Cover Story: Annual Design Awards
CADDY'S 295-HP SMOOTHIE
When Cadillac's Seville Touring Sedan hit the road last year, the critics raved. Finally, an American luxury car that could compete with the Europeans and the Japanese. The only problem was, it had a wimpy engine that ran out of steam at highway speeds. But this fall, Cadillac responded to the imports' challenge, and it has come up with a winner: The Northstar engine, a 4.6-liter, aluminum, 32-valve V-8, delivers 290 foot-pounds of torque and 295 horsepower. The engine is paired with the smooth-shifting electronic Northstar transmission and provides Cadillac's first completely new power train in more than a decade.
For the 1993 model year, the system was added to the STS and Eldorado Touring Coupe, and a retuned version of the engine, with a maximum 270 horsepower, is available on the Eldorado Sport Coupe. Now, sales of those Northstar-equipped models are outstripping supply. Models with the old 200-horsepower engine are languishing in showrooms, even though they list for thousands less than the Northstar-equipped versions.
The quiet, smooth-running Northstar system is a good match for the sleek STS and stylish Eldorado. Even at 70 mph, a tap on the accelerator delivers a surge of power that allows a quick move into the passing lane, delivering a race-car zip that today's luxury-car buyers are accustomed to. A two-piece engine block, usually found only in racing engines or exotic sports cars, provides greater rigidity and quieter running.
Cadillac engineers knew that the Northstar had to match --or beat--the world's best engines. So they tore apart and studied everything from Honda four-bangers to a BMW V-12. Once design work had begun, computer simulations helped reduce the trial and error that is typically needed to fashion parts that are lightweight yet strong.
The engineers also applied design-for-manufacturability techniques to reduce the number of parts: Northstar has just 1,200, vs. 1,700 in a Lexus V-8. That simpler design helps reduce the manufacturing time per engine by nearly 60%.
The other components of the Northstar "system" are Cadillac's new 4T80-E electronically controlled transmission and road-sensing suspension. With Northstar's increased power, Cadillac engineers wanted to balance the power train with a new suspension to maintain taut, stable handling without a harsh ride.
The road-sensing suspension they came up with--which is standard on all Northstar-equipped cars--is computer-controlled to improve ride comfort and cornering. The suspension has sensors that "read" the road, adjusting shock absorbers and struts in milliseconds when the car hits a bump or rut. It's fast, too: Even at 60 mph, there's a reading once every inch of road for each wheel.
Finally, Cadillac wanted owners of Northstar to be proud enough to pop the hood and show off the engine. So they asked the design staff at General Motors to spiff up its appearance. The group added a sleek, fluted cover on top of the engine, with "Northstar" emblazoned across the side. And the designers routed spark-plug wires neatly along a recessed channel in the ribbed valve covers. Best of all, owners who want to ignore the engine certainly can: According to Cadillac, this power plant won't need a tune-up for 100,000 miles.Kathleen Kerwin and David Woodruff in Detroit