ROAD TEST

CENTURY/BAE BMW 633 CSi TURBO

(Motor Trend, September 1982. Tony Swan. USA.)  

If you’re looking for a 633 CSi that’ll run with the other exotics, this is the only way to go.  

Sumptuous, yes. Seductive, jawohl, as few others. Civilized as Dom Perignon. Sure and silent as an assassins’s knife. But at this office the first question asked concerning a turbocar – any turbocar – is invariably. “whaddaya spose that rig will do?” So let us dispense with blood-red sunsets and secret valleys flashing past in the misty dawn to get right down to standing starts. What’ll this tricked-up supercruiser do? Well, it’ll just run heads-up with any XJ-S Jaguar in town, is all. Just dust Porsche 928s. Just frazzle Ferrari 308s. In fact, this car will show a tidy set of heels to anything in its class, and is even in the ballpark with somewhat smaller quickies like the everlasting Porsche 911 SC and Datsun 280 ZX Turbo. Heady company indded for a leather-lined luxo coupe that scales in at 3400 lb. “Golloy, officer, it didn’t feel like 110. Yes, I know it was only four blocks. Guess I just sort of got carried away.”

   The Century/BAE BMW 633 CSi Turbo is one of those rare cars that put Des Moines-to-Omaha luncheon runs into the realm of plausibility. We make the distinction between the plausible and the practical here, you understand, a distinction you would very likely have to flesh in with considerable detail before some local magistrate were you to actually attempt such a feat. But the point is that performance such as this has not been a conspicuous part of the 633’s character heretofore. Since its introduction (as the 3-liter 630) in 1976, this baron of Bimmers has been super in every sense but the one that counts most with hard-core enthusiasts: horsepower. A bump to 3.2 liters in 1978 had little impact on the car’s relative sluggishness, and ultimately it was left to our friends at Century BMW in Alhambra, California, to cue up more quick.

   Century is North America’s biggest BMW outlet, and promises to become even bigger with the recent development of its own in-house performance branch, Century Turbo Performance Center. Century Turbo operates in cooperation with BAE, the Torrance turbo specialists. BAE has developed turbo kits for every car BMW offers in North America (except for the 528e). The thing that makes the BAE effort noteworthy in this regard is that the various kits have all been emissions certified, which, off course, is the only way a factory-franchised dealer like Century could ever afford to get involved in such a project.

   The 633 installation is standard BAE fare, which is to say highly professional. The cosmetics are appealing and, more important, so are the results. The BAE kit employs a Garret AiResearch T04 turbo charger blowing through the 633’s Bosch L-Jetronic injection system at 6 psi max. This marriage has proven itself to be particularly well-suited to turbocharging in other applications, and so it is with BMW’s big six: smooth, quiet and potent. The system is beautifully tuned to minimize the low-end sluggishness that still plagues some turbocars, which makes plenty of sense since off-the-line torpor is one of the gripes against the stock 633. However, the system also delivers plenty of the high-end omigawd here-we-go rush that makes turbocars so much fun to drive. At its peak – achieved at 5500 rpm – the 633’s Century setup delivers 260 bhp, which is 80 more than stock.

   As the acceleration numbers indicate, this is enough to stir the blitzen Bimmer, 3-speed ZF automatic and all, along at a pretty respectable rate – a starling rate, in fact, at least to some of the other big-buck GT bravos we encountered out there in the streets.

   As you will perhaps have noted from the pictures, this BMW differs from standard in more ways than the $3500 worth of alterations that have been made under the hood. The car rides on fat Pirelli P7s mated to handsome 3-piece Epsilon modular wheels. And rides low, thanks to the substitution of shortened coil springs for the stock units, front and rear. The new springs have substantially higher rates than stock, and are matched to Bilstein gas dampers all around – strut inserts up front, height adjustable shock absorbers at the rear. The suspension package also includes heavier anti-roll bars front (28 mm) and rear (19 mm), both of them adjustable. It all ads up to a suspension setup that’s a good deal stiffer than stock, but not beyond the realm of civilized sports motoring. The Century 633’s suspension, with help from the P7s, did seem to have a capacity for transmitting lots of little lumps and bumps into the driver’s ears and fingertips, but no one on the staff seemed to consider this a real source of irritation. Rather, it figured as a worthwhile tradeoff for the new level of athletic prowess the big coupe displayed on Mulholland Drive and other similar stretches of choice twisties. Rolling in league with it fatter footprints (P225/50s versus P195/70s stock), the stiffened 633 truly thrived in the tricky world of decreasing radius and high-speed sweepers, with scarcely a trace of body roll. Although we were unfortunately unable to get the car on our skidpad, we feel certain the suspension modifications and P7s add up to much more than the standard 633’s .75 lateral g capacity. It is a surefooted setup that gives its driver the feeling he would have work very hard to get himself into trouble.

   The P7s didn’t have quite so salutary an effect on the 633’s braking performance. The stopping distances were certainly acceptable, and control good, but we would expect the P7’s excellent sticking qualities and the 633’s 4-wheel disc brakes to haul the car down from 60 mph in something less than 150 ft.

   About the only other modifications included in this package were inside the cockpit – an excellent Momo steering wheel with a Turbo logo horn button (important, right?) and a VDO boost gauge. Which brings us to the next performance question: What’ll she do at the cash register? And the answer, as you might have guessed, is still plenty. The base car, a 1981 model, stickered at $37,402. The turbo kit, installed, adds $3500 to this total, and the Century Turbo Performance Center will look after the setup for five years or 50,000 miles for an additional $895. Considering the vagaries of turbomotors, this service contract figures as a real bargain.

   Going for the suspension package, which was handled here by Suspension Techniques of Rosemead, California, adds another $1493, with the wheels ($344 each) and tires ($364 each) running the total up another $2832. While the various suspension elements may be separated from one another, we feel certain the improvement in handling wouldn’t be nearly as dramatic without the big P7s, and would opt for the whole package. In fact, the handling improvements wouldn’t be welcome even without the extra punch of the turbomotor.

   Add in the Momo wheel ($205.90) and the boost gauge ($125), and you have $9050.90 worth of additions for a $46,453 BMW 633 CSi. Even for senior Bimmer buyers, that’s a hefty premium – almost 20%. But if you’re looking for a 633 CSi that’ll run with the other exotic iron, it’s the only way to go.

Acceleration (sec)

  Top speed: 140 mph (est.)