Cadillac V-16 Imperial Convertible Sedan

On January 4, 1930, New Yorkers were treated to an engineering tour de force. At the opening of the National Automobile Show at the Grand Central Palace, Cadillac unveiled the world’s first production V16 automobile engine. The late historian Griffith Borgeson explained it elegantly: “It really made history and it made Cadillac, beyond all discussion, the absolute world leader in motoring magnificence…It was the super engine that set the whole exercise apart.” The creative genius behind this powerplant was Owen Nacker.

Born in 1883 in Highland, Michigan, Nacker had been a consultant to Alanson Brush, maker of the 1907-1911 light car that bore his name. He was recruited for Cadillac by Lawrence Fisher (the activist sibling of the seven Fisher brothers who founded Fisher Body Company) from Marmon. Howard Marmon had been hatching a V16 since the latter days of 1926, and Nacker had worked on the project, some say as a consultant. By March 1927, a V8 for the new LaSalle, Cadillac’s lower-priced companion car, was reality, designed by Nacker. Certainly shortly thereafter, he was working on Cadillac’s V16.

Nacker flouted a great deal of Cadillac tradition. The new engine was designed with overhead valves, which the division had never used. Overhead valves were noisy, but Nacker adopted a new setup developed by GM engineering that effectively provided zero-lash operation, using oil pressure to rotate each rocker arm around an eccentric shaft, taking up slack while backing off as the engine warmed up. Moving the valves to the heads relaxed the constraint that manifolds had to compete for space in the valley between the cylinder banks. Manifolds could now move to the outside. This was also important because the vee angle chosen, 45 degrees, left little room for manifold clutter.

He chose a large aluminum crankcase, with five main bearings. The crankshaft was counterweighted and fitted with a vibration dampener at the front. The timing chain also drove the generator. The two cylinder blocks had cast nickel-iron liners, which extended down into the crankcase. Heads were of cast iron. The central camshaft, with roller-type followers, actuated tubular pushrods, which in turn worked short rocker arms. With the new zero-lash valve actuator mechanism, it was all very silent.

The V16 was, in effect, two inline eight-cylinder engines in one, sharing a common crankcase and crankshaft. Each block had a complete fuel system, including carburetor and vacuum tank, and its own exhaust from valve to tailpipe. There was one distributor but two coils, which were recessed into the radiator’s header tank. The engine’s power pulses overlapped to produce smoothness, since they occurred every 45 degrees of rotation. Developed brake horsepower was initially 160; eventually it rose to 185, and torque it had aplenty, 300 pound-feet at idle.

Aesthetically it was a work of art, said to be the first powerplant that was truly styled. Wood and clay models were made of the engine as development progressed, and studied for simplicity and appearance as well as serviceability. They were also useful for the “show and tell” sessions during which the program was sold to management. All wiring and hoses were concealed to the extent possible, hidden behind covers or in raceways. Viewed from outside the engine compartment there was no clutter whatsoever.

The engine, of course, was of little use without a body, of which there were plenty to choose from. There were 54 in the catalog from roadster to town car, all from Fleetwood. Some were built in Fleetwood’s original facility in Pennsylvania, others from the new Detroit plant. Many of them did triple duty, available also as V12 or V8, for nine months later the sixteen had a twelve-cylinder brother, created by removing the two end cylinders on each bank. The wheelbase was a whopping 148 inches; by 1934 it had grown to 154, the longest of any American car. A few chassis were bodied by outside coachbuilders, such as Murphy, but not many.

Historians still puzzle over why Cadillac decided to build a sixteen. The company was well established as a quality builder of V8s, and, aside from Marmon, which was not a serious foe, other American luxury manufacturers, particularly Cadillac’s viable competitors like Packard, Lincoln and Pierce-Arrow, were content with twelves. One motivation seems to have been the desire to build the finest motor car in the world. The company’s own advertising attempted to explain it thus: “The story of the V16’s ascendency is an interesting one. In the first place, this car had its inception in the avowed determination of the General Motors Corporation to produce the world’s finest motor car. And while the creation and development of this super car was entrusted to Cadillac, there was made available for the purpose every facility that General Motors itself possessed. No restriction of any nature was permitted to interfere with, or in any way hinder, the realization of the fundamental purpose - to produce the finest medium of personal transportation on earth.”

This car was auctioned off by RM Auctions in January of 2009 at the Arizona Biltmore Resort & Spa, Phoenix, Arizona.

175bhp, 452 cu. in. overhead valve V16 engine, three-speed manual transmission, suspension via front independent coil springs and rear semi-elliptic leaf springs, live rear axle, four-wheel vacuum-assisted mechanical drum brakes. Wheelbase: 154"

Source: RM Auctions
Photo Credit: Simon Clay

Gallery: Cadillac V-16 Imperial Convertible Sedan