Andy's NC Miata: How To Make 300 Horsepower In 3 Not-So-Easy Steps

“After five years of ownership, I’ve learned these cars only last when they’re basically stock,” Andy began.

Some of Andy Boskovic’s friend suggested he keep tracking his E92 M3, but it just wasn’t exciting him any longer. “I’d tried a few light cars, and I liked how playful they were,” he recalled. “No matter how much power a car has, if it’s lightweight, it will always be fun,” he said. Plus, the cost of consumables and its heft kept him from relaxing. Careful not to break the bank, he started looking for something svelte, simple, and reliable.

Because of his size and his cost constraints, he bought a mildly prepped third-generation (NC) Mazda Miata. For a third-gen Miata with Megan Racing coilovers, Hotchkis swaybars, and a factory hardtop, a mere five thousand was money well spent.

If there was one unforeseen problem at this point, it was that Andy did not know quite how limited the NC aftermarket was back in 2018, but, thankfully, this car was quick and reliable enough to not need to. The car ran well in stockish trim, and no real changes were necessary for the first two years of tracking.

The factory NC brakes are stellar: Castrol fluid, RB 2-piece rotors, and Hawk DTC-70 pads provided stable, reassuring confidence.

After getting to terms with the car, he could diagnose its few weak points. More confidence on the brakes meant harder laps and more aggressive corner entries, and those highlighted the one glaring handling issue.

Though fun, the car was a little too loose to be truly quick, and this was clearest in the faster corners. “The short wheelbase makes this car oversteer in Riverside,” he started. He first softened the rear bar, then removed it entirely. “I picked up a little understeer when I removed the rear bar, but I gained 1.3 seconds the next session on the same tires,” Andy added.

Another Half-Liter Can’t Hurt

After two years of trouble-free track days, the engine began to knock. Intent on keeping his costs low, he decided to try the 2.5-liter MZR alternative. This particular motor came from a Ford Fusion — a $200 find at his local junkyard that swapped into his car with minimal modification.

Swapping the 2.5 into the NC’s engine bay requires transferring oil pan and valve cover from the 2.0-liter to the 2.5-liter, grinding the front cover engine mount plate to allow the belt to spin without rubbing, and changing one pigtail for camshaft position sensor. Everything else stays the same; the whole harness, ECU, engine mounts work. What’s more, the transmission is direct fit.

It’s a good thing the swap was simple, because the excitement didn’t last long. After just three track days, the engine blew. Andy believes it was a lousy online tune which caused the engine to run too rich. Because he hadn’t installed any A/F meters, he’d been totally unaware of his pistons were getting washed over the first few months.

This setback didn’t deter him. In just a few weeks, Andy grabbed a new motor — one with which he would try a different approach.

Being designed for an SUV, the 2.5 MZR was never really designed to rev. The motor feels genuinely torquey—almost VQ-like—in the midrange, and calling the top-end lackluster would be generous. Extra cubes do help the car feel livelier in slower corners, but the disappointing final few thousand revs warranted a major change — even if the motor was never intended to buzz too high. With a set of Esslinger camshafts and a little headwork to enable 7,500 revs, he extended that top end to a point where things felt S2000-ish.

Another half-liter makes makes life significantly easier.

The 190 horsepower the new lump came along with a few complimentary additions to turn a mild street car into something focused and trailered. Version 2.0 sported a stiff set of Feals, a full cage, and a lot of unsightly bare metal. The stripping process brought the Miata’s weight down to 2,330 pounds, which is not much heavier than a Spec Miata, but with an additional 70 horsepower and 100 lb-ft of torque, those power improvements made the Miata much more versatile.

Compliance is Key in Southern California

The 13K/10K spring rates didn’t suit the bumpier tracks he frequented, so he consulted Karcepts, who tuned the NC cars which ran in the Playboy Cup from 2008-2013, suggested he try a softer setup. They supplied him with some MCS 1-ways, which came along with 10K and 7K springs. The improved compliance netted him a whole second on the same set of tires. Clearly, he was on the right track, though the setup was far from perfect.

