Cadillac V16 engine

With its chief competitor, Packard, already having sold a V12 engine against Cadillac's eight-cylinder cars, work began late in the 1920s under Hemmings to produce a car of real impact. Lawrence Fisher, Cadillac General Manager, leaked to the press that the company would also build a V12, hoping to keep the real engine secret.[3]

The original Cadillac V16 could be said to be two overhead valve Buick Straight-8 engine engines on a common crankshaft and crankcase, because each bank operated entirely independently of the other with no other shared components. It sported a narrow 45° bank angle for use in the new Cadillac chassis Cadillac Series 90 V-16 (which became the Fleetwood).[4] The engine was well engineered, with a counterweighted crankshaft (quite a mathematical challenge at the time), overhead valves,[5] and hydraulic tappets.[5] It also had only two single barrel carburetors,[1][5] one for each bank.[1]

The 452 V16 had a 3 in (76 mm) bore and a 4 in (100 mm) stroke, giving an engine displacement of 452 cubic inches (7.4 L). It was therefore known as the Series 452. Cadillac initially rated the engine at 165 bhp (123 kW).[1] It was capable of powering the heavier models to speeds in excess of 80 mph (130 km/h), and 100 mph (160 km/h) for some of the lighter examples.

In all, 3878 Series 452s were built.[5]

This engine was used in the various V-16 models:

• 1930–1934 Series 452 ("A" through "C")
• 1935 Series 60
• 1936–1937 Series 90

The second generation of V16 used an unusually wide vee-angle of 135°, giving a wide but much lower engine to suit the styling tastes of the late 1930s. The two carburetors, one on each bank, and air cleaners were mounted on top of the engine block in this design. These engines had 'square' proportions; bore and stroke were both 3 ¹⁄₄ in (82.6 mm), giving an overall displacement of 431 cubic inches (7.1 L). Cadillac rated these engines at the same 185 bhp (138 kW) as the previous series. These engines were known as the Series 90, as were the cars that used them. The Series 90 V16 was produced from 1938 through 1940.

This engine was used in the 1938-1940 Series 90.

The 431-cubic-inch displacement 1938-40 Cadillac V16 was one of the last new American auto engine designs prior to World War Two. As such, it incorporated some of the latest thinking. Nine main bearings provided a crankshaft main bearing support between each 135 degree opposing pair of cylinders. The square bore and stroke lowered piston speed and promoted crankshaft rigidity, no small matter for an engine with eight cylinders in line per cylinder bank. The side valve engine design was no handicap for the time because the era's typical top engine speed of 3400-3700 rpm provided little opportunity to exploit the high speed breathing efficiency of overhead valves. Luxury car drivers presumably valued smoothness and silence more than high speed power. Hydraulic valve lifters promoted silent running and an absence of periodic adjustment. Unlike most cars of the era, an external oil filter safeguarded the precision valve lifters. Despite the use of side valves, the engine produced as much power as the prior 45 degree V16, and with much less complexity. The earliest engines produced featured an innovative friction wheel drive to the generator. This was soon replaced by a conventional V belt drive. Cadillac claimed that the 1938, 1939, and 1940 Series 90 Sixteen had the best performance of any production car in the world at the time and would accelerate 10-60 in high gear only in 16 seconds. The definitive engineering report on the 135 degree Cadillac V16 engine is "The Evolution of the Cadillac Sixteen engine," by E.W. Seaholm, in charge of Cadillac engine design. It was published by the industry journal "Automotive Industries," November 27, 1937.

Cadillac also built a V12 engine based on the Series 452 engine for 1930 through 1937. It retained the 45° vee-angle and displaced 368 cu in (6,030 cc) from a 3.125 in (79.4 mm) bore and 4 in (100 mm) stroke. Output was rated at 135 hp (101 kW) with two carburetors. The cars were designed to make a statement, so all engine wiring and plumbing was hidden from view.

The V12 was used in the Fleetwood-bodied V-12 models:

• 1930–1935 Series 370 ("A" through "E")
• 1936–1937 Series 80/85

The Cadillac Sixteen concept utilized an all-aluminium pushrod V16 engine based on the same architecture as GM's then-current small-block V8 developments.[6][7] A production version with a base V8 and the option of the V12 engine was planned, but was never approved for production and was ultimately shelved around 2008.[8]

The only other 16-cylinder automotive engines ever attempted were Bugatti's 1915 U16, Marmon's V16, the BMW Goldfisch V16 and Cizeta-Moroder's V16 (actually 2xV8). BRM fielded a V-16 in supercharged 1.5 liter form in 1954, which was powerful but unreliable. In addition, BRM developed an "H-16" engine (flat 8s stacked one atop another driving a third crank to the transmission) for the 1966 3 liter Formula One season. It was heavy and did not produce the expected amount of power. It was used by Lotus in the Model 43, and by BRM in its own F1 car. BRM abandoned the engine in 1967, replacing it with a V-12. A modern, quad-turbocharged W16 engine was used in the EB 16/4 Veyron built by the new Volkswagen-owned Bugatti in the 2000s. Porsche produced a flat 16 for use in their 917 model

• "Sixteen-Cylinder Motor Latest Auto Wonder" Popular Mechanics, March 1930