threads, turbo how to's, so you can better formulate questions that can have more specific answers.