Turbocharging an NB Miata for Super Touring 4 Competition

Seven years into racing and George Koustoumbardis has seen more than some have with two decades invested. Despite criticism from envious peers and the financial limitations of most teens, he keeps progressing at a rate that would burn out most folks. Being young certainly has its perks, but there’s no doubt his climb from casual canyon driver to NASA Super Touring 4 contender has been a fairly steep uphill slog.

Money from his high school lifeguarding job helped him pick up a basic NB Miata his junior year. Being a person with reasonably high standards, Koustoumbardis wasn’t content with your garden-variety NB track toy and immediately sought more power.

Forget Momentum 

He went to Trackspeed Engineering for a one of its turbo kits. The BorgWarner EFR the company swears by stands out as one of the foremost turbochargers for the road course due to its titanium aluminide turbine wheel. Little mass means low inertia, so the snail spools as soon as the throttle is teased. Rather than the sort of power delivery most turbo 1.8-liters might provide, this engine behaves more like a big V6.

The kit consists of an EFR 6258 turbocharger, Trackspeed’s log manifold, oil cooler, and radiator. To control the motor, Koustoumbardis installed a Megasquirt MS3. With the stock fuel system, the resulting output was smidge over 200 horsepower and 200 pound-feet of torque at the rear wheels.

If there was one downside to this tested and reliable kit, it was that Koustoumbardis did not have the stock Miata driver’s excuse ready in his quiver. With this power propelling a car weighing 2,300 pounds — and Koustoumbardis himself not adding much to that figure — he had the straightline performance to run with truly quick cars, even at his home track of WeatherTech Raceway Laguna Seca.

Tein coilovers, a Blackbird FabWorx rollbar, a Sparco Evo seat, and 225-section Hankook RS3s wrapping 949 Racing 6UL wheels were all he needed for his first outings in the Miata. Once comfortable in the car, he took it to Buttonwillow for his first attempt at Time Trial. A couple of events later, he was looking for a more intense buzz.

Riding the Wave

That’s the thing with Koustoumbardis. He’s never satisfied for long. After that, with the vigor and enthusiasm of a hungry 22-year-old, he quickly turned things around, increased the power output, fitted 15-inch x 10-inch Konig Dekagrams wheels and 245-section tires, and had TC Design install a nice cage in there.

He fortified the motor with Manley rods, Supertech pistons, ACL bearings, and APR hardware. More fuel was needed if he wanted to increase the boost, Flowforce 980cc injectors, Radium FPR and fuel rail, 6 A/N lines everywhere, and Deatschwerks DW300 pump round out the rest of this E85-capable setup. With a Megasquirt MS3 tying everything together, the motor made a respectable 330 horsepower at the rear wheels in kill mode. Not bad for a 2,420-pound car.

The first outing at COTA went decently, though the second was misery. A gung-ho competitor attempted a high-risk pass on Koustoumbardis and the two collided. Driving all the way back from National Corvette Museum Motorsports Park to San Jose would have been long enough without that sort of frustration. At least he had plenty of time to question the wisdom of his recent investment.

After commiserating with friends, Koustoumbardis got back on the horse. The only way out of the muck was to move in a better direction. After he installed a large splitter and an APR GT250 wing strapped to the trunk lid, he realized he wasn’t far off the ST4 times at Sonoma, and a lightbulb went off.

New Setting Begets a New Character

Besides finding a new direction to head in, Koustoumbardis’ decision to try ST4 forced him to reflect on his first two races and adopt a new attitude to competition. COTA was totally new to him, he didn’t know the competition, and he was frightened somebody would come careening into his car. As a result, his performance was far from stellar, and he really never felt the competitive juices flowing through him like he expected them to.

He decided to take a different approach. Rather than push cautiously as he had before, he would stick his elbows out. This change in mentality incurred a broken wheel, but he didn’t mind. In fact, that seemed like a small price for his Road to Damascus moment.

“It was like something opened up in me,” he said. The challenge of having to gauge drivers in the heat of competition, the improvisation needed, and the way he seemed to be operating at an elevated level was elating. From then on, he wanted to be racing wheel to wheel, regardless of the risks. Running solo and obsessing over tenths no longer held his attention.

That took place before COVID was fully underway, so he kept busy with work and the occasional bit of “close proximity driving” with friends he knew and trusted. When he next seriously considered banging doors, he was well into 2021 and he knew the car needed some work if he was going to make a mark.

Better Mentality, Better Machinery

His approach was sensible. He knew he had to shake off some rust, so there wasn’t much sense in going full-out and buying the best tires available. A successful transition back into competitive motorsport would require cheap tires, a few tries at tracks he knew, and realistic expectations.

There were some mechanical problems, too. The turbo separating from the manifold, the brakes fading midrace, worrying air intake temperatures, and too much understeer. Koustoumbardis realized that if he was going to make a mark in ST4, he couldn’t afford to spend half his time wrenching on a recalcitrant machine.

