Full Test: 2006 Lotus Exige by Secant Vehicles

The last time we saw an American entrepreneur stuffing a powerful American-built engine into an unsuspecting British sports car, it was the 1960s and it was Carroll Shelby. The meek AC Ace roadster was, shall we say, invigorated by his fitment of the Ford V8 into its lightweight body shell.

Fast-forward nearly a half-century. Secant Vehicles, a small start-up headquartered in San Francisco, has developed a GM Ecotec engine conversion for every Lotus Elise (or Exige) built since the waspish midengine sports car's 2005 introduction.

The players are different, but the three-step formula for the Lotus Exige by Secant is the same as Shelby's:

Step 1 — Find a small car.
Step 2 — Add power.
Step 3 — Kick ass.

So has history been repeated? We drove Secant's development car, a 2006 Lotus Exige equipped with the optional Track Pack suspension, to find out.

Powered by the General
The powertrain of choice for the Lotus Exige by Secant isn't a pushrod V8 like Shelby's, but instead an intercooled and supercharged, 2.0-liter Ecotec inline-4 that you find in the Chevrolet Cobalt SS Supercharged.

This GM-designed mill has been worked over by the capable folks at Katech Engineering with a forged crank and rods, sodium-cooled valves and a smaller supercharger pulley for increased boost. Output in the Type 1 conversion is a claimed 280 horsepower at 6,600 rpm and 241 pound-feet of torque at 4,500 rpm. Secant's future Ecotec engine packages promise even higher performance.

On paper, this power increase gives the Exige the bite of a true predator. That the powertrain conversion adds just 4 pounds to the rear of the car is important in a car as sensitive to weight distribution as the midengine Lotus. The conversion's complexity rules out a do-it-yourself kit, so Secant builds all cars to order at its facility in Detroit.

This car has been equipped with Secant's Type 1 engine swap ($19,900), larger front Brembo brakes ($2,695), bigger wheels and tires ($2,840), a $2,300 bundle-of-snakes tubular header, a $590 baffled oil pan, plus assorted non-essentials until the total comes to $29,295.

Of course this figure is in addition to the cost of the Lotus that you start with. Once you add up everything, we figure that a brand-new 2008 Lotus Exige by Secant would represent $91,220.

Fuel-Hardy
Upon delivery of Secant's development car to our door, we were told that the car's tank had been filled with 100-octane fuel. This immediately sent up red flags with us, and we wondered whether this car might be a specially tuned ringer or whether it might self-destruct on pump fuel.

Secant explained to us that it has done a kind of makeover of the electronics here, and it has defeated the stock Lotus traction control entirely and commandeered the stability control button to perform map switching for different fuel-octane ratings.

When you start the Secant-tune Ecotec, the engine control unit defaults to a pump gas-friendly calibration. Pressing and holding the button while parked activates a more aggressive programming map intended specifically for unleaded racing fuel of 100 octane or better.

It's a pretty clever hack, although some people might miss the stability control, as the Lotus-calibrated system is one of the few that actually works as a high-performance driving aid.

Rolling in My Two-Point-Oh
All of the Secant's major mechanical interfaces for the new engine — the throttle, brake and transmission — are well-integrated. Clutch take-up is smooth and progressive, and there are no hiccups or flat spots in the power delivery even when you're grinding through traffic. The re-engineered shift linkage moves more positively than the stock Lotus gearchange. Even the air-conditioning works.

Then we hit our testing site. During the second acceleration run, the dipstick of the Secant engine blew out of the block, dousing the engine bay with oil. A quick call to Secant confirmed that this is a known issue with supercharged Ecotecs. We wiped up the mess the best we could, zip-tied the dipstick securely into place and crossed our fingers.

The car then clicked off repeatable runs to 60 mph in the low 4-second range. The best run was 4.0 seconds (3.8 seconds with 1 foot of rollout like on a drag strip) on the "race gas" calibration. The quarter-mile flashed by in 12.5 seconds at 107.7 mph, making the Secant Exige substantially quicker than a normally aspirated Elise. The Secant is only a little less so when compared to the last 220-hp Exige S we tested, which did the quarter-mile in 12.8 seconds at 105.5 mph (partly because it weighed 117 fewer pounds than the Secant's 2,169-pound test weight).

Rolling Stock Needs a Rethink
Secant reckons that the wheel and tire package on our test car is the largest that can be stuffed under the Exige's fenders. They sure look the business. Satin-black Team Dynamics wheels and wide, sticky Toyo R888 R-compound tires are like steamroller drums under the petite body of the Lotus.