In an attempt to try and minimize some of the car’s tendency to oversteer in high-speed corners, Andy cranked the front dampers and left the rears on the softer side. “It rotated when you wanted it to and the rear stayed stable. Still, when the rear finally let go, it was not very progressive.”

“I was never that interested in running aero because I didn’t like that Fast and Furious-look, but I couldn’t accept the snappiness at the rear, so I tried a wing.”

Following the first on-track session with Racebred Component’s 4” front splitter kit and their GT rear wing, Andy forgot entirely about looking like an attention-seeker. The aero bump immediately chopped 2.4 seconds off his previous best at Buttonwillow. Other than adding the wings, nothing else had been done to the car.

The unfortunate byproduct of greater stability in the fast stuff was a smidgen of push. Not so much to keep him from attacking, but just enough to feel the Miata was no longer the playful, adjustable thing it used to be. Cleverly, Andy chopped two holes in his front fenders and topped them with a set of Cockroach Concept louvers. These relieved pressure from the fender wells, improved front downforce, and helped the car regain its natural pointiness — now tempered by the rear wing. It’s extremely neutral in both fast and slow corners, and it’s still soft enough to soak up big bumps.

The performance of the front relative to the rear encouraged Andy to see if he could further strengthen the car at turn-in. With a five-inch splitter and front spats from Racebred, the front end was electric, but more importantly, he could still keep the car balanced aerodynamically, though that required doing something many Miata owners might be hesitant to do.

Trim Fast

Without much torque, Miatas have to avoid as much drag as possible, hence the preference among many owners to run only as much wing angle as necessary. He was conscious of overslowing the car on the straights, but he needed a more neutral balance to push hard. By increasing the angle of attack at the rear wing, he found a confidence-inspiring aero balance that, as he learned, improved the car’s cornering performance enough to incur a little drag.

For someone accustomed to trimming his Miata out as much as necessary, this was a shock finding. “I was losing about three miles an hour on the straights, but the car was so much faster in the corners that I saw a net benefit to this high-downforce configuration.”

Content with the aerodynamic and suspension settings, Andy started on the one area he was reluctant to try. Between a bad tune and his habit of revving the tits off his motors, he went through three engines —one 2.0 and two 2.5s — in the four years he’d had the car. Still, seeing a Mustang or Porsche walk away towards Sunset was a source of real irritation, so he decided to turbocharge his MZR.

Unfortunately, the aftermarket hasn’t provided NC owners with many different turbocharging methods to try. Yes, the MZR has been turbocharged for competition use, but the AER-built motor found in IMSA prototypes and Indy Lights cars is a far cry from the factory 2.5-liter.

Long story short, the turbocharging process has been, as Andy put it, “a world of shit.” The problems with overheating and oil starvation killed one motor quickly, and the current engine, built to maximize torque and keep the revs reasonably low, is still getting the bugs worked out.

However, parking lot tests have demonstrated real grunt, tractability, and promise. With a standalone ECU, a reinforced gear hub in the fragile gearbox, and a smaller wastegate spring, he plans to have a dependable 260 horsepower from 3,500 - 6,500 revs.

“I believe revving the 2.5-liter engine to 7,500 shortens the lifespan to forty track days or so. The turbocharged engine doesn’t need the same revs to make power. If you cap the revs at 6,500 and power around 260, I think it could last. I’m not betting anything on it, though,” he laughed.

Sam's Semi-OE Turbo Miata: Taking Advantage of Pre-COVID Pricing

I try to fight the occasional sting of envy when I walk through the Speed SF pits. One particular car made me want to crawl up inside a hole and cry—this immaculate ‘00 Miata. I’ve already bought and sold one NB Miata—a car I wasn’t completely enamored with, but after learning that Sam Tsui was able to get this car with such an incredible collection of parts for the 2022 price of a rough NB without a hardtop, I was kicking myself for not buying one a little earlier.

