Oldsmobile’s W-43 V-8 Engine Was a “Killer” 32-Valve Prototype

One of the most notable participants in the 2024 Detroit Autorama is a special Oldsmobile 4-4-2 build packing a rare, experimental V-8 engine. To read about the twin brothers from Detroit responsible for this “Killer” project, click here. What follows is a technical and historical overview of the so-called W-43 prototype.

The mythical Dr. Olds was GM’s self-appointed innovation guru, with mass production, speedometers, front-wheel drive, turbocharging, a diesel V-8, automatic transmissions, anti-lock brakes, and chrome plating to his credit. So it should be no surprise that Olds engineers were pioneers in the movement to cram additional valves into their combustion chambers in pursuit of extra power. Behold, the W-43 prototype engine.

Oldsmobile’s special performance packages were generally coded with the letter W. In the late 1960s, the cause was volumetric efficiency: pumping extra fuel and air into—and exhaust out of—the engine to boost torque and horsepower. Work on the prototype W-43 V-8 shown here—a 455-cubic-inch muscle motor topped with heads sporting four valves per cylinder—began in earnest in the fall of 1967, though some of its technology had been in the engine lab for years.

One-upmanship was clearly at play in the W-43’s genesis. In the mid-1960s, Chrysler’s second-gen Hemi was the scourge of street and oval-track competition. Olds strived to trump Mopar by venturing beyond the Hemi V-8’s two valves per cylinder.

For the four-valve W-43 experiment, of which at least two examples are said to remain, a single chain-driven cam between the cylinder banks activates 16 pushrods. Each rod opens one pair of valves via rocker arms. To optimize this geometry, and to trim the mass of the pushrods in pursuit of super-high-rpm capability, the camshaft is elevated in the block exactly one inch in comparison with the 455 donor V-8.

Instead of Chrysler’s spherical combustion chambers, Oldsmobile used a simpler pent-roof arrangement which tipped valve faces toward the bore’s centerline. Spark plugs are centered to minimize flame travel, a configuration that necessitated sealing tubes in the valve covers. Pistons are domed.

To expedite the development of these new cylinder heads, Olds engineers employed a flow bench that could accurately assess temporary mahogany models. Best results were achieved with 1.75-inch intakes and 1.375-inch exhausts. This yielded a 43 percent increase in valve curtain area—likely the reason that figure was selected for this engine’s code name (curtain area = valve circumference x lift).

The 455-cubic-inch block, which continued 4.125-inch bore and 4.25-inch stroke dimensions, included one notable upgrade: To assure durability, new four-bolt main bearing caps were machined from forged steel.

Test results reported by Hot Rod magazine indicated a peak output of 440 horsepower at 4600 rpm with mild valve timing and a 4×2-barrel induction system. Those figures are modest by today’s standards likely because the engine was measured early in the development process.

The late 1960s were Motown’s horsepower heyday. The Hurst/Olds specials introduced in 1968 are now highly prized collectibles. Olds engineers also built hot marine powerplants and twin-turbo V-8s intended for Can-Am racing. A spinoff design was coded OW-43. Experimental dual-overhead-cam, 32-valve V-8s were also constructed for dyno testing.

Unfortunately, doomsday lurked around the bend. In the early 1970s, the feds tightened emissions standards and OPEC triggered an energy crisis with an oil embargo. Exactly what Olds didn’t need was a V-8 which was heavier, bulkier, more expensive to manufacture, and thirstier than conventional designs.

Thus, the W-43 was shelved and never reached production status.

It wasn’t all wasted effort, however, as this fantastic footnote demonstrates: Oldsmobile’s 2.3-liter Quad-Four—produced from 1987 through 2002 and used to power millions of Chevys, Oldsmobiles, Pontiacs, and Buicks—furthered W-43 lessons from the ’60s with the addition of dual overhead cams. The Quad-Four was America’s first four-valve engine as well as the final powerplant wholly developed and manufactured by Oldsmobile.

That legacy also includes an entry in the speed records books. An Olds Aerotech streamliner, powered by a turbocharged Quad Four and driven by A.J. Foyt, topped 267 mph in an epic 1987 measured-mile run at the Fort Stockton Test Center in Texas, seizing the world land-speed record from Mercedes-Benz.

***

Check out the Hagerty Media homepage so you don’t miss a single story, or better yet, bookmark it. To get our best stories delivered right to your inbox, subscribe to our newsletters.