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1981 Cadillac Fleetwood V8-6-4: Three For in One


1982 Cadillac Fleetwood

1982 Cadillac Fleetwood

Cadillac has long been considered the top brand in American luxury. The beginning of the 80s was no different, but to maintain its position of leadership, Cadillac would take drastic measures. In a bold experiment that was as daring as it was unsuccessful, the company would use what must have seemed like technology from the future to solve its CAFÉ regulations problems of the present.Engine cylinder de-activation was not a completely new ideal, it had been done as early as the turn of the last century. For Cadillac it was hoped to be a quick fix to meet EPA fuel efficiency mandates. The drastic engine downsizing in 1980 did not produce the fuel savings hoped for. This time the new engine called the L62 would use a downsized 6-liter as its starting point. With added throttle-body fuel injection, the new V8 sounded like a good place to start a variable displacement platform.

V8-6-4 Emblem

V8-6-4 Emblem

The cylinder management was controlled by an on board “digital” computer. Called the MPG Sentinel, the computer was capable of executing 300,000 commands per second and was considerably faster than anything in most homes at the time. It would automatically deactivate cylinders based on engine speed, ERG position and intake manifold pressure. According to Cadillac, the transition would be seamless to drivers and was backed up with millions of hours of testing. They were so confident in the technology that it initially made the engine standard in all but the 1981 Seville. It would not be long before it became an option. By the 1982 model year the V8-6-4 engine had become an option and was stuck to standard limo duty. The 4.1-liter HT4100 V8 with its “Digital Fuel Injection” and the diesel were actually not much better in some respects. This was the start of the mass exodus to European cars, as the one two punch of variable displacement and wheezy replacements sealed the deal for many buyers.

1981 Fleetwood Brougham interior

1981 Fleetwood Brougham interior

The Fleetwood was Cadillac’s top big car and as such, it still embodied all the mystique of big American luxury. The long angular side profile was elegant looking thanks to chrome touches and the landau styled roof. Like many American luxury cars of the era, the interior looked as if a 18th Century French carriage was the inspiration for its styling. With living room grade seats and a long horizontally stacked dash, it features as much wood grain paneling as plastic. The Fleetwood was available as a coupe or sedan. The coupe was especially handsome with is Cabriolet style roof treatment. While up to eight color choices of leather were available for sedans, coupes used cloth for seat surfaces.

1982 Fleetwood Brougham coupe

1982 Fleetwood Brougham coupe

Not everything was old world. The Fleetwood with the V8-6-4 engine featured a digital dash with LED readouts for speed, mileage and other information. Electronic displays had been used in Cadillacs since the late 70s, often as options. For 1982 the digital displays were standard across the line and proudly proclaimed Cadillac’s arrival to the ’80s. There was no Touring Suspension option for the Fleetwood, but a Heavy-Duty Ride package was available with larger stabilizer bars and heavy-duty shocks.  When chosen without variable displacement, the Fleetwood was mostly trouble-free. Oddly enough, its been the Seville that has become the poster child for the 8-6-4 engine, as it must have been more appealing than the diesel V8 it replaced.

Standard digital display systems

Standard digital display systems

The rest of course is regrettable history. The V-8-6-4 engine would go down as one of Cadillac’s biggest mistakes (with the Cimarron following close behind). The modular displacement system made for a jerky ride and stalled often. A MPG display would come on in the dash, but noticeable drops in performance were the main indicator.  At full power the huge V8 made only 140 hp. Worse, at over 4,000 lbs. the engine struggled under certain conditions, making any MPG gains disappear. To the engine’s credit, it did have considerable torque, as Cadillac figured big luxury car buyers valued torque more than all out horsepower figures. Many dealers had figured out how to turn the variable displacement system off, making the V8 part of the engine just another GM big block. In this respect the engine was a solid trouble-free design.

In the end, Cadillac would concede failure. After 13 updates to the E-PROM chip, Cadillac would quietly move on to a yet smaller and more conventional 4.1-liter V8 for the 1982 model year. It would take Cadillac years t live down the debacle.  Reasons for the failed system were as broad as a faulty fuel injectors, crude computer technology and just plain old poor union made execution. A year later Mitsubishi had a similar system using an inline four-cylinder engine. It was far more successful technically, but the market ignored it mostly based on Cadillacs misfortunes.

Today successful variable engine displacement technologies have taken the sting out of owning a car with a big V8 engine.  Fuel economy in full-sized cars from Chrysler, Mercedes-Benz and even Cadillac can approach the efficiency of intermediates from 20 years ago, but with considerably more power. For Cadillac, the stigma of its variable engine debacle has long passed. That’s a good thing because the Cadillac we know today would say that modern quality control procedures insure that consumers will no longer be test subjects for new unproven ideals. We could take Cadillac’s word on that but I would not be willing to bet on driverless cars or levitation technologies just yet.

1982 Cadillac Fleetwood

1982 Cadillac Fleetwood

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One comment on “1981 Cadillac Fleetwood V8-6-4: Three For in One

  1. Pingback: Does Eco mode actually save more gas? - Page 2

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This entry was posted on September 22, 2013 by in 80's Cars, Cadillac and tagged , , , , , , , .
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