To make much sense of the Lotus Turbo Esprit SE, you need to realize a few things. Lotus is, above all, a firm of enthusiasts. They're a resourceful gang of high-level tinkerers with a get-it-done attitude built into the company DNA by the late Colin Chapman. Despite ownership by GM since early 1986, there are no great cash reserves at Hethel, England, Lotus offices that can be applied like some engineering poultice to any technical flare-up that should develop. And the Lotus men like it that way. The logic runs like this: Don't ask any favors of GM, and GM won't ask any favors of Lotus. The result is a scrappy, comparatively lean organization that meets engineering challenges with ingenuity, not pounds of sterling. Just like a well-run race shop.

The cars these people build for the U.S. market, now two versions of the Esprit Turbo, mirror the company character in sharp detail. The Lotus view of what a 2-seat sports car should be is unique in the world, and can afford to be, with U.S. annual sales numbering in the hundreds, not thousands. By comparison, Porsche's annual sales seem positively huge. That's fine, though; it means 911s swarm the countryside like locusts, while a handful of Esprits garner Testarossa-class public attention wherever they go. The 911 Turbo and the new Carrera 4 fall in about the same price range as the SE, but both lack the Esprit's rakish appearance and exotic feel. They seem downright pedestrian by comparison.

Some features you expect to find in cars in the $70,000 price range are conspicuously absent in the new Lotus, however. You'd probably guess at first glance that the Esprit would have six or eight cylinders crouched under the rear deck. But surprise, surprise, the Lotus is powered by a turbocharged four. Or maybe, in this day and age, you'd figure on anti-lock brakes. Guess again. At first, these sound like painful omissions in a car this price. But talk to the men at Hethel, and you'll find that these anomalies, and a few others, aren't by default; they're the result of conscious engineering choices. The all-aluminum 16-valve four is short on cylinders but long on performance; it's right at the forefront of production-engine technology and has the highest output per liter (120 hp) of any mass-produced automotive engine in the world.

Okay, fine, but what about the brakes? It turns out Lotus has expended no small amount of effort getting just the right feel from the car's unboosted rack-and-pinion steering. But the steering doesn't get along well with anti-lock, at least in its current level of refinement. The strong brake pulsing of anti-lock on the verge of lockup sends a startling amount of kickback into the Esprit's steering wheel. In the engineers' estimation, either anti-lock needs to get smoother, or the car would have to be equipped with an elaborate power-steering system. Neither alternative seems feasible to Lotus at the moment.

The latest version of the Esprit Turbo, the SE (Special Edition) shows its heritage as soon as you lever yourself into the perfectly stitched leather interior. This is no focus-group car; the first impression is that this is a custom-built automobile assembled for a financially secure driving enthusiast of average height who travels with little luggage and who doesn't care much about rearward visibility. In fact, it is. It just so happens the owner profile fits quite nicely around most of the Lotus designers. A group of talented men designed this car, and their personalities are built into every glorious detail of the Esprit SE. A company didn't build this car, people did.

And these are people with the definite views on how to build a motor car. The SE is their best effort; in terms of performance and technology, it puts the regular Esprit Turbo on the trailer. And at $79,500, it also happens to cost an additional $12,000.

For 1989, the Esprit Turbo's powertrain has been reworked substantially. Not long ago we got our hands (and fifth wheel) on a U.S.-spec car, which, given the edition of the SE model, has to be considered the base car in the small car lineup. (Maybe calling two cars a lineup is stretching things bit, but, hey, we're in a charitable mood.) A new engine management system with knock sensing has been fitted, along with new fuel-injection and induction plumbing. There's a new turbo and exhaust system, as well. These changes bump up the base model's power to 228 hp, with torque peaking at 218 lb-ft. All this urge is fed through a new Renault-built gearbox with a slightly shorter 1st gear and fractionally taller remaining ratios. The result of these changes is a 0-60 time of just 5.21 sec. The quarter mile is dispatched in 13.99 sec, with a terminal speed of 100.2 mph. The chassis is unchanged from the previous car, which isn't a bad thing, since the car generates good objective handling numbers. On the skidpad, our car pulled 0.88 lateral g and jinked through the 600-ft slalom at an average speed of 63 mph. Stops from 60 consumed 130 ft.

While we were mulling those numbers over, we got word that Lotus was interested in having us visit England and show us something new. By sheer happy coincidence, we were interested in, looking. The something new was the then-secret SE.

In England, we discovered the Lotus people had taken their already seductive Esprit Turbo and gone to great lengths to make it even more formidable sports car. Serious in this context means prying still more power out of the hardest-working 2.2 liters in automotive production. The SE motor snorts out 264 hp at 6500 rpm, with the capability of 30-sec bursts of 280 hp. The regular steady-state peak torque figure has swollen to 261 lb-ft at 3900 rpm, while the redline has been bumped from 7000 to 7400 rpm. Meanwhile, EPA fuel mileage figures have barely budged; the SE logs 17 mpg city and 27 mpg highway.

