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1951 General Motors LeSabre

1951 General Motors LeSabre Engine: Second Prototype

Buick engineer Joe Turlay's challenge with the first prototype engine for the 1951 General Motors LeSabre was to make it extremely low. When engineer Charlie Chayne showed the early prototype V-8 to Harley Earl, Earl rejected it.

"This engine's too tall," he stated, noting that he intended to keep the LeSabre's cowl height to 36 inches. That meant that the engine itself couldn't be more than about 28 inches tall. "Impossible," said Chayne, but Turlay had a few tricks up his sleeve.

On his second prototype engine, Turlay put a windage tray in the oil pan, which allowed him to make the sump shallower. And he made the flywheel out of bronze. Bronze is more massive than iron, so the LeSabre's flywheel diameter ended up smaller than normal. Finally, he set the twin air cleaners beside rather than atop the V-8, all of which helped lower the engine's final height.

Hemispherical combustion chambers in the aluminum heads contained two valves per cylinder set at 90 degrees to each other. Pushrods rode on mechanical rather than hydraulic valve lifters, and activated an unusual rocker assembly. The intake rocker arms mounted across the heads on a single shaft in the normal manner. But pushrods for the exhaust valves passed between the cylinder bores, which meant the exhaust rockers ran lengthwise along the heads, riding on little individual minishafts.

Compression ratio at 10:1 was high for the time, and the 18.2-psi pressure boost of the supercharger put tremendous strain on the pistons during hard acceleration. The aluminum pistons themselves rode in wet, Ni-Resist iron sleeves. To assure rigidity, the block skirts extended down below the crankshaft centerline, and the main-bearing caps were crossbolted. Like the block, the radiator was also aluminum to prevent electrolytic corrosion inside the cooling passages.

Fully dressed, the engine weighed 550 pounds. This was relatively heavy, especially considering that the generator and a hydraulic pump were driven off the input shaft of the rear-mounted transaxle. The hydraulic pump powered the car's four built-in jacks, one at each corner. The jacks could be raised and lowered from the cockpit.

The car's top mechanism and hidden headlights were intended to be powered by this same hydraulic system, but instead they used individual electric motors. The LeSabre's electrical system was 12-volt, unusual for an American car at that time.

In the next section, learn how engineers addressed challenges in designing the LeSabre's transmission and suspension.

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