pandabreads

Hey all,

Just joined the site and ready to begin my journey through all the stickies and FAQ.

I have a NB Miata 1.8/5MT (1999) and am currently in the process of turning it into an AutoX/hooning machine.

The engine is currently sitting at the machine shop waiting on the new rods/pistons/bearings.

I just ordered a set of Wiseco 83.5mm 8.5:1 pistons, Manley H-Beam rods, and some ACL race bearings.

Honestly, I'm not really sure what my end goal is with HP and TQ at this point. Probably around 300-400HP range unless I'm going to be in trouble with drivetrain breaking etc. This is where the journey into the FAQ comes into play!

Anyway, Just wanted to make my first n00b post and say hello.

Joe Perez

iTrader: (8)

Welcome aboard.

For reference, 300HP is an absolutely insane amount of power in a Miata. The stock 5 speed transmission is unlikely to survive more than a few miles at that power level, assuming you can maintain traction. The later 6 speed gearboxes are slightly tougher, but 300HP is approaching their limit.

400HP on a Mazda 4 cyl block would put you into godlike territory. The only people I know doing those numbers (reliably) are running Chevy LS series V8 engines, with drivetrains to match.

For reference, 200-250 HP in a 2,300 lb car is surprisingly fast, and you won't tire of it easily.

pandabreads

Oh wow - good info! Shows how much i know at this point... I'm perfectly fine with 200-250 at this point with the car as well. I was just ballparking based on previous 4CYL turbo setups I've been around.

Schuyler

iTrader: (1)

https://www.miataturbo.net/build-thr...ild-you-61522/

Will give you an appreciation for what that kind of power takes.

Braineack

iTrader: (62)

Welcome, pandabreads!

Joe Perez

iTrader: (8)

And by 4 cyl, you mean 4 rotor, correct?

In all seriousness, a Miata is not a heavy car. At a hair over 2,300 lbs, that '99 is easily 600-1000 lbs lighter than most other 4-bangers commonly considered to be "fast" (Lancer Evo, WRX, Integra / TSX, Focus, Golf, etc), and of course part of that lightness comes from being equipped with a transmission and differential that you can pick up with one hand.


200 HP / 200 ft.lbs was a magic number for years in the Miata world, though of course with modern engine management there are plenty of 225-250 HP Miatas being driven daily on the street. Beyond 250 HP, however, things start to get a bit dicey. There are certainly folks doing it, many of whom are on this forum, but it's not exactly a recipe for reliability.

Since you've already torn down the engine and bought all the expensive bits, you might as well go ahead and put it together. Off-boost performance is going to be a tad lackluster with such a low CR, but it does buy you headroom to play.


Forgetting about anything else for the moment, what are your plans concerning engine management (ECU, injectors, fuel system)? This seems to be the sort of thing that a lot of folks put off as an afterthought, but I far prefer to get it taken care of up front, before the turbo is even out of the box.

pandabreads

I'm still doing the research on ECU/Tuning and even which turbo to go with at this point. It seems the Megasquirt ECU is quite popular... I have no intention to try and cut corners in the ECU/Fuel department. Previous builds have taught me many important lessons regarding these components! I actually didn't even plan on going turbo until yesterday. The machine shop suggested I get pistons .10 over and I just basically decided if I'm going to buy internals, why not buy the good stuff!