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In 1981, GM thought it had built a revolutionary engine in the V8-6-4, but it ended up becoming the company's worst for the decade.

The name Cadillac V8 may refer to any of a variety of V8 engines built by the Cadillac Division. The production of these engines started in 1914 when the Cadillac Division of General Motors released the first mass-produced engine.

The majority of Cadillac's V8 engines were good, but in 1981, Cadillac introduced a new engine that would be known for its complex electronics, the V8-6-4 (L62).

GM bet on something that was significantly ahead of its time. As a result, it was a complete catastrophe. The reason why it was a failure was that the technology wasn't refined enough for the job.

Cadillac made the V8-6-4 because gas prices were becoming expensive. So GM came up with cylinder-deactivation methods. The methods allowed V-8 engines to occasionally cruise on four cylinders and save a couple of miles per gallon.

All the Cadillac models in 1981 came with the V8-6-4. This infuriated the public even more because there was no other engine option. Critics stated that Cadillac's engineering team was thinking beyond technological limits without respecting those technological limits.

Let's find out what made the V8-6-4 a disaster and why the public hated it.

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The first time cylinder deactivation came to light was in 1905, with the Sturtevant 38/45hp. A more fuel-efficient cruise could stop three of its cylinders. In 1917, the Enger Twin-Unit Twelve used this method. This Cincinnati-built machine had an owner-operated cylinder cutout system, activated by a lever on the steering column.

General Motors didn't use the method until Cadillac tried it in 1981. The Cadillac L62 V8 was standard in every model it made for the 1981 model year except for the Cadillac Seville. The engineers at GM pulled in the Eaton Corporation, an electronics supplier, to help devise a way to shut down cylinders on demand.

They created a throttle body-dependent fuel management system meant to shut off two or four cylinders depending on load. This would help the V8-6-4 claim a 30% gain in fuel economy over prior powertrains.

The system accomplished this by combining a microprocessor with a series of sensors that monitored everything in the engine. It monitored the intake manifold pressure, engine speed, and coolant temperature.

When the system determined that the car was cruising and acceleration requirements were minimal, it activated a solenoid that mechanically locked the rocker arms, preventing the camshaft from operating valves in certain cylinders.

Any misfiring sensations that made their way into the passenger compartment were supposed to be cushioned by compressed air within the cylinders.

The Eaton-GM partnership had grossly underestimated the computational power required to keep up with the sensor readings spewing forth from the L62 when operated in the real world.

Whether the car was accelerating or decelerating, the rocker control system wasn't fast enough to react to the driver's right foot. This issue caused power production delays, making the engine unable to operate smoothly.

The fuel injection and deactivation systems had crossed wires to the point that neither understood what condition the motor was in. This meant that the throttle-body was either pouring too much or too little gasoline into the engine, depending on how many cylinders were really in operation.

At certain cruising speeds, the processor would get so worked up that it would hunt between cylinder counts, moving back and forth like an automatic transmission that couldn't quite find the right gear for the scenario.

The Cadillac V8-6-4 came with a gauge on the dashboard called the MPG Sentinel that would report on how many cylinders were currently pulling duty. The sentinel turned out to be useless since the near-constant reluctance and lurching involved with the deactivation process immediately alerted drivers to how many pots were firing.

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After introducing the infamous V8-6-4, GM was desperate to get out of the embarrassment. They introduced the HT4100 V8. The HT stood for "High Technology," and the displacement was 4100 CCs (cubic-centimeters) or 4.1 liters to use the more conventional measure.

Because it included a throttle-body fuel-injection system and a lightweight aluminum block with cast iron sleeves, the HT4100 V8 looked to be a game-changer.

From 1982 through 1987, it was part of the Cadillac range. It initially received positive feedback for its seamless running. But the engine was sluggish. The HT4100 V8 had 125 horsepower and 257 pound-feet of torque, making it about as powerful as a V6. Couple that with the weight of a Cadillac and you can see why it couldn't get out of its own way.

Furthermore, complaints plagued the HT4100 V8. It had troubles with the head gasket, coolant leaks, and oil pump failures. Replacement components were prohibitively costly, and most repair shops refused to touch them.

General Motors suffered another engine failure. This prompted GM enthusiasts to go for the 4.1-liter Buick V6 that was available in certain Cadillacs. It wasn't as sophisticated as the HT4100 V8, but it was significantly more dependable and trouble-free.

Marcus is a car enthusiast who loves writing about them. He travels frequently and always seeks out the best driving roads to really test a car's limits. His favorite cars are anything with a manual transmission, and he's been known to spend hours just shifting through all the gears.