Just how did those crafty Brits manage to whip still more power out of an already advanced machine? Glad you asked, seeing as how we just so happen to have all the pertinent details at our fingertips. The main change is the addition of an air-to-coolant induction-charge cooling system. Any other manufacturer would call it an intercooling system, but the Lotus people insist that the term chargecooling is more accurate. The Lotus chargecooling system is completely independent of the engine's regular cooling system, which operates at higher temperatures. As such, the chargecooling system has its own coolant pump, driven at half engine speed in the location where the distributor used to reside in the pre-1989 engines. The cast aluminum chargecooler housing sits atop the engine between the liquid-cooled turbocharger and the induction system.

During steady-state full throttle operation, it hauls induction temperatures down to the tune of roughly 170° F, resulting in an induction air temperature of around 140° F. When the engine isn't working so hard, and the chargecooling system is operating at less then full capacity, the induction temperature drops below this value, often around 70-85° F. Given full throttle, the engine is capable of turning that cooler, denser air into greater power. It is at these times when the SE motor is capable of short-duration dyno figures up to 280 hp. The power edge gradually drops off as the cooler, now working at capacity, lets the induction air temperature slowly rise until is stabilizes at the 140° F level where the engine makes its normal 264 hp. This means that, unless you've been running at wide open for about a half minute, the full 280 hp will be available at the drop of a foot.

Heated water from the chargecooler is pumped forward to a separate radiator mounted on the front of the cooling package tucked up into the nose of the car. In the engine bay, the chargecooler takes up little space. It can be comparatively small by virtue of its efficiency. By Lotus' figures, it's 3.7 times more efficient than an air-to-air induction cooling system of the same size. And the engineers reckon the overall efficiency of an air-to-air system looks even worse when you install it in a mid-engined car. Air-to-air intake coolers require a big supply of cool air to function. By the time you build sufficient scoops and ducting into the car's flanks to maintain that supply at all speeds, you've dirtied the car's overall aerodynamics that drag increases begin to cancel out the power gain.

With the drastically reduced induction temperatures provided by chargecooling, the engineers were free to pump more air into the engine, though most of the power gain comes from the cooler, denser air the engine breathes. Boost pressure has risen to what works out to 12.4 psi above normal atmospheric pressure when the engine is over 3000 rpm. A controlled amount of overboost is allowed before that engine speed to spike acceleration. Additionally, the boost pressure in the SE (and the regular Turbo also) is indexed relative to absolute zero, instead of being a set amount above the prevailing atmospheric conditions, as in some other turbo cars. This means that, while other turbos lose power as altitude increases, the Esprit SE's engine management system allows it to makes as much total manifold pressure as it does at sea level.

The new two-coil ignition system is triggered by the engine control module, with spark varied based on programmed timing and on coolant and induction air temperature. The engine is designed to run on unleaded premium, but if a lower grade of fuel is used, a block-mounted knock sensor will detect the onset of detonation and retard the spark timing the minimum amount necessary to stop the problem. If the detonation is severe and persistent, then boost pressure is reduced for a short time to ensure that the system doesn't cycle in and out of detonation. When the proper grade of fuel is used, all engine parameters return to normal.

A total of six injectors supply the engine with fuel. The four mounted in the intake ports run full time, while two more in the intake plenum nozzle only come into play under heavy load conditions. The electronic control module (manufactured by Delco Electronics but tailored for the Lotus) orchestrates all six injectors, some of which switch from firing every other engine revolution to every revolution based on demand. All quite sophisticated, don't you know.

In case you haven't guessed by now, an engine that makes up to 70 hp out of each little 525cc cylinder needs to be pretty robust. The Turbo SE definitely is. It has some upgrades from the regular Turbo Esprit engine to deal with the pounding. The piston crowns are chromed to give them better detonation resistance, and they slide in forged aluminum sleeves hardcoated with Nikasil. These aluminum sleeves shed heat more effectively than cast iron, and they weigh about a third as much. There are now dual oil coolers busily dumping genuine British Thermal Units overboard, and the liquid cooling capacity has been boosted 20%. Further down the line, the diaphragm spring in the clutch has been stiffened. Satisfied?

