1951 General Motors LeSabre Engine: First Prototype
On the 1951 General Motors LeSabre engineering side, Charlie Chayne let his imagination run just as wild as Harley Earl's and designer Edward Glowacke's, and everything Chayne thought of he incorporated in both XPs.
Mechanically, the two cars turned out to be similar but not identical. The XP-9 (later called the Buick XP-300) was more complex than the XP-8 and, for that reason, wasn't nearly so drivable. For example, The XP-9's hydraulic system powered so many accessories -- seats, windows, door detents, cowl vents, etc. -- that it had a lot more places to spring leaks. Even though the XP-8 was fairly complex too, it simply had fewer hoses and hydraulic connections.
A 215-cid aluminum V-8 with square bore and stroke dimensions was designed to power the LeSabre. It has a Roots-type, three-lobe, Detroit Diesel supercharger, and the engine used to be set up to run on both gasoline and methanol. (It's currently fueled only by gasoline.) On methanol, gross-rated horsepower topped out at 335 at 5200 rpm, with torque at 381 pound-feet at 3650 rpm.
These were mind-boggling power outputs for 1951. Previously, the highest horsepower ever advertised in an American production passenger car was the Duesenberg SJ at 320 bhp. Even the early Cadillac V-16, with more than twice the displacement of the LeSabre V-8, put out a mere 185 bhp in its best years.
For a 215-cube V-8 to deliver 335 horses -- more than 1.5 horsepower per cubic inch -- seemed stratospheric at the time.
The LeSabre has two twin-barrel Bendix-Eclipse carburetors, each fed from a separate fuel tank. One carburetor and one tank are for gasoline; the other tank contained methanol and supplied the second carburetor.
The two 20-gallon aluminum tanks are situated in the rear-fender area and are accessible through filler doors in the tailfins. To open those doors, you push on the words "Gasoline" or "Alcohol" embossed into them. Each filler cap is integral with the door. The right-hand tank is for methanol ("alcohol"), the left for gasoline.
When used, the methanol tank needed a special funnel to keep liquid from spilling onto the finish because methanol destroys paint. The funnel, which still exists, has a pet-cock and an overflow tube that routes any spillage down to the ground under the car.
In Earl's day, the supercharged LeSabre engine normally ran on the gasoline carburetor only. When the driver punched the accelerator pedal, the methanol carb kicked in via a progressive throttle linkage and, at the same time, a valve in the fuel line from the methanol tank opened up. At that point, the 3800-pound LeSabre was pretty much ready to go into orbit.
The unusually low intake manifold, designed by Buick engineer Joseph Turlay, doubled as the block's valley cover and also suspended the camshaft from its underside.
The cam did not reside in the block as in most pushrod engines. Instead, it hung down from the bottom surface of the intake manifold and was chain driven. The supercharger, driven by triple vee belts, fit neatly into the engine valley.
But Harley Earl would reject this early prototype. Continue to the next section for the complete story.
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