In braking, the Secant came to a halt from 60 mph in 103 feet. Some of this eye-popping stopping power is owed to the track-ready tires, yet the Secant's brake package is outstanding in any case. Initial bite and the subsequent modulation is predictable, the pedal action remains firm and fade is a non-issue, making these binders among the most confidence-inspiring we've encountered.

There is such a thing as too much rubber, though. The Secant's 225/45R17 front tires rubbed noisily on parts unseen as we cranked the steering wheel near the stops at full lock, and the monstrous 255/35R18 rear meats deposited molten tire sludge due to contact with the lips of the fenders.

Furthermore, the large (almost comically so) rolling diameter of the front tires — combined with the required wheel backspacing to fit them — distorts the sublimely effective suspension geometry of the Lotus. As a result, pavement irregularities make the Secant nervous, and the steering effort grows exponentially heavier as you wind on lock. You have to muscle the Secant around tight bends with your shoulders, clenching the wheel to prevent its escape from your grasp as it kicks like a pissed-off Percheron with each bump the front tires encounter.

Stay on top of your steering inputs and the Secant rewards you with a handling balance in the corners that's easy to adjust. Give the throttle a quick lift and then settle into the pedal again and the grippy rear tires come into play progressively. The sticky tires afford the Lotus huge traction, and the car catapults away from apexes with devastating effectiveness. It's just a shame that extracting the Secant's performance requires a blemish-free surface like a racetrack, prone as it is to nasty bump steer.

Our testing surface has minor irregularities that most cars sail over unperturbed, but not the Secant. As a result, its 70.9-mph speed in the slalom trails the 74.0-mph effort by the Exige S. And its 0.97g result on the skid pad just pips the 0.96g performance by the Exige S.

The Loud Pedal
At 101 dBA at full whack, the Secant is among the loudest cars we've ever tested. The open-element intake, literally inches from the driver's head, is like a megaphone through which a piercing supercharger whine joins in riotous accompaniment with the hissing intake and snorting exhaust.

It's entertaining at first, but with so little Lotus separating the racket from your skull, the din quickly grows tiresome. The Secant's soundtrack will only be appreciated by those who find death metal melodious.

Fortunately, where there's sound, there's fury. You can put your foot down at low revs and get a meaningful and linear shove from the torquey engine, and the sensation is one of supreme tractability.

To quantify how much of the Secant's urge is attributable to the race gas, we visited Harman Motive's Mustang dyno in Torrance, California. Here we conducted several pulls with each fuel calibration and found that the difference between the two maps is minimal — switching between them netted a maximum difference of just 5 hp.



We figure that the peak power we measured at the wheels of 210 hp (race gas map) equates to roughly 260 hp at the flywheel. Looking closely at the dyno result, the power peak arrived right at the 6,350 rpm fuel cut-off, which is 650 rpm shy of where the redline is supposed to be. Had our test car pulled all the way to the 7,000 rpm rev limit, it would have come close to achieving the 280 hp that Secant quotes.

Octane will also play a role in the final result. Once we topped the tank with premium unleaded, it became clear that the pump gas calibration that Secant developed using the 93-octane fuel available in the Midwest is far too aggressive for use with our 91-octane fuel in California. As a result, the engine detonated severely. Secant reports that it's still working on a 91-octane calibration and that customer cars won't experience this issue.

But we didn't have a customer car. We were driving the only one we had, and this one did not like our local premium fuel. The only solution was to mix in a few gallons of race gas to bring the octane above 93. For a street car, this is a deal-breaker.

In the Final Analysis
Secant's Ecotec-powered Lotus Exige delivers the performance it promises, but only under the right circumstances. On smooth sweepers of sufficient radius where the steering angles of the tires remain in their happy place — and with warm tires and cool air and the right fuel in the tank — the Secant Exige is a phenomenally rapid point-and-squirt device. The Ecotec engine's immediate, tractable punch can be exploited to its fullest potential by the chassis without resulting in fruitless wheelspin, and you can place the front tires within millimeters of where you want them with a simple act of will.

We experienced several hiccups with Secant's development car that the company says will be ironed out in production. Still, we can't help but think that the economics of the conversion are not in Secant's favor, as the 240-hp Lotus Exige S240 offers performance that renders the Ecotec conversion an expensive redundancy.

The Type 1 conversion makes more sense to an owner of a normally aspirated Elise that is getting on in miles and could use a refresh. It will help if this owner is already hard of hearing. And wealthy.

We wish Secant the best. Taking on a fully engineered powertrain swap that meets modern expectations of drivability, durability, convenience and performance is no small undertaking. Mr. Shelby had it easy by comparison.

The manufacturer provided Edmunds this vehicle for the purposes of evaluation.