Now we wouldn't want to put this swell new motor in the same old chassis, would we? Of course not. The Lotus people made changes in numerous areas. First, they decided they weren't completely happy with the anti-dive geometry built into the front suspension, so they chucked it and realized an improvement in ride quality. The caster angle has been reduced significantly in the interest of lightening the steering at low speeds. Bump-steer geometry has been juggled and wheel travel increased. Stiffer springs are fitted up front, and gas-filled dampers are used at all four wheels. The wheels have gotten wider (an inch in front, a half inch in the rear), and the rears are now 16 in. in diameter. The fronts are the same 15 in. as before. The old 60-series Goodyear Eagle NCTs are now cushioning the side of a garbage barge on the Thames, and have been replaced on the SE with evil-looking 50-series Eagle ZRs at all for corners. The fronts have bulged up to 215s from 195s, and the rears are formidable 245s, up from 235s. These are not your garden-variety Eagle ZRs, but specially tuned skins created just for the SE.

Since the Esprit's fiberglass body was completely restyled for the '88 model year, it was a bit soon to do it all over again. Besides, it's beautiful. The changes to the SE are limited to a deeper front airdam and the addition of a rear wing like the one seen on the Commemorative Edition Esprit offered in 1988. According to Lotus, the car's minor aero changes have brought lift down close to zero at all speeds.

And what kinds of speeds might we be talking about? Well, we can't say for sure, since our time with the car took place almost entirely in a typical British drizzle. For now, we must rely on the claimed figures for the car, which, strangely enough, seem fairly trustworthy. We're encouraged by the fact that the 0-60 mph time we got on our garden-variety '89 Esprit turbo when we tested it in California (5.21 sec) was actually .01 sec quicker than what the Lotus people claim for the car. Therefore, when they say the Turbo SE makes the 0-60 trip in 4.7 sec, we're inclined to believe them. If indeed the SE runs that strongly, it's right in line with another Lotus-powered car you might have heard of, the Chevrolet Corvette ZR-1. The Lotus top-speed claim of 163 mph seems believable enough, as well. A quick dash around the two mile grounds at the Millbrook proving grounds had the car indicating better than that.

Aim the Lotus Esprit Turbo SE down a typical English country lane, dip heavily into the throttle in 2nd gear, and wonderful things start to happen. The boost clocks in at about 2000 rpm, and really begins to go to work by 2500. The power seems to build logarithmically until by 4000 rpm, you begin to wonder if maybe you should have selected a wider road for this little exercise. The rear wheels scrabble for traction on the damp pavement as the silky but insistent engine winds up to the 7400-rpm redline. The whine of the turbo is faint, but it somehow seems tied to your adrenaline level. Grab 3rd and you're ready to do it all again. The regular Esprit Turbo is a whole lot of fun, but the new SE runs so strong you just can't help but love it.

That's assuming you can make a few allowances before you strap into the SE. At almost every turn, the SE is a non-standard automobile-sometimes in wonderful ways, sometimes in weird ways. Just getting in is a practiced affair: The doors don't open wide and the openings are small. Once inside, you'll find the range of seat adjustment limited and that you can't recline the seatback without hitting the firewall. A 6-ft 2-in. driver fits, but just barely. Your knees and head are feeler-gauge distance from immovable (but padded) structural members. You can pump up the lumbar support to taste, but that's the only comfort adjustment available. The steering wheel stays right where it is for the life of the car. You adjust to the Lotus, not the other way around.

With unboosted steering, a heavy clutch, and a stiff shifter, the SE's overall control effort is high, but it's balanced, and that counts for a lot. If this were an airplane, we'd say the Esprit had excellent control harmony. Everything you touch has a solid, mechanical feel. Make the mental adjustments (most people can) and the Esprit feels just right. A short test drive might not be enough, but a couple of days does the trick.

The best thing about the chassis is the direct, nicely weighed steering. Low-speed maneuvering is considerably easier with the new front-end geometry, but the car still feels stable at all speeds. With this much power on call, it's easy to hang the tail out, but like virtually every turbo car in the world, precise throttle modulation is critical to keeping the chassis in balance. Making the rising boost curve match, but not exceed, the available traction is an endlessly fascinating exercise that should keep SE owners occupied for many happy miles. The lively, communicative steering makes the job of salvaging those occasional bad situations something to look forward to. Still more help comes in the form of the grippier, quicker-responding Eagle ZRs. On a per-dollar basis, the Lotus Esprit Turbo SE is not the most capable sports car you can buy. It's solidly in the running, however, for being the most enjoyable.

Sunk like a pea in a pod in the beautiful leather interior with a wide-screen view of the world rushing by the windows, only the most resolute whiner could fail to be caught up in the Turbo SE's enthusiasm. Most serious drivers would swear they've had their pleasure and amusement centers wired directly into a control panel in Hethel. There, a group of serious-looking white-coated engineers are proceeding to bang every button in sight.

Motor Trend
Vol. 41, No. 7
pp. 64-70
July 1989

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