The overhaul began with replacing the entire front end — minus the subframe. This revealed that the front control arm bushings were completely mangled. Stuffing in new poly bushings resolved the plowing problems.

For the turbocharger issues, he used a little Resbond and high-heat stainless lock nuts. However, the main issue with this recurring separation of the turbo and manifold was not due to locking nuts or the sealant — it was that the way the exhaust was mounted was stressing the turbo studs. Rebuilding and remounting the exhaust to dispersing the load a little more evenly helped relieve the strain on the studs.

The last modification made was a custom front brake kit consisting of Afco F88 calipers, 299 x 32mm rotors, and G-Loc pads.

Knowing he had a solid car underneath him was a relief. So was the knowledge that his conservative spending policy kept him from getting the absolute best from the car. At least he had one excuse ready.

Though turbocharged engines are usually penalized, one upside to running one is the options it offers someone trying to slot into a category with strict BOP rules. He could opt for slightly less power, about 200 at the wheels, if he chose to wear a set of Hoosier slick, or he could spend less on a set of Maxxis RC-1 tires and crank up the boost. He chose less grip and an additional 44 horsepower. Whether this compromise was best for lap times wasn’t so important. He had to get back into fighting shape without putting a dent in his wallet.

As it turned out, he returned to racing, this time in a new category, with a surprisingly strong sense of self-belief. “I felt a weird sort of confidence that weekend. I knew I could do it, but I was still worried I’d psych myself out like I had (earlier). If all went well, I  thought a top-third finish would be possible with my lap times,” Koustoumbardis asserted.

He also had sticker tires underneath him — the first time he’d ever driven competitively on some.

Positive Mental Attitude

It all paid off — Koustoumbardis qualified fifth out of 17 in his first race at Thunderhill, but he wasn’t able to puff his chest out. “My jaw dropped when I saw my position. Then I looked at the times and realized I was the first of the rest — the guys behind were tenths off, but the guys ahead were seconds faster.”

He consoled himself with the knowledge that one of the drivers ahead might flub the start. That said, he was driving on a provisional license and knew a first-corner collision would spoil his chances of getting vetted. On edge and filled with uncertainty, he walked the pits to determine who was on sticker tires and who wasn’t. “The more I knew, the better prepared I would be,” he recalled.

He hopped in and, like a switch had been flipped, his tension suddenly sharpened his focus. Amid the chaos, he caught his rev-limiter just long enough to let a hard charging Jon Burgis past. An overly conservative start, but at least it was clean.

Burgis and Koustoumbardis traded tenths for the first few laps. Halfway through, it was clear that whoever benefited from traffic would come out ahead. A bobble into Turn 9 and an unwitting pick set by a slow Boxster gave Koustoumbardis the opening he needed to reclaim fifth, which he kept with calm, steady driving the remainder of the race. After an amazing battle, he finished where he started.

The second race was less entertaining. A so-so start followed by a great charge and a little luck put him back in fifth, where he was running comfortably until his throttle body failed, though it could’ve been worse; at least it was closed when it broke.

The second weekend at Sonoma started calmly. The nerves he felt before the previous weekend’s races were absent when he got in his car at Sonoma. Actually, he was relaxed well before arriving—so much so he came late and missed practice, which meant qualifying was his first session out. Still, he qualified fifth in a field of 12 — a testament to his comfort with the track.

The race start changed that. The ST4 pack, most of those ahead on Hoosiers, filled his mirrors and had Koustoumbardis looking in four directions simultaneously to avoid contact. As they were squabbling for any available real estate, the differences between a semi-slick and full-on Hoosier became apparent — as did the limitations of his stock Torsen differential.

To make matters worse, he had other classes cramping his style. Whether it be a Spec Miata inadvertently blocking him or a SU prototype appearing out of nowhere, he had more than just in-class E46s to contend with. Koustoumbardis got flustered, began to overdrive, and fell backward. A ninth-place finish wasn’t what he wanted.

Afterward, he sensed he had to dial it back a little for Sunday’s race. He regained his composure, slapped on a newish set of Toyo RRs, and managed to qualify again in fifth.

Calmly, he kept his nose clean, and defended his fifth position valiantly. Deep breathing and a focus on the road ahead helped him keep his composure.

On the drive home, with the sun setting on the wine country hillsides around him, he looked back through his rearview mirror to see the little silver Miata bobbing up and down on the trailer. He’d started with the car seven years earlier, and now, at just 22, he’d moved into ST4 and held his own. And yet, he wanted more. “The moment I got home, I ordered a better diff and a self-centering shifter,” he recalled with a chuckle.

He’d scrounged and lost sleep and endured baseless barbs about parental support and whatnot. “Ever since I was a kid, I wanted to race wheel-to-wheel, but I didn’t have the budget. I finally got a taste for racing, and I knew then that was what I wanted to do, so I saved, busted my ass, and made it work.”