I'm an ASE certified Master Tech, been on a bunch of automotive forums, all under the same screen name. We got a Miata for my fiancee about a year ago, we are the 3rd owners, it has 190K on it. It still runs good, but I'm trying to decide whether to replace the engine and rebuild the old one, or buy and rebuild a used one then swap it, but definitely want to do a nice mild turbo setup on it for her. Also looking at doing a much nastier one for myself. I have a 93 S10 that I've done a (430 hp) 6 liter/700R4 swap in, (does 12.20s on street tires), and I also use it to tow my twin turbo Chevy Vega drag race car, which goes mid 9s in the 1/4 mile (so far, better times yet to come). What I want for myself is a "modern day AC Cobra" with even better performance. Looking forward to learning about these great little cars, and perhaps sharing some of my nearly 4 decades of automotive experience with other members.
I could almost see a turboed 6 cylinder swap on her car later on, always liked the 60° packages, a 2.8 or 3.1 Chevy with a 5 or 6 speed would be pretty cool. But for mine, the LS is probably going to get the nod, and most likely turboed as well. Lots of guys on theturboforums.com building 5.3s and 6.0s, and my boss has a 2000 5.3 with 540,000 miles on it, and still going strong, I'll probably inherit that one day and rebuild it. I think there's probably about as much room under the hood of a Miata as there is under the hood of my Vega.
I'm a big believer in fat rubber. I built that kart a few years ago, it's a Suzuki RM250 dirt bike motor, with the biggest regular kart tires they make. Kart itself weighs 160 lbs. Specs say the motor makes ~43 hp @ 9600 rpm. It has pulled the front wheels up on a road coarse coming out of a turn.
Obviously, differerent people are in to different things. Evident by the #StanceNation#ClubRicer#ILikeBuyingTiresEvery15Mil es.
For me personally, the miata is not the car I would want to build big power with. The main limitation being tires. The widest 15" street tire currently available for the miata is a 225. You can put wider rubber underneath it, but you're talking r-comps at that point. And for what you would need, not even flares would be enough. But I suppose some people like fenderless exposed tires. I don't see myself spending big$ on a track only car. I'd much rather have a weekend car, built up fast, uncomfortable, etc. that I can still drive on the street, go to car shows, race civics with stuffed animals hanging from their ginormous tow hooks, etc. Again, just speaking with regards to my personal goals. If this is seriously your goal, and you're going to spend 20/30/40k on a turbo LS build, just keep things like this in mind. If you're going to have grip, you're going to buy r-comps regularly. REGULARLY.
Tl;Dr: Buy an FD RX-7.
Sidenote branching off of the hondas: I pulled up next to an integra at the gas station after getting off the interstate tuning. While making a few changes to the tune sitting in this parking spot, the integra starts revving up his car, and just holding it on the ******* rev limiter. WAMMMBAMMMBAMMMBAMMMMBAMMMBAMMM. Sounded terrible. Big **** eating grin on his face. And so my friend looks at me, and just gives me the look. Queue spark-cut 2step. It's like 2am, so dark enough to see the HUGE flames out the tailpipe. Guys face instantly sinks. Man was it funny.
Punk kid next door goes through crappy used cars like crazy and always holds them on the rev limiter sitting in the yard. Civic, Neon, Jeep, Crown Vic, pickup truck, they all get held on the limiter. I don't get it.
OP, you don't need a great bigass engine to go fast in these cars because they aren't fat pigs. You can go 12.20s with high 2xx whp if you prep the car right.
And did you really mention the 2.8 3.1 engines? You must have missed the LFX swap threads or don't know what the LFX is...
Much fun can be had with them.