Early on, NASA Arizona member Sean Shepard found the recipe that suited him best. “I like lightweight cars,” he said.
Simple, lithe, moderately powered (at best), and kind to consumables — these traits provide the sort of sensations and challenges that kept him satisfied with pushing his cars as hard as possible.
Shepard first fell in love with an S2000, then a Spec Miata. He had gotten acquainted with the popular front-midship platform from Honda and took it to Time Trial 3 and TT4. Along the way, Shepard found the challenge of wheel-to-wheel racing too tempting to pass up, and so he tried his hand at Spec Miata. When the damage bill got to be too much, Shepard decided there had to be an alternative.
The exacting nature of wheel-to-wheel and the intensity of a super-svelte, stripped racer were the two immediate aims he had in his replacement, but he also hoped for an edgier, more focused machine if one existed.
There aren’t many road-legal production cars that can hold a candle to the Lotus Exige when it comes to directness. In comparison to the S2000 it replaced, Shepard’s Exige felt almost formula-car-ish. When daily drivability and creature comforts are not a concern, it can afford to be that much tauter than the admittedly focused, yet comparatively compromised S2000.
“The joke among friends is that it’s a skunkworks project. The Exiges are not comfortable — more like hastily assembled toys with more in common with an experimental airplane than a street car,” Shepard said.
He stumbled across a particular example that caught his eye. Being coated in highlighter yellow paint helped in doing that, as did its reasonable asking price. The car had been transformed into a racecar in 2009, then subsequently crashed and repaired. The presence of some primo parts in this nicely-priced package helped him look past its history.
There are plenty of clear indications this machine is barely a production car. Along with its flat floor — few cars in its price range include factory aero items that provide a BTM advantage in TT4 and TT5 — the Exige’s alignment is set with shims, so once you’ve set it, it’s basically fixed.
Along with a 2ZZ motor making 270 horsepower, the chassis had been mostly sorted. A cage from a Lotus Cup car, a homemade splitter, a dual-element Pilbeam wing, Nitron coilovers, as well as a setup that suited it to Hoosiers — Shepard’s tire of choice. “I believe that the A7s are the only tires you can run with this car since its low weight makes it challenging to heat them.”
The car was from the NASA Utah region, and he brought a fresh set of A7s along with him to meet the owner at Utah Motorsports Campus to test drive the car on Friday, and on Saturday he won TT2 in a field of 10 cars. The funny thing is, he was nowhere near mastering the car at that point.
“It’s fair to say the car was driving me that weekend. (Compared with) the Spec Miata, which is a relatively chill experience, the Exige was sensory overload,” he said. “If you take a closed-wheel driver and put them in a shifter kart, there’s a bit of that same shock, though probably not as much. It truly felt like I was going from a car to a go-kart.”
The braking was what struck him most. “It’s a function of the weight, but it stops incredibly well. The first time I drove the car, I was using the CCW configuration, and I attacked Turn 1, braked, and realized I had to get back to throttle to get to the turn-in point. I just wasn’t familiar with anything that could stop like that.
“I even out-braked Tage Evanson’s ST1 Civic pretty consistently,” he added. “I’d leave my braking points past some of the normal markers in certain corners. Evanson came up to my stall afterward and asked, ‘How the hell do you pull that off?’”
An encouraging first outing in anyone’s books. However, the car was far from ideal in terms of setup and its place in the new NASA ecosystem.
Blower Woes
The supercharged 2.0-liter Toyota lump behind the cabin was not short on power, but peakiness kept it from feeling as fast as 270 horsepower in a 1,950-pound package would suggest. “I realized that peakiness kept it from being classed well under the NASA ruleset,” Shepard admitted.
Like engine performance, the engine’s heat capacity was limited by the way the force-fed motor is shoehorned into a compact space. “The Exige has three big intakes in the rear — one on the roof and two behind the cabin, but the intercooler is mounted on top of the motor, and it just doesn’t get enough air. By the end of most races, it was heat soaking pretty badly.”
The final flaw was its gearing. Despite second and third gear capturing the full force of the motor, as soon as Shepard shifted to fourth at 103 miles an hour, the motor fell flat on its face. Those few flaws sowed the seed for a future swap.
After a year and a half of competing, the 2ZZ developed a rod knock and Shepard could see the time for a swap was upon him. He had his eye on the popular Honda K24, a motor that Honda sold in numerous models for the American market. With another .4 liters over the 2ZZ it replaced, the K engine would be far more flexible.
Leave No Stone Unturned
He hired Bay Area outfit TrackSpec Autosports to swap the engine and perform a full rewire, along with a PDM, AiM dash, and Haltech ECU to make the most of the platform and a new motor.
The new engine didn’t last long due to a cylinder sleeve issue, so they bought a stock K24 and the six-speed from a Civic Si from a JDM dealer.
“We removed all the externals, added the more efficient RBC intake from a 2006-2011 Civic Si, a J37 70mm throttle body, and a DTR K24 Lotus header. We had to change the oil pump to a ported pump since the standard oil pump doesn’t prevent cavitation over 8,000 rpm. We’re not currently revving that high, but we’re planning to soon,” he added.