A couple years prior to the pandemic, Sam helped define the term “pre-COVID prices.” He’d had some fun over the prior five years in a Fiat 500 Abarth, but the high center of gravity, intrusive nanny systems, and cost of performance parts were too much after some time. He’d grown somewhat comfortable with the car, but its odd behavior in fast transitions kept him from pushing it harder. As he was starting to push hard on a regular basis as a Lemons racer, he started searching for a rawer car. Within a month, he came up on the steal of the decade.

The low costs of a Miata drew him to seek out a lightly modified NA or NB. “I wasn’t looking for something that had been pretty much completed, but that’s just how it worked out,” Sam said. At a barbecue, he learned of a sorted track car his friend was looking to sell. This car had pretty much what any track-oriented Miata needed, an immaculate exterior, and it had a special motor fitted.

The trials and tribulations of turbo Miata ownership are nothing new, but it seems that sticking to a semi-OEM route can keep the headaches to a minimum. What Sam’s friend had done was swap the entire powertrain from a Mazdaspeed Miata—the 1.8-liter turbo engine, six-speed gearbox, rear axle, and limited-slip differential. With a few bolt-on parts from Flyin’ Miata and a good tune on a standalone Hydra Nemesis EMS, the engine makes a healthy 210 horsepower and 200 lb-ft of torque. Best of all, that torque came on strong at 3,000 rpm. That really changes the driving experience. Now, the throttle is squeezed and not pounded like a veal cutlet.

It looks nearly factory because it is.

Having only a set of 15x7” Avanti Storm S1 wrapped in 205s to put that power down, Sam had to recalibrate his right foot pretty quickly lest he spin in a slow corner. “The Fiat was easier to drive; I could floor it in hairpins and it would hook without any wheelhop. With the Miata, I have to squeeze the throttle carefully in second and sometimes third gear.”

As he was looking for that added feeling of connection, he made sure to replace all the tired rubber bushings with polyurethane items. In conjunction with a stiff set of Megan Racing coilovers, the reduced slop helped him achieve a handling balance that verged on oversteer in most places. In fact, the Miata will try to spin if it’s thrown into the corner, so Sam learned to slow his steering rates down a little. Much more than the Fiat, the Miata is eager to rotate.

And stop. The brakes were replaced with the Flyin’ Miata Little Big Brake kit, which consists of Wilwood four and two-pot calipers clamping OEM rotors. For a car this light, the stock rotors are more than sufficient. On a set of 200-TW tires, the braking this 2,450-pound car is capable of will leave most folks with their mouth agape.

A basic lightweight flywheel aFactory ABS, a hard top, and a good amount of safety equipment help Sam push with confidence.

For how little he got this car for, you’d expect there to be a stripped interior, rust, or some other catch. I’m sorry to say, this car has very little wrong with it. Cosmetically, it’s about as nice as a track car should be. The interior is all in place, and there weren’t any hack cuts in the carpet to fit the rollbar, either. The hardtop is painted nicely, the wheel fitment is subtle but noticeable, and the generally understated appearance doesn't scream regularly driven track toy.

For a turbo Miata, it’s pretty robust. Sam has run nearly twenty track days with the car on the stock radiator and fan setup, only aided by a Flyin’ Miata FMIC, and it still runs cool. However, he has to watch the water temp when the ambient is pushing 100.

Though it’s been tuned to such a high standard and really doesn’t need much else, Sam left his mark on it. In addition to swapping out the bushings, he fitted the interior with an OMP wheel, a Hard Dog rollbar/harness bar, and a RaceDirect.com 6-point harness. Just a few tweaks, but enough to make it feel like it’s his. Without a doubt, this no-stone-unturned track car doesn’t need much more.