The stock engine made 224 horsepower at the peak of the curve, but the father-son duo had to detune the output to 206 horsepower to suit the classing weight of 2,067 pounds, which took about 150 pounds of ballast to achieve. “I advise anyone considering a K-swap to start with a stock/near-stock motor — it’s much easier that way,” Shepard said.
Not having any supercharger ancillaries to weigh it down, the K24 takes up less space than the 2ZZ and cuts roughly 50 pounds. Additionally, the full rewire saved another 50 pounds. “They got rid of almost all the wiring — now there’s just the ABS wiring left.”
On the subject of brakes, the Exige came with either Cup brakes at the front and regular brakes at the rear, and Shepard swapped back to the regular brakes for a couple of reasons. “First, I wanted to fit 15-inch wheels. Second, the ABS system struggled with the Cup brakes. The problem with the Cup brakes was that the fronts were huge while the rears were stock, and I hadn’t been able to change the proportioning. I think that was overwhelming the stock ABS. I’d say the ABS is serviceable, though you can definitely overpower it and it ices out,” he said.
Thankfully, the running costs of the Exige aren’t high. “It’s not the cheapest car in the world to buy — there’s a Lotus tax on most of the parts, but I run 225 and 245-section tires, so consumable costs are basically as bad as a Miata’s. I swear by the G-LOC R10 up front and R12 in the rear, and I’ve put seven days on them so far without any problems. I’ve put 10 days on the Hoosiers before seeing real dropoff, too.”
The Perks and Penalties of Being a Misfit
The car is super fast, but it is not without its shortcomings. “It’s an overdog ST3/TT3 car, but I have to drive it super hard — to corner faster than you believe your body can take,” he said. “If you look at my midcorner speeds in high-speed corners, I’ve got 10-20 mph on some of the fastest ST1/ST2 cars around here.”
Given that Shepard is willing to drive consecutive qualifying laps during a race, it’s easily one of the fastest cars in the field — but that lap time is contingent on its remarkable braking and cornering performance. Straightline speed plays a role in race performance, and its power handicap becomes a real hindrance in ST racing.
“I think it’s the quickest out there, but I lose multiple positions off the start every time,” Shepard said. “I mean, I’ll get walked down the straights by ST5 cars. Even a Spec E46 had to brake on the straight to let me by.”
At Arizona’s Podium Club, there are a couple of notable differences between a car with more weight and power. Compared to Kennel’s TT1 lap-record-setting Corvette, which has more tire on the front than Shepard has on the rear of his Lotus, “We’re seeing a minspeed difference of 9 mph (101 mph in the Exige vs 92 mph) in the TT1 Corvette,” Shepard admits.
VIDEO
Sean Shepard wheels his K24-swapped Lotus Exige around Podium Club at Attesa.
If and when he is able to challenge another car for a corner, he is not concerned about a mid-corner slide screwing his chances. “The Exige has so much grip in the corners that it feels pretty safe. Unlike going two-wide in Spec Miatas, which feel like they’re teetering on the edge of grip, I can readjust the Exige midcorner if there’s an issue.”
It’s fairly forgiving, then. “With my lap times, some people think I’m a superstar, but it’s actually easy,” he said. “I’d say the car is set up to be really soft, and that made it understeer just a bit, but after we installed a rear bar, we cured that. I prefer softer cars. I like the body to move around. It gives a lot of feedback. The information through the wheel is detailed, too, since it doesn’t have an electric steering rack.
“It has a lot of aero, runs really good tires, has a good limited-slip diff, and has a great setup — these make a huge difference in drivability,” he added. “Without them, I’ve heard these cars aren’t so forgiving.”
Even so, there are limits to what a midengine car on sticky slicks will let its driver get away with. “It’ll still spin like a top if you get too sideways, not just because of the short wheelbase, but because the rear wing will stall,” he said. “For that reason, I try not to push to the point where I need to make a lot of corrections at corner entry. I just drive straight into the corner and leave the braking as late as possible; trying not to trail much.”
Being a factory Honda item, the K24 has been rock-solid in the past year of driving. Even with its cornering forces, oil starvation isn’t an issue. “If we fill the oil up completely, the Accusump never triggers (even with sustained 1.8 g), but if we have it at the midpoint, we get only very short triggerings of the Accusump.”
“What I value most is an analog driving experience. I don’t know if there’s anything that can offer more of that, aside from a Radical, but then I wouldn’t have people to drive against,” he said.
“The Exige is analogous to an S2000 – just a better-in-every-way S2000. Like the S2000, the challenge with running the Exige in TT is getting enough front aero. We’ve gone with a pretty big time-attack-style 8-inch splitter, just 1.5 inches off the ground,” he added. “It’s so low I have a hard time getting it on the scales for compliance. It scrapes under braking, but that and the flat floor (from the factory) really help with the high-speed balance. It’s just so planted.
“Now, I honestly have no desire to buy another car,” Shepard said. “It’s fast, involving, and it’s been totally reliable. Even though there aren’t many super strong parts used, I’ve never had to replace anything from failure yet.
“Maybe I’ll install paddle shifters and a turbo one day, but then I won’t be able to class it,” he said. “But, really, I can’t see myself in another platform,” he concluded.
And for good reason. The Exige, because of its classability, its involvement, and its visceral nature, makes it the “it” car Shepard has always dreamed of. In light of that rare combination of qualities, why would he change?
Sounds like he’s got it all figured out.
